Thomas 95, 105, 115 Repair Manual

95/ 105 /

115

REPAIR MANUAL

THOMAS

Publication No. 46847
Date: February, 2001

THOMAS EQUIPMENT LIABILITY WARRANTY

THE WARRANTY IS THE ONLY OBLIGATION OF THOMAS OR A THOMAS DEALER TO THE

PURCHASER OR ANYONE ELSE CONCERNING A PRODUCT, ITS SERVICE, ITS USE OR

PERFORMANCE OR ITS LOSS OF USE OR FAILURE TO PERFORM. NEITHER THOMAS NOR A

THOMAS DEALER HAVE MADE AND NEITHER WILL MAKE ANY OTHER EXPRESSED OR IMPLIED

REPRESENTATION, WARRANTY OR AGREEMENT CONCERNING A PRODUCT. NEITHER THOMAS

NOR A THOMAS DEALER HAVE MADE OR WILL MAKE ANY REPRESENTATION, WARRANTY OR

AGREEMENT CONCERNING A PRODUCTS MERCHANTABILITY OR OTHER QUALITY, ITS

SUITABILITY FOR PURCHASER’S PURPOSE (EVEN IF A PURCHASER HAS INFORMED THOMAS OR A

THOMAS DEALER OF THAT PURPOSE), ITS DURABILITY, PERFORMANCE OR OTHER CONDITION.

EVEN IF THOMAS OR A THOMAS DEALER WAS ADVISE OF THE POSSIBILITY OF SUCH LOSS,
NEITHER THOMAS NOR A THOMAS DEALER WILL BE LIABLE TO PURCHASER OR ANYONE ELSE
FOR ANY INDIRECT, INCIDENTAL CONSEQUENTIAL, PUNITIVE, ECONOMIC, COMMERCIAL, OR
SPECIAL LOSS WHICH IS IN ANY WAY ASSOCIATED WITH A PRODUCT. THIS INCLUDES ANY LOSS OF
USE OR NON-PERFORMANCE OF A PRODUCT, ANY REPLACEMENT RENTAL OR ACQUISITION COST,
ANY LOSS OF REVENUE OR PROFITS, ANY FAILURE TO REALIZE EXPECTED SAVINGS, ANY
INTEREST COSTS, ANY IMPAIRMENT OF OTHER GOODS, ANY INCONVENIENCE OR ANY LIABILITY
OF PURCHASER TO ANY OTHER PERSON.

PURCHASER MAY NOT ATTEMPT TO ENLARGE ITS RIGHTS UNDER THE WARRANTY BY MAKING
A CLAIM FOR INDEMNITY, FOR BREACH OF CONTRACT, FOR BREACH OF COLLATERAL WARRANTY,
FOR A TORT (INCLUDING NEGLIGENCE, MISREPRESENTATION OR STRICT LIABILITY) OR BY
CLAIMING ANY OTHER CAUSE OF ACTION.

THE WARRANTY IS A CONDITION OF SALE OF THE PRODUCT TO PURCHASER AND WILL
THEREFORE APPLY EVEN IF PURCHASER ALLEGES THAT THERE IS A TOTAL FAILURE OF THE
PRODUCT.

N.B. Read and practice your Thomas operating and servicing instructions. Failure to do this may void your warranty.

Publication Number 46847

February 2001

2

FOREWORD

It is important when ordering replacement parts or making a service inquiry to provide both the
model number and serial number of your Thomas loader. The serial number plate is located at the
rear of the machine on the right hand side fuel tank. In the event that the serial number plate is
missing, the model number and serial number are both stamped into the main frame inside the rear
door, next to the hydraulic control valve.

S / N Tag location

S / N Stamp location

C2347

3

SAFETY PRECAUTIONS

Practically all Service work involves the need to drive the
loader. The Owner’s / Operator’s Manual, supplied with
each loader, contains safety precautions relating to
driving, operating and servicing that loader. These
precautions are as applicable to the service technicians as
they are to the operator and should be read, understood
and practiced by all personnel.

Prior to undertaking any maintenance, repair, overhaul,
dismantling or re-assembly operations, whether within the
shop facility or “out in the field”, may have an effect
upon safety, not only upon the mechanic carrying out the
work but also upon bystanders.

PERSONAL CONSIDERATIONS

* CLOTHING

The wrong clothing or carelessness in dress can
cause accidents. Check to see that you are
suitably clothed. Some jobs require special
protective equipment.

* SKIN PROTECTION

Used motor oil may cause skin cancer. Follow
work practices that minimize the amount of skin
exposed and length of time used oil stays on
your skin.

* FOOTPROTECTION

Substantial or protective footwear with
reinforced toecaps will protect the feet from
falling objects. Additional oil-resistant
soles will help to avoid spilling.

* SPECIALCLOTHING

For certain work it may be necessary to wear
flame or acid resistant clothing.

CAUTION

Avoid injury through incorrect handling of

components. Make sure your are capable of lifting

the object. If in doubt, get help.

EQUIPMENT CONSIDERATIONS

* MACHINE GUARDS

Before using any machine, check to ensure that
the machine guards are in position and
serviceable. These guards not only prevent parts
of the body or clothing coming in contact with
the moving parts of the machine but also ward
off objects that might fly off the machine and
cause injury.

* EYE PROTECTION

The smallest eye injury may cause loss of vision.
Injury can be avoided by wearing eye protection
when engaged in chiseling, grinding, welding,
painting and any other task that involves foreign
matter.

* BREATHING PROTECTION

Fumes, dust and paint spray are unpleasant and
harmful. These can be avoided by wearing
respiratory protection.

* HEARING PROTECTION

Loud noise may damage your hearing and the
longer the exposure the greater the risks of
hearing damage. Always wear hearing protection
when working around loud machinery.

* HAND PROTECTION

It is advisable to use a protective cream before
work to prevent irritation and skin
contamination. After work, clean your hands
with soap and water. Solvents such as white
spirits, paraffin, etc. may harm the skin.

* LIFTING APPLIANCES

Always ensure that lifting equipment, such as
chains, slings, lifting brackets, hooks and eyes
are thoroughly checked before use. If in doubt,
select stronger equipment. Never stand under a
suspended load or raised implement.

* COMPRESSED AIR

The pressure from a compressed air line is often
as high as 100 PSI (6.9 Bar). Any misuse may
cause injury.

Never use compressed air to blow dust, filing
dirt, etc. away from your work area unless the
correct type of nozzle is fitted.

Compressed air is not a cleaning agent. It will
only move dust etc. from one place to another.
Look around before using an air hose as
bystanders may get grit into their eyes, ears and
skin.

4

SAFETY PRECAUTIONS

* HAND TOOLS

Many cuts, abrasions and injuries are caused by
defective tools. Never use the wrong tool for the
job as this leads either to some injury or to a
poor job done.

Never Use:

A hammer with a loose or split handle.
Spanners or wrenches with splayed or worn
jaws.
Wrenches or files as hammers; drills or
clevis pins or bolts as punches.

For removing or replacing hardened pins use a
copper or brass drift rather than a hammer.

For dismantling, overhaul and assembly of major
and sub-components always use the Special
Service Tools recommended. These will reduce
the work effort, labor time and the repair cost.

Always keep tools clean and in good working
order.

* ELECTRICITY

Electricity has become so familiar in day to day
usage that it’s potentially dangerous properties
are often overlooked. Misuse of electrical
equipment can endanger life.

Before using any electrical equipment,
particularly portable appliances, make a visual
check to ensure that the cable is not worn or
frayed and that the plugs, sockets etc. are intact.
Make sure you know where the nearest isolating
switch for your equipment is located.

GENERAL CONSIDERATIONS

* HOUSEKEEPING

Many injuries result from tripping or slipping
over, or on, objects or materials left lying around
by a careless worker.

Prevent these accidents from occurring. If you
notice a hazard, don’t ignore it, remove it.

A clean, hazard free place of work improves the
surroundings and daily environment for
everybody.

* FIRE

Fire has no respect for persons or property. The
destruction that a fire can cause is not always
fully realized. Everyone must be constantly on
guard.

- Extinguish matches, cigars, cigarettes etc.
before throwing them away.

- Work cleanly, disposing of waste material into
proper containers.

- Locate all the fire extinguishers and ensure all
personnel know how to operate them.

- Do not panic, warn those near and sound the
alarm.

- Do not allow or use an open flame near the
loader fuel tank, battery or component parts.

* FIRST AID

In the type of work that mechanics are engaged
in, things such as dirt, grease, fine dust etc. all
settle upon the skin and clothing. If a cut,
abrasion or burn is disregarded it may be found
that a septic condition has formed in a short time.
What appears at first to be trivial could become
painful and injurious. It only takes a few minutes
to have a fresh cut dressed but it will take longer
if you neglect it.

* SOLVENTS

Use only cleaning fluids and solvents that are
known to be safe. Certain types of fluids can
cause damage to components such as seals, etc.
and can cause skin irritation. Solvents should be
checked that they are suitable not only for the
cleaning of components and individual parts but
also that they do not affect the personal safety of
the user.

* CLEANLINESS

Cleanliness of the loader hydraulic system is
essential for optimum performance. When
carrying out service and repairs, plug all hose
ends and components connections to prevent dirt
entry.

Clean the exterior of all components before
carrying out any form of repair. Dirt and abrasive
dust can reduce the efficiency and working life
of a component and lead to costly replacement.
Use of a high pressure washer or steam cleaner is
recommended.

5

SAFETY PRECAUTIONS

OPERATIONAL CONSIDERATIONS

* Stop the engine, if at all possible, before

performing any service.

* Place a warning sign on loaders which, due to

service or overhaul, would be dangerous to start.
Disconnect the battery leads if leaving such a
unit unattended.

* Do not attempt to start the engine while standing

beside the loader or attempt to bypass the safety
starting system.

* Avoid prolonged running of the engine in a

closed building or in an area with inadequate
ventilation as exhaust fumes are highly toxic.

* Always turn the radiator cap to the first stop to

allow pressure in the system to dissipate when
the coolant is hot.

* Never work beneath a loader which is on soft

ground. Always take the unit to an area which
has a hard working surface, preferably concrete.

* If it is found necessary to raise the loader for

ease of maintenance, make sure that safe and
stable supports are installed beneath the main
frame before commencing work.

* Use footsteps or working platforms when

servicing those areas of the loader that are not
within easy reach.

* Before loosening any hoses or tubes, switch off

the engine, remove all pressure in the lines by
operating the foot pedals several times. This will
remove the danger of personal injury by oil
pressure.

* If high lift attachments are installed on a loader,

beware of overhead power and telephone lines
when travelling. Drop attachment near to ground
level to increase stability and minimize risks.

* Do not park or attempt to service a loader on an

incline. If unavoidable, take extra care and block
the wheels.

* Escaping hydraulic / diesel fluid under pressure

can penetrate the skin causing serious injury. Do
not use your hand to check for leaks. Use a piece
of cardboard or paper to search for leaks. Stop
the engine and relieve pressure before connecting
or disconnecting lines. Tighten all connections
before starting the engine or pressurizing the
lines. If any fluid is injected into the skin, obtain
medical attention immediately.

* Prior to removing wheels and tires from a loader,

check to determine whether additional ballast
(liquid or weight) has been added. Seek
assistance and use suitable equipment to support
the weight of the wheel assembly.

* When inflating tires beware of over inflation.;

constantly check the pressure. Over inflation can
cause tires to burst and result in personal injury.

* Safety precautions are very seldom the figment

of someone’s imagination. They are the result of
sad experience where most likely someone has
paid dearly through personal injury.

* Heed these precautions and you will protect

yourself accordingly. Disregard them and you
will duplicate the sad experiences of others.

* Prior to pressure testing, make sure all the hoses

and connectors on both the loader and on the test
machine are in good condition and tightly sealed.
Pressure readings must be taken with the gauges
specified. The correct procedure should be
rigidly observed to prevent damage to the system
or the equipment and to eliminate the possibility
of personal injury.

* Always lower equipment to the ground when

leaving the loader.

6

SAFETY PRECAUTIONS

SERVICE TECHNIQUES

A. SERVICE SAFETY

Appropriate service methods and proper repair
procedures are essential for the safe, reliable
operation of all motor vehicles as well as the
personal safety of the individual doing the work. This
shop manual provides general directions for
accomplishing service and repair work with
tested effective techniques. Following them will help
assure reliability.There are numerous variations in
procedures, techniques, tools and parts for servicing
vehicles as well as in the skill of the individual doing the
work. This manual cannot possibly anticipate all such
variations and provide advice or cautions as to each.
Accordingly, anyone who departs from the instructions
provided in this manual must first establish that he or she
compromises neither his personal safety nor the vehicle
integrity by his choice of methods, tools or parts.

B. SERVICE TECHNIQUES

Clean the exterior of all components before carrying out
any form of repair. Dirt and abrasive dust can reduce the
efficient working life of a component and lead to costly
replacement.

Use cleaning fluids which are known to be safe. Certain
types of fluid can cause damage to O rings and cause skin
irritation. Solvents should be checked that they are
suitable for the cleaning of components and also that they
do not risk the personal safety of the user.

Time spent on the preparation and cleanliness of working
surfaces will pay dividends in making the job easier and
safer and will result in overhaul components being more
reliable and efficient in operation.

When installing a new hose, loosely connect each end and
make sure the hose takes up the designed position before
tightening the connection. Clamps should be tightened
sufficiently to hold the hose without crushing and to
prevent chafing.

The hoses are the arteries of the unit; be sure they are in
good condition when carrying out repairs or maintenance
otherwise the machines output and productivity will be
affected.
After hose replacement to a moving component, check
that the hose does not foul by moving the component
through the complete range of travel.

Hose connections which are damaged, dented , crushed or
leaking, restrict oil flow and the productivity of the
components being served. Connectors which show signs
of movement from the original swaged position have
failed and will ultimately separate completely.

A hose with a chafed outer cover will allow water entry.
Concealed corrosion of the wire reinforcement will
subsequently occur along the hose length with resultant
hose failure.

Ballooning of the hose indicates an internal leakage due
to structural failure. This condition rapidly deteriorates
and total hose failure soon occurs.

Kinked, crushed, stretched or deformed hoses generally
suffer internal structural damage which results in oil
restriction, a reduction in the speed of operation and
ultimate hose failure.

Free moving, unsupported hoses must never be allowed to
touch each other or related working surfaces. This causes
chafing which reduces hose life.

Replace O rings, seals or gaskets whenever they are
disturbed. Never mix new and old seals and O rings,
regardless of condition. Always lubricate new seals and O
rings with hydraulic oil before installation.

When replacing component parts use the correct tool for
the job.

C. HOSES AND TUBES

Always replace hoses and tubes if the end connections are
damaged. Be sure any hose installed is not kinked or
twisted.

D. PRESSURE TESTING

Prior to pressure testing, be sure all hoses are in good
condition and all connections tight. Pressure readings
must be taken with gauges of specified pressure readings.

The correct procedure should be rigidly observed to
prevent damage to the system or the equipment and to
eliminate the possibility of personal injury.

7

SAFETY PRECAUTIONS

E. BEARINGS

Bearings which are considered suitable for further service
should be cleaned in a suitable solvent and immersed in
clean lubricating oil until required.

Installation of a bearing can be classified into two (2)
ways:

press fit on rotating parts such as shafts and gears,
push fit into static locations such as reduction gear

houses.
Where possible, always install the bearing onto the
rotating components first. Use the correct tools or a press
to install a bearing or bushing. In the absence of the
correct tools or press, heat the bearing and / or casing in
hot oil to assist the installation of the bearing.

When bearings or bushings are removed, always carefully
check that the bearing is free from discoloration and signs
of overheating. Also check for mechanical damage such
as excessive clearance, nicks and scuffing. If in doubt,
replace the bearings or bushings.

C729

Bearings should never be removed unless absolutely
necessary. Always use the recommended puller to reduce
the risk of bearing or related component failure.

These bearings and bushings are subjected, in normal
operation, to high working loads and adverse conditions.

Be sure during normal routine servicing, maintenance or
repair that bearings are given the right attention and are
installed with care.

F. BOOM SUPPORTS
For safety while performing regular service or
maintenance work, the loader is equipped with boom
supports.

The boom supports, when extended, prevent the boom
arms from dropping if hydraulic pressure is relieved or
the foot control pedals are accidentally cycled.

To operate the boom supports, first remove any bucket or
attachment from the quick - tach; raise the boom arms to
full height and shut off the engine. Raise the boom
handles up and push out toward the boom arms to extend
the boom supports. (fig. C729, C321)

WARNING

To avoid personal injury, service the loader with the
boom arms down and the bucket or attachment
lowered to the ground. If it is necessary to service the
loader with the boom arms raised, be sure to engage
the boom supports. Never work under or around a
loader with raised boom arms without the boom
supports engaged.

8

THOMAS

9

TABLE OF CONTENTS

Section 1 Hydraulic System

Hydraulic Circuit...............................................................................1.1

Gear Pump .........................................................................................1.2

Control Valve.....................................................................................1.3

Hydraulic Cylinders...........................................................................1.4

Oil Filter .............................................................................................1.5

Oil Cooler..........................................................................................1.6

Oil Reservoir......................................................................................1.7

Trouble Shooting ...............................................................................1.8

Torque Chart ......................................................................................1.9

Section 2 Hydrostatic Drive System

Hydrostatic Drive Circuit..................................................................2.1

Specifications.....................................................................................2.2

General Information...........................................................................2.3

Trouble Shooting ...............................................................................2.4

Pressure Tests.....................................................................................2.5

Towing Procedure ..............................................................................2.6

Flushing The Hydraulic System ........................................................2.7

Start - up Procedure ...........................................................................2.8

Gear Pump Replacement...................................................................2.9

Tandem Pump Replacement ..............................................................2.10

Tandem Pump Parts Diagram............................................................2.11

Drive Motor .......................................................................................2.12

Section 3 Final Drive

Specifications and Maintenance ........................................................3.1

Lubrication .........................................................................................3.2

Drive Chain........................................................................................3.3

Drive Motor Sprocket........................................................................3.4

Axle Assembly...................................................................................3.5

Trouble Shooting ...............................................................................3.6

Section 4 Controls

Steering..............................................................................................4.1

Foot Pedals.........................................................................................4.2

Hand Controls ....................................................................................4.3

Throttle...............................................................................................4.4

Restraint Bar......................................................................................4.5

Parking Brake ....................................................................................4.6

Trouble Shooting ...............................................................................4.7

10

TABLE OF CONTENTS

Section 5 Electrical

General Information...........................................................................5.1

Wiring Schematics.............................................................................5.2

Instrumentation..................................................................................5.3

Ignition Switch...................................................................................5.4

Engine Glow Plugs ............................................................................5.5

Battery................................................................................................5.6

Electrical Panel..................................................................................5.7

Starter Circuit.....................................................................................5.8

Charging Circuit ................................................................................5.9

Safety Circuit .....................................................................................5.10

Cooling Fan Circuit ..........................................................................5.11

Auxiliary Circuit ................................................................................5.12

Accessory Circuit...............................................................................5.13

Trouble Shooting ...............................................................................5.14

Section 6 Main Frame

Quick - Tach .......................................................................................6.1

Boom Arms........................................................................................6.2

Boom Support....................................................................................6.3

ROPS .................................................................................................6.4

Rear Door...........................................................................................6.5

Section 7 Engine

Maintenance .......................................................................................7.1

Cylinder Head ....................................................................................7.2

Replacement.......................................................................................7.3

Specifications.....................................................................................7.4

Trouble Shooting ...............................................................................7.5

Section 8 Maintenance & Specifications

Maintenance .......................................................................................8.1

Trouble Shooting ...............................................................................8.2

Special Tools ......................................................................................8.3

Specifications.....................................................................................8.4

Conversion Charts..............................................................................8.5

11

THOMAS

12

SECTION 1 HYDRAULIC SYSTEM

1

Hydraulic Circuit 1.1

Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-2

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-3

Maintenance Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-3

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-4 ~ 5

Gear Pump 1.2

Replacing the Gear Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-6

Start - up Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-7

Testing (See control valve relief) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-14 ~ 15

Control Valve 1.3

Testing / Adjusting the Relief Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-8

Control Valve Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-9

Control Valve Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .pg. 1-10

Exploded Illustration (to S / N LC001080) . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-12 ~ 13

Exploded Illustration (S / N LC001081 onward) . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-15

Control Valve Disassembly / Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-16 ~ 25

Hydraulic Cylinders 1.4

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-26

Testing Piston Seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-27

Lift Cylinder Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-28

Tilt Cylinder Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-29

Cylinder Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-30 ~ 31

Cylinder Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-32

Cylinder Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-32 ~ 33

Hydraulic Oil Filter 1.5

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-34

Filter Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-34

Hydraulic Oil Cooler 1.6

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-35

Oil Cooler Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-35

Hydraulic Oil Reservoir 1.7

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-36

Checking the Oil Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-36

Adding Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-36

Servicing the Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-37

Trouble Shooting 1.8

Trouble Shooting Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-38 ~ 39

Torque Chart 1.9

Hydraulic Hose and Fitting Torque Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 1-39

1-1

HYDRAULIC CIRCUIT 1.1

Lift Cylinders Tilt CylindersAuxiliary Couplers

C1008

NOTE: Foot pedal control operated machine illustrated. Hydraulic fluid comes out the port closest to the spool

1-2

Control Valve Outlet

end of the valve when the spool is pushed in.
Hydraulic fluid received at the fixed end of the cylinder
pushes it out. When the hydraulic cylinder receives fluid
at the ram (rod) end, it retracts.

SPECIFICATIONS & MAINTENANCE 1.1

1

Hydraulic Specifications

Pump Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gear, 0.61 cu. in. (11cc)

Pump Brand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sauer Sundstrand

Pump Capacity (theoretical) . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 GPM (33 LPM)

Rated Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3000 RPM

Control Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Parallel Type

Main Relief Pressure, +/- 50PSI (3.5 Bar) . . 2150 PSI (148 Bar) @ Zero Flow

Reservoir Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 L (9 gallons)

Fluid Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10W30 API SE / CD Oil

Reservoir Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Micron

System Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Micron

Lift Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (2) 2’’ Bore Diameter

Lift Cylinder Rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.125’’ Diameter

Tilt Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (2) 2’’ Bore Diameter

Tilt Cylinder Rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.125’’ Diameter

Lift Cycle + / - 1.5 seconds (Up / Down) . . . . . . . . . . . . . . . . . . . . . . 5.4 / 3.54

Tilt Cycle + / - 1.5 seconds (Up / Down) . . . . . . . . . . . . . . . . . . . . . 2.35 / 3.06

Allowable Drop, Measured at the Cylinder Rod, Engine Off,

@ Rated Capacity and Operating Temperature . . . . . . 1.5’’ (38mm) / 3 Minutes

Maintenance Schedule . . . . . . . . . First (HRS) . . . . Every (HRS)

Oil level check . . . . . . . . . . . . . . . . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . 8

Oil filter change . . . . . . . . . . . . . . . . . . . . . . . . 50 . . . . . . . . . . . . . . . . . 150

General system check (leaks etc.) . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . 8

Lubricate (grease pivots) . . . . . . . . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . 8

Reservoir filter change . . . . . . . . . . . . . . . . . 1000 . . . . . . . . . . . . . . . 1000

Hydraulic oil change . . . . . . . . . . . . . . . . . . . 1000 . . . . . . . . . . . . . . . 1000

1-3

GENERAL INFORMATION 1.1

Hydraulic System

Oil is drawn from the hydraulic oil reservoir through a
100 micron element. From there it travels to the main
hydraulic pump. (fig. C2353).

The hydraulic pump is a gear type which is driven by a
shaft and coupler through the hydrostatic drive pump at
engine speed. The oil then flows from the gear pump to
the hydraulic control valve. (fig. C2347).

Gear pump location

The hydraulic control valve is equipped with an
adjustable relief valve which is adjusted to 2150 PSI (148
Bar). The control valve is a parallel type with 3 spools
(banks). The various spools activate the boom, bucket and
auxiliary hydraulic functions.

When the spools are in neutral, oil flows from the
hydraulic gear pump, through the control valve and
returns to the 10 micron hydraulic filter. From the
hydraulic filter, the fluid flows to charge the tandem
hydrostatic pump and pressurize the hydraulic brake
release system and then back to the hydraulic reservoir.
Each control valve section spool end contains a centering
spring which returns the spool to neutral when the foot
pedal, or control handle, is released. (fig. C2350).

The boom section, on foot control operated loaders, has a
detent mechanism to hold the spool in the float position.
The auxiliary section is operated by foot pedal operation,
or may have an optional electrical solenoid operated
control, and may be engaged momentarily by the control
lever mounted switch, forward or reverse, or by engaging
the dash mounted toggle switch for constant power in the
forward direction only.

C2353

Control valve location

C2347

Spring return

The system relief valve operates whenever a hydraulic
function has been restricted or over loaded. (fig. C2248).
To protect against excessive pressure build up, the relief
valve opens and allows oil to return to the return outlet.
The system relief valve is adjustable, and is preset at
2150 PSI. (148 Bar)

1-4

C2350

Relief valve

C2348

GENERAL INFORMATION 1.1

1

THOMAS

1-5

GEAR PUMP 1.2

Replacement

Start the gear pump removal procedure by removing any
attachment, raising the boom arms and engaging the
boom support pins. Shut off the engine.

WARNING

To prevent personal injury, never work under the
boom arms without the boom supports engaged.

1 Remove the seat and hydrostatic shield. (fig. C2358,
C2360)
2 Attach a vacuum system to the hydraulic oil reservoir
filler location. Or drain the oil reservoir. Seal the threads
on the drain plug, if removed, with teflon tape or a liquid
form of pipe sealant before installing.
3 Disconnect the hydraulic hoses from the gear pump.
(fig. C2353) Remove the pump fittings. Cap all open
hoses to prevent contamination. After capping ends you
may unhook vacuum system from oil reservoir.
4 Remove the 2 bolts holding the gear pump to the
hydrostatic tandem section. (fig. C2353) Remove the gear
pump. Check the seal. Replace if required.

Hydrostatic shield

C2358

Gear pump

IMPORTANT

If gear pump replacement is being done because of
failure, the hydraulic system and oil should be
checked for contamination. See section 2.7.

5 Replace gear pump in reverse order.
6 Start the engine and check for leaks. Do not use your
hands to find leaks.
7 Check the fluid level in the hydraulic oil reservoir
and replenish as required. (fig. C2354)
8 Follow the Start Up Procedure upon completing
repairs. See next page.

WARNING

Use caution when dealing with fluid under pressure.
Escaping fluid under pressure can penetrate the skin
and cause serious injury.

IMPORTANT

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs on
all open lines and ports. Follow the torque chart
when tightening lines and fittings.

C2360

Screws

Hyd. lines

C2353

Oil level

1-6

C2354

GEAR PUMP 1.2

1

Start up Procedure

1 Mount the gear pump to the loader. (fig. C2353)

2 Connect the hydraulic lines. Torque fittings and lines
according to the torque chart section 1.8.

3 Start the pump and run for 3 minutes each @

a. Half speed at zero flow
b. Half speed, intermittently loaded to 500 psi (35

bar)

c. Full speed, intermittently loaded to 1000 psi (69

bar)

4 Check for leaks.

5 Check flow and pressure at rated speed as outlined in
section 1.3.

WARNING

Use caution when dealing with fluid under
pressure. Escaping fluid under pressure can
penetrate the skin and cause serious injury. Never
use your hands to check for system leaks.

Screws

Hyd. lines

C2353

Intermittently load the gear pump at start up

IMPORTANT

Be sure the hydraulic oil reservoir is at the proper
level before performing test.

Flow test meter p / n 960456

C2352

1-7

CONTROL VALVE 1.3

Testing and Adjusting the Relief Valve Pressure

NOTE: This test also checks the status of the gear

pump capacities.

Hoses and gauges required for this test must be capable
of withstanding 3000 PSI (207 Bar) continuous pressure,
and hydraulic flow meter capable of measuring 30 gallons
per minute. (113 LPM)

1 The female coupler attached to the loader provides
the power out when the auxiliary control is engaged. (fig.
C2351) Connect the flow meter and pressure gauge inlet
side to match the power out of the female auxiliary
coupler to prevent meter and gauge damage. Be sure to
connect a return line to the male auxiliary hydraulic quick
coupler. Install the flow meter / pressure tester to the
auxiliary hydraulic quick couplers. (fig. C2352)
2 Start the engine and engage the auxiliary hydraulic
system. Increase the engine speed to full operating RPM.
(See Section 7 for checking and adjusting engine speed to
3000 RPM plus or minus 25 RPM)
3 Turn the flow control valve on the flow meter to
restrict the oil flow down to 2 GPM. (7.5 LPM) As you
are turning the flow control valve, watch the pressure
gauge and make sure it does not go over 3000 PSI.(207
Bar) Stop further adjustment immediately if the reading
goes over this setting. Shut off the auxiliary hydraulic
system and shut off the engine. Move to step 6 to make
initial setting.
4 Repeat steps 2 and 3 if necessary. Allow the loader to
operate at this setting until the oil temperature has
increased to 160° F (71ºC), operating temperature.
5 Turn the flow control valve further to restrict the oil
flow to no flow. (Zero) Correct pressure setting is 2150
PSI +/- 100 PSI. (148 Bar, +/-6.9 Bar)
6 If adjustment is necessary, shut down the auxiliary
hydraulic system, shut off the engine and return the flow
control valve to the open position. Locate the control
valve in the engine compartment.
7 Loosen the jam nut on the relief valve adjusting
screw and turn the screw clockwise, counting the turns,
until the screw bottoms out. (fig. C2348)
8 Turn the screw back out lesser turns than you turned
in to increase pressure, or out more turns to decrease
pressure.
9 Retake the pressure readings by performing steps 2
through 5. If necessary make further adjustments by
repeating steps 6 through 9.

NOTE: If inadequate pressure and / or flow is not
available, the gear pump could be failing or the inlet
to the gear pump is restricted.

Auxiliary couplers

Pressure out

C2351

C2352

CAUTION

Adjusting the relief valve setting too high may cause
damage to the gear pump.

WARNING

To prevent personal injury or damage to the loader,
do not adjust the relief valve while the engine is
operating.

Relief valve

Jam nut

C2348

1-8

CONTROL VALVE 1.3

1

Control Valve Removal

1 Remove any attachment, lower the boom arms,
engage the parking brake and shut off the engine

IMPORTANT

Clean the work area prior to repair. Cap all open

lines, fittings and ports to prevent contamination.

C2348

Solenoid coil
mounting nuts

2 Disconnect the spool locks solenoid, and electrical
auxiliary solenoid wiring connectors if equipped. (fig.
C2348, C2349)

3 Disconnect the control cables. (fig. C2367)

4 Disconnect the return line from the control valve and
remove the adapter fitting. Plug and cap all open ports
and hose ends.

5 Disconnect the 6 hoses going to the boom, bucket
and auxiliary circuits. Marking the hoses as you remove
them is recommended for safety and to ease re-assembly
and assure the circuits are functioning properly at restart.

6 Disconnect the the inlet hose coming from the gear
pump. Cap the hose and fitting and remove the adapter
fitting in the control valve.

Solenoid coil

Return
line

C2349

Disconnect control cables

C2367

7 Remove the 4 bolts holding the control valve to the
mount and remove the control valve. (fig. C2350)

Control valve mounts

C2350

1-9

CONTROL VALVE 1.3

Control Valve Installation

When installing a new control valve, always inspect the
exterior for shipping or other damage, such as bent
brackets, broken spring return caps or damaged spool
lock mechanism. Repair all damaged parts before
installation to the loader.

1 Mount the control valve to the loader. (fig. C2324a)

IMPORTANT

Follow the hydraulic fitting torque chart in Section

1.10 when connecting fittings and lines.

2 Connect the control cables to the spools.

3 Connect the various hydraulic lines to their proper
ports. (fig. C2324b).

Install valve to mount

C2324a

Control valve fittings

WARNING

Use extreme caution when checking the hydraulic
system for leaks. Fluid under pressure can penetrate
the skin and cause serious injury.

4 Connect the solenoid coils to the control valve locks.
Apply a drop of Loctite 242 (blue) to the knurled
retaining nut.

WARNING

All safety switches must be connected and
functioning to prevent possible operator injury.

5 Verify fluid level in th hydraulic oil reservoir. (fig.
C2354). Top off as required to bring oil level to
approximately half way in the site gauge.

WARNING

Verify the relief valve pressure setting after replacing
or servicing the control valve.

C2423b

Check fluid level

C2354

Replenish fluid as required

1-10

C2355

1

THOMAS

1-11

CONTROL VALVE 1.3

35

9

30

29

1

34

33

32

31

2

36

7

3

4

5

6

7

Salami Model to S / N LC001080

8

9

23

6

10

11

28

27

26

22

4

25

20

7

21

24

12

13

12

14

15

16

17

18

19

C1079

1-12

CONTROL VALVE 1.3a

1

Diagram C1079 Legend

1 Auxiliary spool spring return
2 Tilt spool spring return
3 Lift spool spring return
4 Plate
5 Washer
6 Seal shim
7 Seal
8 Outlet / lift section body
9 Mounting bracket
10 Section seals
11 Knurled nut
12 Seal
13 Solenoid coil
14 Spool lock solenoid post
15 Spring
16 Lock pin
17 Electrical connector
18 Screw
19 Spool lock body
20 Lock washer
21 Screw
22 Scraper seal
23 Seal
24 Lift spool
25 Tilt spool
26 Auxiliary spool
27 Relief valve body
28 Washer seal
29 Spring washer
30 Spring
31 Poppet valve
32 Inlet / auxiliary section body
33 Tie bolt
34 Flat washer
35 Nut
36 Tilt section body

1-13

CONTROL VALVE 1.3

Disassembly / Repair

Remove the hydraulic control valve as outlined in the
removal section, page 1-7. Ensure all openings are
plugged to prevent solvents and dirt from contaminating
the control valve assembly. Before disassembling the
hydraulic control valve, clean the body with a suitable
solvent and dry with compressed air.

WARNING

To avoid eye injury, use safety goggles when clean ­ing with compressed air.

Refer to diagram C1079, pg. 1-11, to assist in the
disassembly of the control valve.

1 Remove the solenoid coils and O-ring seals. (fig.
C2368).

2 Remove the locking pin assembly from the adapter
block. (fig. C2369)

3 Remove the pressure relief valve. (fig. C2370) Tip
the valve down slightly to ensure the valve poppet comes
out with the spring.

O-ring seals

C2368

Locking pin assembly

C2369

Note: Figure C2371 shows an exploded view of the
relief valve system.

Relief valve assembly

C2370

Sealing washer

Cap

C2371

Spring

Valve poppet

Spring washer

1-14

CONTROL VALVE 1.3

1

Disassembly / Repair (cont’d)

4 Remove the screws retaining the lock adapters to the
control valve assembly. (fig. C2372).

5 Remove the plate and adapter from the control valve
and spool. (fig. C2373, C2374)

Remove screws

C2372

Scraper seal plate

6 Remove the O-ring seals and seal shim. (fig. C2374).
Discard the seals and replace with new.

7 Clean the lock adapter with solvent and inspect the
inside of the lock adapter for excessive wear such as
gouging or chipping. Replace with new if worn.

8 Lubricate a new spool O-ring with system oil and
install to the lock adapter. (fig. C2375)

C2373

C2374

Spool O-ring

Section O-ring

O-ring shim

Spool O-ring

C2375

1-15

CONTROL VALVE 1.3

Disassembly / Repair (cont’d)

9 Lubricate the spool O-ring shim with system oil and
install over spool seal. (fig. C2376).

10 Lubricate the section O-ring seal with system oil and
install to the lock adapter assembly. (fig. C2377).

Spool O-ring shim

C2376

Section O-ring seal

11 Figure C2378 shows the completely resealed lock
adapter assembly ready to be installed to the control valve
assembly.

12 Remove the screws retaining the spring return caps to
the control valve assembly. (fig. C2379). Remove the
spring return assemblies.

C2377

Lock adapter assembly

C2378

Remove screws

1-16

C2379

CONTROL VALVE 1.3

1

Disassembly Repair (cont’d)

13 Note: The plastic cap over the tilt spring has flat
washers to distribute the load of the mounting screws to
prevent cap damage. (fig. C2380). Be sure to install the
flat washers when reassembling to the control valve.

14 Figure C2381 shows spring assemblies and detent
mechanisms as viewed with the caps removed.

Tilt spring return cap

Mounting screws

Flat washers

C2380

Return springs

15 Remove the section spools noting their location to
the appropriate bores. (fig. C2382). Do not replace the
spools in any other spool bores than the one it came out
of. Clean the spools and valve sections with solvent and
inspect for gouging or chipping. Replace sections as
required. Minor scratches on the spool may be removed
with fine emery cloth. Be sure to remove all solvent from
the control valve body if no further disassembling of the
control valve is to be performed.

16 Install new O-ring seals at time of assembly. (fig.
C2383) Lubricate the seal, bore and spool with system oil
when reassembling the components.

C2381

Remove spools

C2382

Spool O-ring

C2383

1-17

CONTROL VALVE 1.3

Disassembly / Repair (cont’d)

17 Install the O-ring spacer shim to the spool O-ring
seal. (fig. C2384).

18 Install the flat washer over the O-ring spacer. (fig.
C2385) The spring return side of the control valve is now
complete.

C2384

19 The auxiliary section, section without lock adapter,
has an O-ring seal located in a machined groove in the
section housing. (fig. C2386) Remove the seal using a
pick tool and replace with new. Lubricate the O-ring with
system oil. Figure C2387 shows the seal installed.

C2385

C2386

1-18

Seal

C2387

CONTROL VALVE 1.3

1

Disassembly / Repair (cont’d)

20 Section seals may be replaced without removing
spools and spring return mechanisms. Loosen the bolts
retaining the control valve sections together. (fig. C2388).
Upon assembly follow the torque specifications given
Section 8.

Loosen section bolts

C2388

21 Note the flat spacer washers used on the upper bolts.
(fig. C2389)

22 Remove the bolts and mounting brackets. (fig.
C2390)

Flat spacer washer

C2389

Mounting bracket

23 Separate the control valve sections. (fig. C2391)

C2390

Separate sections

C2391

1-19

CONTROL VALVE 1.3

Disassembly / Repair (cont’d)

24 Remove and discard the O-ring seals between the
sections. Replace with new. Be sure to replace the O-ring
seal spacer shim upon assembly. (fig. C2392, C2393).
Lubricate the seals with system oil upon assembly. When
reassembling the control valve sections, follow the torque
specifications in Section 8.

O-ring seals

Spacer shim

C2392

O-ring seals

Spacer shim

25 To remove the detent mechanism and spring from the
spool, place an allen wrench or screwdriver blade through
the spool eyelet to hold the spool from turning while
removing the spring and detent mechanism. (fig. C2394).

26 Remove the mechanism and arrange the parts in
order of placement. (fig. C2395) Inspect the detent part
and bushings for burrs and wear. Replace if worn.

C2393

Removing spring assembly

C2394

Exploded view of spring and
detent assembly

Spool bores

1-20

C2395

CONTROL VALVE 1.3

1

Disassembly / Repair (cont’d)

27 Replace the spring and detent mechanism in the
reverse order. (fig. C2396). Install spring bushing.
Lubricate the spring bushings with Castrol Spheerol
grease or equivalent.

28 Install sleeve bushing. (fig. C2397). Lubricate the
bushing with Castrol Spheerol grease or equivalent.

Spring bushing

C2396

29 Install the spring, spring bushing and detent. (fig.
C2398) Install the bolt. Apply Loctite 242 (blue) to the
threads and tighten to specifications given in Section 8.

30 To service the spring return mechanism in the cover,
remove the circlip retaining the cover. (fig. C2404).

Sleeve bushing

C2397

Spring

Detent

Spring bushing

Bolt

C2398

Remove circlip

C2404

1-21

CONTROL VALVE 1.3

Disassembly / Repair (cont’d)

31 Remove the cover. (fig. C2405).

32 Remove the spring washer. (fig. C2406).

Remove cover

C2405

Remove washer

33 Remove the spring. (fig. C2407). Inspect the spring
for broken or sacked coils. Replace the detent spring
return with a new kit if spring damage is apparent.

34 Remove the detent ball sleeve and cup. (fig. C2408).

C2406

Remove spring

C2407

Remove sleeve
and cup.

1-22

C2408

1

CONTROL VALVE 1.3

Disassembly / Repair (cont’d)

35 Separate the sleeve and cup assembly. (fig. C2409).
Inspect the tapered cup, balls and sleeve for wear.
Replace with new detent kit assembly if wear is evident.

36 Remove the spring washer. (fig. C2410).

37 Clean all parts with solvent. Lubricate all parts with
Castrol Spheerol grease or equivalent.

Inspect cup, sleeve and balls

C2409

Remove washer

C2410

38 Replace the greased detent balls to the cup and sleeve
(fig. C2411) and reassemble the complete spring return
mechanism in the reverse order above.

39 The grease holds the detent balls in position during
assembly to the control valve and spool. (fig. C2412)
40 Replace the cap assembly to the control valve and
tighten the screws evenly.

IMPORTANT

Check to make sure the detent balls are in position
before assembling to the control valve to assure
proper function of the control spool and detent
mechanism.

Grease detent and balls

C2411

Detent balls in
position

C2412

1-23

THOMAS

1-24

1

CONTROL VALVE 1.3

Screw

Screw

Bushing

Spring

Bushing

Screw

Cap

Cap

Block

Detent

Spring

Screw

Washer

Cap

Spring

Bushing

Bushing

Ball Holder

Block

Detent

Walvoil Model, S / N LC0001081 onward

Spring

Check Valve

Anti-cav

Main Body

Relief Valve

O-ring

Tilt
Spool

O-ring

Seal Washer

Lift Spool

Lock Pin

Scraper

Seal

Nut

O-ring

Coil

O-ring

Post

Spring

Lock Block

Screw

Cover

Scraper Seal

Aux. Spool

Cover

C2776

1-25

CONTROL VALVE 1.3

Disassembly / Repair

Before disassembling the hydraulic control valve, clean
the body with a suitable solvent and dry with compressed
air.

To avoid eye injury, use

WARNING

Ensure all openings are plugged to prevent solvents and
dirt from contaminating the control valve assembly. Refer
to diagram C2776, pg. 1-25, to assist in the disassembly
of the control valve.

1 Remove the pressure relief valve. Discard the O­rings (fig. C2975).

safety goggles when clean­ing with compressed air.

Removing the relief valve

O-ring seal

C2975

Removing the solenoid coils from the spool locks

O-ring seal

2 Remove the solenoid coils and locking pin from the
valve lock block. (fig. C2235, C2236) There are 2 O-ring
seals located on either side of the solenoid coils.

3 Remove the outer wiper seal cover from the lock
block. (fig. C2244)

C2235

Removing the lock from the valve

Spring

Lock pin

C2236

Wiper seal cover

1-26

Wiper seal

C2244

CONTROL VALVE 1.3

1

Disassembly / Repair (cont’d)

4 Remove the lock block from the valve. (fig. C2241)

C2241

5 Remove the spring return / centering cap from the
end of the spool. (fig. C2237)

6 Pull out the spool. (fig. C2240) As you pull out the
spool, note it’s smooth action as it comes out of the valve
body. The spool should move freely and smoothly in the
bore of the valve body. Check the control valve spool and
bore for scuff marks or abnormal wear. Replace the spool
and or control valve if signs of wear are present.

Remove the spring centering / return assembly

C2237

Removing the spools from the valve

Seal washer

O-ring seal

7 Remove the check valves from control valve body.
(fig. C2239) They are located between the ports of each
section. Check the seat and poppet of the valve body and
check valve. Replace the check valve and or the control
valve if any signs of wear are present.

C2240

Remove the check valves

Inspect tapered seats

C2239

1-27

CONTROL VALVE 1.3

Disassembly Repair (cont’d)

8 When replacing the spool to the control valve, use
new O-ring seals and apply system oil to the O-rings and
spools. (fig. C2251).

9 Fit the seal washer to the control valve with the
beveled side of the washer facing the control valve. (fig.
C2252) Fit the spool to the control valve now if repairs
are not needed to the detent or spring return mechanism.
Use system oil to lubricate the spool before inserting to
the control valve.

10 Photographs C2238, C2242 are exploded views of
the lift spool detent mechanism. Place the cable end of
the spool in a vice, or insert a screw driver through the
clevis pin holes, to keep it from turning. The detent is
threaded to the spool and can be removed for inspection
or repairs.
Replace broken springs, worn detents and / or damaged
detent balls with a new detent kit.
Apply Loctite 542 to the threads of the detent when
installing to the spool.
Apply Castrol “Spheerol” TN grease to the inside of the
spring cover.

C2251

Beveled seal washer

C2252

Spool

Apply Loctite 542

C2238

Spool O-ring

Spool spring
and bushings

Detent

1-28

Center return cover

Detent ball carrier

Tapered
cup

Detent balls

C2242

1

CONTROL VALVE 1.3

C2249

C2250

O-Ring and seat

O-Ring and seat

Spool bores

Disassembly / Repair (cont’d)

11 When installing the detent to the control valve spool,
apply Loctite type 252 to the threads. Tighten the detent
to the spool at 24 Nm (17.7 lbs / ft).

12 Install the spring return / centering cover and tighten
the mounting screws evenly to 6.6 Nm (4.9 lbs / ft).
Install the end cap to the cover and tighten to 9.8 Nm
(7.2 lbs / ft).

Apply Loctite 252

C2254

Detent spring and cap

C2258

1-29

HYDRAULIC CYLINDERS 1.4

Lift cylinder shown

15

C1179

14

7

6

5

4

3

8

2

9

10

11

12

13

1. O-ring 9. Piston part “B” (front)

2. Wiper seal 10 Grease fitting

3. Rod seal 11. Cylinder barrel

1

4. Gland O-ring 12. Gland nut

5. Wear ring 13. Cylinder rod

6. Piston seal 14. Lock nut

7. Wear ring 15. Grease fitting

8. Piston part “A” (rear)

General Information

All cylinders are a double acting, designed to extend and
retract under pressure.
The piston rods, which are made of high strength
distortion free material, are precision ground and hard
chrome plated. The cylinders barrels are micro honed to
close tolerance,straightness and smooth finish for long
piston packing seal life.
All cylinders have a 2 piece piston assembly made of
ductile iron and a polypac seal arrangement consisting of
a piston seal and 2 wear rings.
The rod seal is a “U” cup design, with the “U” facing the
pressurized oil.The rod wiper keeps foreign matter from
entering the cylinder by wiping the rod clean as the
cylinder retracts.

1-30

The gland nut seal is of an “O” - ring design. This seal
keeps the oil from leaking around the gland nut and
cylinder barrel threads.
Certain cylinders have spacers in them. These spacers are
used to limit the stroke of the rod.
Some cylinders also have replaceable hardened bushings
in the pivot areas that can be serviced when worn out.

HYDRAULIC CYLINDERS 1.4

1

Testing the Piston Seals

If the boom or bucket cylinders drift down with the
control valve spools in the neutral position, and with no
external leaks in the hydraulic system, the following test
will indicate if oil is leaking by the cylinder piston seals.
With the hydraulic oil at operating temperature and a
fully loaded attachment, check that the cylinders do not
drop more than 1.5 inches every 3 minutes with the
engine off. Before performing this test, ensure the control
linkages are not binding and the hydraulic control valve
spools are centering in the neutral position. If the test has
proven excessive leak down the cylinders may be further
tested in the following manner.

IMPORTANT

Allowable boom or bucket cylinder drop: 1.5’’ in
3 minutes, @ loaded rating and operating
temperature.

Fixed end

C2356

Fixed end

WARNING

Never repair or tighten hydraulic lines while the
engine is operating or the system is under pressure.

1 This test must be performed with the engine running.
Remove any attachment and block the loader securely
with all 4 wheels off the ground.
2 Retract the cylinder(s) to be tested. Shut off the
engine and cycle the controls to release the hydraulic
pressure.
3 Disconnect the hose from the fixed end of the
cylinder to be tested. Cap the hose with a steel plug to
prevent system charge pressure from escaping the open
circuit and to prevent contamination.
4 Start the engine and cycle the control(s) as to retract
the cylinder. Do not over activate the controls as to place
in the detent position. Have a container can ready to catch
any waste oil to prevent environmental contamination.
5 Repeat for all both cylinders.
6 If oil leaks from the cylinder port the seals are bad
and need replacement. If no oil leaks you may need to
check the load check valves or spool wear in the
hydraulic control valve.
7 Connect the hydraulic hose to the cylinder ports if no
further servicing is required.

C2351

WARNING

Use extreme caution when checking the hydraulic
system for leaks. Fluid under pressure can penetrate
the skin and cause serious injury. Never use your
hands to check for leaks.

Hydraulics under liftarm step

C1336

1-31

HYDRAULIC CYLINDERS 1.4

Lift Cylinder Replacement

IMPORTANT

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs on
all open lines and ports.

The following procedure will assist you in the cylinder
removal.
For removal of the boom cylinders:

1 Lower the boom arms, stop the engine and cycle the
controls to relieve any hydraulic back pressure in the
system. Lock the control in the float or detent position.

2 Remove the hydraulic hoses from the cylinder. (fig.
C2356) Cap all open ports and lines to prevent
contamination.

3 Remove the lock nut and bolt from both mounting
pins. (fig. C2413, C1864)

4 Remove the front pivot pin by pushing the pin out
from behind the boom arm, out toward you. (fig. C1876)
With an appropriate punch and hammer to prevent
brooming of the pin, remove the rear pin. (fig. C1877)
Brooming the pin makes it difficult to remove.

Disconnect hoses

C2356

Remove bolt

C2413

Remove front pin

5 Remove the cylinder from the loader.

6 Upon replacement, inspect the pivot pins and
cylinder bushings for any wear. Replace if necessary.
Reverse order above for installation.

7 Upon start up, check for system leaks and replenish
the hydraulic reservoir as required.

WARNING

Use extreme caution when checking the hydraulic
system for leaks. Fluid under pressure can penetrate
the skin and cause serious injury. Never tighten or
repair hydraulic lines while the engine is operating.

C1876

Remove rear pin

C1877

1-32

1

HYDRAULIC CYLINDERS 1.4

Tilt cylinder Replacement

For tilt cylinder removal:

1 Lower the boom arms, remove any attachment and
extend the tilt cylinders. Shut off the engine and cycle the
controls to relieve excessive back pressure in the
hydraulic system.

2 Loosen or remove the hydraulic hoses from hydraulic
tubing under the boom arm step if you are changing the
hoses also. (fig. C1336)

3 Remove the hydraulic hoses from the tilt cylinder.
Plug and or cap all open ports or lines to prevent
contamination. (fig. C2414a)

4 Remove the lock nuts from the bolts retaining the
pivot pins to the loader and remove the bolts. (fig.
C2414)

5 Remove the pivot pins.

6 Remove the cylinder from the loader.

7 Upon reassembly, inspect the pivot pins and bushings
for wear and replace as required. Reverse order for
cylinder installation.

Bolts

C2414

Hoses underneath the boom arm step area

C1336

8 Upon start up, check for system leaks and replenish
the hydraulic oil reservoir as required.

WARNING

Use extreme caution when checking the hydraulic
system for leaks. Fluid under pressure can penetrate
the skin and cause serious injury. Never tighten or
repair hydraulic lines while the engine is operating.

Remove hoses

C2414a

1-33

HYDRAULIC CYLINDERS 1.4

Cylinder Disassembly

Before Attempting repairs to the hydraulic cylinder, clean
the body with a suitable solvent. Ensure all openings are
plugged to prevent solvent from entering the cylinder.

1 Remove the cylinder as outlined previously.
2 Place the base end of the cylinder in a vise and
support the front end of the body. Remove the plugs from
the hose ports. (fig. C125)

3 Loosen the gland nut from the cylinder barrel using a
spanner wrench. The gland nut threads are coated with
loctite bonding agent at time of assembly. It may be
necessary to apply heat to the gland nut and cylinder
barrel threaded area, with a torch, to ease removal. (fig.
C125)

4 Remove the gland nut, rod and piston seal assembly
from the barrel. (fig. C329)

5 Place the cylinder rod bushing end in a vise and
remove the lock nut from the rod. (fig. C128)

C125

C329

Remove lock nut

6 Remove the 2 piece piston assembly from the rod.
(fig. C126)

7 NOTE: Some piston assemblies rear piston parts are
threaded onto the rod. You will need to use a spanner
wrench to remove this type of rear piston.

1-34

C128

C126

HYDRAULIC CYLINDERS 1.4

1

8 Depending on the design of the rear piston, non
threaded type, remove and discard the o-ring seal from
the end of the cylinder rod. (fig. C127)

9 Remove the gland nut assembly from the cylinder
rod. (fig. C330)

O-ring seal

C127

10 Remove and discard the wiper seal, rod seal and o­ring seals and teflon back up washer, (if used), from the
gland nut assembly. (fig. C612) NOTE: Some seal
designs may vary from illustration

11 Remove and discard the wear rings and piston seal
from the piston assembly. (fig. C130)

Gland nut

C330

Gland o-ring

Gland nut

Wiper seal

Back up
washer

Rod seal

C612

C130

1-35

HYDRAULIC CYLINDERS 1.4

Cylinder Inspection

1 Inspect the cylinder rod for scratches, dents and other
damage. Minor rod damage may be repaired using a fine
abrasive. Major scratches or dents are not repairable and
the rod must be replaced. The chrome surface must be
intact to provide a rust resistant surface. Blemishes on the
rod will damage the rod seal and wiper and will cause
leaking after a short period of use.
2 Inspect the cylinder rod threads. The threads must be
in good condition to withstand the high torque required to
secure the piston assembly to the rod.
3 Inspect the gland nut for nicks, burrs or other
damage. Minor damage may be repaired using a fine
abrasive.

Cylinder Assembly

1 Install a new gland nut rod seal. Form the seal into
an oval shape and place it into the gland nut, with the “U”
side of the seal facing the barrel end, and slip the seal into
the groove. (fig. C129, C131)

Smooth down edges that could damage seals and cause
leakage.
4 Inspect the gland nut threads for damage.
5 Inspect the piston assembly for damage. Remove
minor scratches or damage with a fine abrasive.
6 Using a suitable light, inspect the cylinder barrel bore
for scratches, dents, burrs or any other damage. Replace
the cylinder barrel if there is any evidence of damage.
7 Inspect the cylinder barrel threads for damage. The
threads must be in good condition to withstand the high
torque required to secure the gland nut assembly to the
cylinder barrel.

2 Install a new wiper seal in the gland nut. (fig. C129,
C131)
3 Install a new gland nut o-ring seal. (fig. C129, C131)

4 Apply system oil to the cylinder rod and assemble
the gland nut assembly to the rod. (fig. C132)

C129

C131

1-36

C132

HYDRAULIC CYLINDERS 1.4

1

5 Install a new o-ring seal on the cylinder rod if used.
Some cylinder rod are fully threaded here to
accommodate a threaded type rear piston part. (fig. C133)

6 Install new wear rings and piston seal to the the 2
piece piston assembly. (fig. C130)

C133

7 Install the piton assembly to the cylinder rod. Some
rear piston assemblies are threaded onto the cylinder rod.
Use a spanner wrench to install the rear piston part to the
cylinder rod. Torque the lock nut to the rod at 150 ft / lbs
(204 N.m.). (fig. C128)
8 Make sure the inside bore of the cylinder barrel is
clean. Lubricate the inside of the barrel with system oil.
Do not get oil into the threaded area of the barrel.

9 Lubricate the piston seal assembly with system oil
and install the cylinder rod and piston assembly to the
cylinder barrel. (fig. C329)
10 Apply loctite 242 to the gland nut threads and tighten
the gland nut using a spanner wrench. Tighten the gland
nut as much as you can using the spanner wrench. Make
sure the threaded area of the gland nut and cylinder barrel
are free of oil before applying the loctite bonding
adhesive.
11 Assemble the cylinder to the loader. Use teflon tape
or equivalent on the threads of the hydraulic hose ends, if
the hose ends are of the taper pipe thread type.

C130

C128

C329

1-37

HYDRAULIC OIL FILTER 1.5

General Information

The hydraulic oil filter is located in the engine
compartment, accessed by opening the rear door and
lifting the engine compartment cover. The filter is
mounted on the left side, on the oil reservoir.
All oil returning from the control valve is filtered before
being used up by the hydraulic system.
The hydraulic oil filter is a spin on type with a 10 micron
rating. The filter material is a resin impregnated cellulose
which features an accordion pleated design to provide
maximum filtration area. Only Thomas approved filters
should be used.
The filter mounting head has a built in bypass valve that
diverts oil around the filter when more than 25 psi (34
nm) differential pressure is required to force oil through
the filter.

Filter Replacement

The hydraulic oil filter must be changed after the first
50 hours of operation and every 150 hours thereafter,
or sooner if the pressure gauge dictates.

1 Lower the boom arms, shut off the engine and
engage the parking brake.
2 Open the rear door and raise the engine compartment
cover to gain access to the hydraulic filter. (fig. C2347,
C2354)
3 Clean the area of excess dirt if necessary to prevent
contaminating the new filter when installing
4 Remove the hydraulic oil filter using a proper sized
filter wrench. Check to make sure the o-ring seal has
come off with the used filter. (fig. C1868)
5 Lubricate the new filter seal with clean system oil.
6 Install the filter and fit hand tight.
7 After start up, check the system for oil leaks.
Replenish the oil reservoir as required with API 10W30
class SE / CD. (fig. C892, C1108)

Access the engine compartment

C2347

Pressure gauge

Hydraulic oil filter

Oil level site gauge

C2354

Check seal

C1868

Filler cap

WARNING

Never repair or tighten hydraulic lines while the
engine is operating or the system is under pressure.

1-38

Oil level
site gauge

C1108C892

HYDRAULIC OIL COOLER 1.6

1

General Information

The hydraulic oil cooler is mounted to the inside of the
rear door. (fig. C2932) Oil returning from the control
valve is circulated through the oil cooler before being
sent on to other parts of the hydraulic system.
An engine driven cooling fan drives air through the oil
cooler when the rear door is closed.
The oil cooler is rated at 250 BTU / minute.
The oil cooler should be checked daily for dirt build up
on the cooling fins. If air flow is restricted through the
cooling fins, over heating of the hydraulic system may
occur. Clean any dirt build up with compressed air. Flush
with water if necessary.

To avoid eye injury,

WARNING

Cooler Replacement

1 Lower the boom arms, engage the parking brake and
shut off the engine.
2 Open the rear door.
3 Connect a vacuum system to the oil reservoir filler
spout, if available, or drain the hydraulic oil reservoir. Be
prepared to contain 34 liters of fluid (9 gal). Use clean
containers if the oil is to be reused.
4 Remove the cooler hoses. Plug the open hoses and
cooler ports to prevent contamination.
5 Remove the cooler from the rear door.
6 Remove the fittings from the oil cooler.
7 Inspect the fitting o-rings for damage and replace if
necessary.
8 Install the fittings into the new or repaired oil cooler
following the torque chart on section 1.10. Be sure to
support the cooler as the fittings are tightened to prevent
damaging the cooler.
9 Replace the cooler & cooler lines. Follow the torque
chart on section 1.10 when tightening the hydraulic hoses.
10 Replenish the hydraulic fluid as required. Check for
system leaks and check the fit of the shroud seal to the
engine radiator. Adjust if necessary.

always use safety goggles
when cleaning with
compressed air.

C2932

Engine driven cooling fan

C1872

Upper Radiator Mount

C2933

1-39

HYDRAULIC OIL RESERVOIR 1.7

General Information

The hydraulic oil reservoir is located at the rear of the
loader on the left hand side. (fig. C2934) The reservoir is
completely separated from all chain and gear drives to
eliminate contamination. A magnetic drain plug is
installed in the bottom of the reservoir, and a magnet is
attached to the 100 micron suction filter, to assist in
removing metal particles from the oil.
Oil level is checked through a site gauge located just
inside the engine compartment, left hand side, on the oil
reservoir. The proper fill level is marked by a line and
should be checked daily. (fig. C2354)
The oil reservoir fill cap is located at the top of the
reservoir. (fig. C2355) The oil fill cap assembly has a 30
micron screen to catch larger particles of contaminant
before entering the reservoir, but always use oil filtered

through a 10 micron min. filter for replenishing the
hydraulic reservoir. The oil fill cap is also a reservoir

vent, or breather, and contains a 10 micron filter to
remove air borne particles.

Checking The Oil Level

1 Check the reservoir oil level with the loader on level
ground.
2 Lower the boom arms, retract the cylinders and
engage the parking brake. Shut off the engine.
3 Open the rear door. (fig. C2934)
4 Check the oil level in the sight gauge. (fig. C2354)
5 If oil is visible approximately mid way in the sight
gauge, the level is correct.

Hydraulic oil reservoir

C2934

Reservoir sight gauge

C2354

IMPORTANT

Always use filtered oil to replenish the hydraulic
system.

Adding Oil

1 Remove the bolt, or lock, on the reservoir filler cap.
2 Open the filler cap. (fig. C2355)
3 Inspect the filler screen in the filler neck for damage.
If the filler screen is damaged, replace it.
4 Using a clean container, add 10W30 API class SE /
CD oil.
5 Replace the filler cap and replace the bolt, or
padlock, in the cap to prevent vandalism.

1-40

Reservoir filler cap

C2355

HYDRAULIC OIL RESERVOIR 1.7

1

Servicing The Oil Reservoir

Change the hydraulic oil, change the suction screen
element and clean the magnet in the tank after every 1000
operating hours or if the oil has become contaminated or
after any major hydrostatic drive system repair.

1 Lower the boom arms, shut off the engine and
engage the parking brake.

2 Remove the magnetic drain plug located at the
bottom of the hydraulic oil reservoir. (fig. C1034) Clean
any metal particles that may be attached to the magnet.
Have containers ready to hold approximately 10 gallons
(45 £) of fluid. Replace the drain plug using teflon sealing
tape or liquid type sealant on the plug threads.

3 Access the suction screen element in the hydraulic
reservoir by removing the inspection cover on the
reservoir, located in the engine compartment. (fig. C2357)
Clean the excess silicone from the cover and reservoir.

Hydraulic reservoir drain

C1034

Hydraulic reservoir inspection cover

4 Remove the suction screen element from the
reservoir by turning counter clockwise. (fig. C1769,
C1777)

5 Remove and clean the magnet attached to the suction
element. (fig. C1769)

6 Install the magnet onto a new suction element and
install the suction element.

7 Apply silicone around the inspection hole and install
the inspection cover to the reservoir. Do not over tighten
the mounting nuts. Maximum torque is 18 ft / lbs (24
N.m.).

8 Fill the reservoir to the proper level with 10W30 API
classification SE / CD oil, approximately 13 gallons or 50
liters.

C2357

Suction element

Magnet

C1769

Suction element

C1777

1-41

TROUBLE SHOOTING 1.8

Problem Cause Corrective Action Section

Loss of hydraulic
power (no flow from
the gear pump).

Loss of hydraulic
power (full flow from
gear pump).

Hydraulic action jerky. Reservoir low on oil. Check for leaks. Fill the reservoir to the proper level. 1.8

Boom raises slowly at
full RPM

Hydraulic cylinders
will not support a load.
(leak down)

Reservoir low on oil. Check for leaks. Fill the reservoir to the proper level. 1.8
Universal joint between

engine and tandem
pump failure.

Gear pump not
functioning.

Splined coupling
failure in the
hydrostatic pump

Electrical failure. Check fuse, switches and wiring.
Auxiliary hydraulics

engaged.
Relief valve failure or

out of adjustment.
Control locks engaged Check fuse, safety switches and valve lock parts.

Control linkages loose
or worn.
Air in hydraulic
system.
Load check valve not
functioning.

Control valve spool
spring return mech­anism not functioning

Reservoir low on oil. Check for leaks. Fill the reservoir to the proper level.
Control linkages loose
or worn.
Auxiliary hydraulics
engaged.

Lifting more than rated
capacity.

Engine RPM too low. Check engine RPM and reset.
Relief valve failure or

out of adjustment.
Cylinder seal(s) failure.

Internal leakage in the
control valve.

Control valve spools
not centering.

External leak between
control valve and
cylinders

Cylinder seal(s) failure
Load check valve not

functioning.

Inspect and replace the damaged parts as required.
Check for proper alignment.

Inspect and replace damaged parts.

See the Sauer Sundstrand Repair Manual BLN 9992.

Disengage the switch.

Check pressure. Adjust or repair as required. 1.4

Inspect, adjust or replace parts.

Check for leaks between the oil reservoir and pump.

Inspect and replace damaged parts. 1.4

Inspect and replace damaged parts. 1.4

Inspect, adjust or replace parts. 4

Disengage the switch.

Reduce the load.

Check pressure. Adjust or repair as required. 1.4

Check seals.
Inspect the control valve and repair as required. 1.4

Check control linkage and control valve spool spring
centering devise.

Inspect and repair.

Check seals.
Inspect and replace damaged parts.

7.11

1.4 / 2.9

2.10

8

4.9

1.4 / 8

4

1.8

4.9

7.11

1.5

1.4 / 4

1.5

1.4

1-42

TROUBLE SHOOTING 1.8

1

Problem Cause Corrective Action Section

Hydraulic oil
overheating.

Reservoir low on oil. Check for leaks and replenish as required. 1.7
Oil cooler plugged or

dirty. (if applicable)
Auxiliary hydraulics

engaged.
Temperature sender

defective.
Relief valve failure or

out of adjustment.
Wrong type of

hydraulic fluid.

Clean the cooling fins.

Disengage.

Replace.

Check pressure, adjust or replace.

Replace.

8

1.4

1.7

TORQUE CHART 1.9

Hydraulic Hose and Fitting Torque Chart

NOTE: all torques are in lbs. / ft (Multiply by 1.36 = N.m.)

HOSE SIZE 37º JIC FITTINGS HOSE SIZE ORB FITTINGS

1/4 9 to 10 1/4 14 to 16
5/16 15 to 16 5/16 18 to 20
3/8 20 to 22 3/8 24 to 26
1/2 30 to 33 1/2 50 to 60
5/8 40 to 44 5/8 72 to 80
3/4 70 to 77 3/4 125 to 135
7/8 82 to 90 7/8 160 to 180
1 55 to 60 1 200 to 220
1 1/4 120 to 132 1 1/4 210 to 280
1 1/2 131 to 144 1 1/2 270 to 360
2 300 to 330

The following torque specifications are for steel ORB fittings into aluminum.

HOSE SIZE ORB FITTINGS HOSE SIZE ORB FITTINGS

1/4 5 to 7 3/4 40 to 45
5/16 8 to 10 7/8 50 to 55
3/8 10 to 12 1 90 to 99
1/2 21 to 24 1 1/4 80to 90
5/8 27 to 30

1-43

NOTES

THOMAS

1-44

2

SECTION 2

HYDROSTATIC DRIVE SYSTEM

Hydrostatic Drive Circuit . . . . . . . . . . . 2.1

Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-2

Specifications . . . . . . . . . . . . . . . . . . . . 2.2

Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-3

General Information . . . . . . . . . . . . . . . 2.3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-4

Trouble Shooting . . . . . . . . . . . . . . . . . 2.4

Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-5 ~ 7

Diagnose Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-8

Pressure Tests . . . . . . . . . . . . . . . . . . . . 2.5

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-9

Towing Procedure . . . . . . . . . . . . . . . . . 2.6

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-10

Flushing The Hydraulic System . . . . . . 2.7

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-11

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-12

Start-up Procedure . . . . . . . . . . . . . . . . 2.8

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-14

Gear Pump Replacement . . . . . . . . . . . 2.9

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-15

Tandem Pump Replacement . . . . . . . . 2.10

Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-16

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .pg. 2-17

Tandem Pump Parts Diagram . . . . . . . 2.11

Parts Illustrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-20 ~ 23

Drive Motor . . . . . . . . . . . . . . . . . . . . 2.12

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-24

Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-28

Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-30

Parts Illustration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-32 ~ 33

Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-34

Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pg. 2-42

2-1

HYDROSTATIC CIRCUIT 2.1

Hydrostatic Circuit Schematic

C1007

2-2

2

SPECIFICATIONS 2.2

Hydrostatic Tandem Pump

Pump Type . . . . . . . . . . . . . . . . . . . . Variable Displacement, Reversible Piston

Brand Name of Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sauer Sundstrand

Series / Model Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 / M25 PT

No. Of Drive Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 (TWO)

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tandem

Rotation (viewed from shaft end) . . . . . . . . . . . . . . . . . . . . . . . . . . . Clockwise

Operating Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3000 RPM (+ / - 50 RPM)

Pump Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 cu. in. (25cc)

Minimum Pump Output (flow) . . . . . . . . 9.5 gal. (36L) / Minute @ 1800RPM

. . . . . . . . . . . . . . . . . @ 2000 PSI (137.8 Bar) Over Measured Charge Pressure

No. Of Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 (TWO)

Relief Valve Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Bar (3625 PSI)

Max. Allowable Case Pressure . . . . . . . . . . . . . . . . . . . . . . . . . 25 PSI (1.7 Bar)

Charge Pump Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N / A

Charge Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 PSI Min. (13.8 Bar)

Hydrostatic Repair Manual . . . . . . . . . . . . . . . . . . . . . . . . Thomas P / N 44232

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sauer Sundstrand P / N BLN-9992

Hydraulic Drive Motor

Drive Motor Type . . . . . . . . . . . . . . . . . . . . . Geroler Torque Motor With Brake

Brand Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Danfoss

Series Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OMT 315 FLV

Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dual

No. Of Drive Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 (TWO)

Drive Motor Displacement . . . . . . . . . . . . . . . . . . . . . . . 19.9 cu. in. (326.3cm3)

Max. Case Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 PSI (1.7 Bar)

Reservoir

Fluid Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10w30 API Class SE / CD Oil

Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 gal (43L)

Reservoir Filtration . . . . . . . . . . . . . . . . . . . . One 100 Micron Screen Element

Hydraulic Oil Filtration . . . . . . . . . . . . . . . . . . . . . . . . One 10 Micron Element

Hydraulic Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P / N 35243

2-3

GENERAL INFORMATION 2.3

Clockwise input
shaft rotation

High pressure

C1700

Counterclockwise
swash plate rotation

Charge pressure inlet

Variable displacement
piston pump

Case drain

High pressure

Case drain

Fixed displacement
drive motor

Counterclockwise
output shaft rotation

The driveshaft of the piston pump is rotated by the
engine. The piston block which is splined to the drive­shaft also turns. The piston block, rotating group, consists
of 9 piston assemblies which have free swiveling shoes
swagged on the ball end of each piston assembly. The
shoe end of the piston rides against the smooth machined
surface of the swashplate. With the swashplate in the neu­tral position, the piston assemblies do not reciprocate in
the piston block, but are rotating. No oil is drawn into or
discharged from the pump. The pump is in a zero dis­placement position and the loader remains stationary.
With the swashplate in the neutral position the pressure of
the charge oil, which ranges from 200 to 280 psi (13.8 -

19.3 Bar), is able to unseat both check valves and supply
oil to both sides of the pump because of the balance in
pressure. Very little charge oil volume is required in the
neutral position so the excess oil is bypassed over the
charge pressure relief valve and recirculated back to the
reservoir. The oil that leaks internally in the pump and
motor collects in their body housings and is returned to
the reservoir by external case drain in the pump and
motors. This leakage oil is the only oil the charge check
replenishes. This makes the design a closed loop system.
As the steering lever is moved forward, or reverse, the
loader starts a directional movement. As the swashplate
begins to move, the piston assemblies start to reciprocate
in the piston block. As the steering lever continues further
movement the cam angle increases, the pistons recipro ­cate further, more oil is pumped and the speed of the
loader is increased.

When the swashplate begins to move the check valve on
the discharge, or pressure, side seats because of the high­er pressure differential. The other check valve remains
open on the intake or low pressure side to continue sup ­plying the closed loop system with charge oil.
The drive motor, which is a fixed displacement type,
delivers a constant output torque for a given pressure
throughout the speed range of the motor.
The movement of the pump swashplate, forward or
reverse, controls the direction of the drive motor rotation.
The function of the pressure relief valve is to relieve the
pressure side of the system of excessive high pressure
when the loader encounters a heavy load or stalls out.
When the relief valve senses an over load it unseats,
allowing excess pressure and volume to flow into the low
pressure side of the pump. A small volume of oil starts to
flow across to the other relief valve. This relief valve is
exposed to the low pressure on the intake side of the
pump and is seated by the spring tension within the relief
valve body.
The small volume of oil being bypassed is enough to
unseat the relief valve and let it recirculate back into the
inlet side of the pump. As the pressure continues to build
on the pressure side, a larger volume of oil flows and at a
greater speed through the drilled orifice in the relief valve
cartridge, causing a pressure drop inside the relief valve.
The surrounding pressure is now able to unseat the relief
valve and bypass maximum volume of oil. The system
reliefs function the same for both sides of the system.

2-4

2

TROUBLE SHOOTING 2.4

Symptom: Neutral Difficult Or Impossible To Find

Inspect external
control linkage

Defective

Repair or

replace

OK

Inspect servo
control ( if used )

Defective

Repair or

replace

Symptom: System Operating Hot

Check oil level
in reservoir

Inspect heat
exchanger

OKOK

Check charge
pressure

OK

Fill to proper
level

Inspect charge
pump

Repair or

replace

Replace pump
and motor

DefectiveBelow level

Repair or
replace

OK OK

OK

Inspect inlet
screen or filter

CloggedDefective

Replace

Inspect motor

Defective High

Repair or
replace

OK

Low

Inspect charge
relief valve

Defective

Repair or
replace

Check system
pressure

Reduce system
load

2-5

TROUBLE SHOOTING 2.4

OK

Symptom: Operates In One Direction Only

Inspect external

control linkage

Defective

Repair or

replace

OK OK

Inspect servo
control ( if used )

Defective

Repair or

replace

Symptom: System Response Sluggish

Check charge
pressure

OK

Inspect servo
control ( if used )

OK

Inspect system
relief valves

Defective

Repair or

replace

Inspect
motor

2-6

Low

Inspect charge
relief valve

Defective

Repair or

replace

Defective

Inspect inlet
screen or filter

Clogged

Replace

Repair or

replace

OK

Inspect charge
pump

Defective

Repair or

replace

Defective

Repair or

replace

OKOK

Replace pump
and motor

2

TROUBLE SHOOTING 2.4

Symptom: System Will Not Operate In Either Direction

OK

Check oil level
in reservoir

Below level

Fill to proper

level

Inspect charge
pump

Defective Clogged

Repair or

replace

Replace pump
and motor

OK OK

Inspect motor

Check external
control linkage

Defective

Repair or

replace

Inspect inlet
screen or filter

Replace

OKOK OK

Inspect servo con -

trol ( if used )

OKOK

Check charge
pressure

Low

OK

Inspect charge
relief valve

Defective

Repair or

replace

Check sys­tem pressure

Defective Defective High

Repair or

replace

Repair or

replace

Reduce sys-

tem load

2-7

TROUBLE SHOOTING 2.4

C1699

C1704

C1698

Pressure gauges

Vacuum gauge
30in. Hg

Adapter fittings

C1697

Caps and plugs

0 - 500PSI (34.5Bar) 0 - 5000PSI (345Bar)

System Diagnosing Steps And Special Tools

1 Check oil level in reservoir:

a .fill to proper level as marked on site tube.

2 Inspect external control linkage for:

a. misadjustment or disconnection
b. binding, bending or breakage
c. misadjusted, damaged or broken hydroback

3 Inspect servo control valve for: (if used)

a. proper inlet pressure
b. misadjusted or damaged neutral return spring
c. galled or stuck control spool
d. galled or stuck servo piston

4 Inspect heat exchanger for:

a. obstructed air flow
b. improper plumbing (inlet to outlet)
c. obstructed fluid flow

5 Inspect inlet filter or screen for:

a. plugged or clogged screen or filter
b. obstructed inlet or outlet
c. open inlet to charge pump (open line)

6 Check charge pressure:

a. follow test procedures section 2.5

7 Inspect charge relief valve for:

a. poppet held of seat
b. damaged or broken spring
c. damaged valve seat
d. improper charge relief setting

8 Inspect charge pump for:

a. broken or missing drive coupling
b. damaged or missing o-rings
c. galled or broken geroter set

9 Inspect system relief valves for:

a. damaged or broken springs
b. valve held of seat
c. damaged valve seat
d. improper pressure relief settings

10 Check system pressure:

a. follow test procedures section 2.5

11 Inspect hydraulic motor for:

a. disconnected coupling

2-8

2

PRESSURE TESTS 2.5

The following photos show the various port locations
available on the hydrostatic tandem pump for checking
system pressure.
Completing these pressure test will diagnose any mechan ­ical problem in the hydrostatic system.

WARNING

Use caution when dealing with hydraulic fluid
under pressure. Escaping fluid under pressure can
penetrate the skin and cause serious injury.

Installing a gauge into the high pressure port ‘A’ or ‘B’ ,
will verify the status of the high pressure relief valves.
Checking the pressure at port ‘C’ will give accurate
charge pressure reading.
Checking the pressure at port ‘D’ will verify case drain
pressure.
Measuring the vacuum at the charge pump inlet can help
locate in in the inlet lines and filters. It would be neces­sary to tee into the charge pump line fitting.
Snubbers are recommended to protect the gauges from
pressure spikes. Frequent gauge calibration is necessary
to insure accuracy.

Gauge Information

System

A

Pressure
Port ‘A’
System

B

Pressure
Port ‘B’
Charge

C

Pressure
Port
Case
Pressure

D

Port
Charge
Pump Inlet

E

Vacuum

Tandem pump flow can also measure pump performance.
1 Connect a flow meter between the high pressure
ports, one section at a time.
2 Start the engine and increase operating speed
between 1775 ~ 1800 RPM.
3 Restrict the flow to show 2000 PSI (137.8 Bar) over
charge inlet pressure.
Example: Charge pressure = 220 PSI (15.2 Bar) Gauge
pressure reading would need to be 2220 PSI (153 Bar).
4 Minimum flow reading should be 9.5gal / min. (36L /
min).

10,000 PSI Gauge (690 Bar)
9/16 - 18 O-Ring Fitting

10,000 PSI Gauge (690 Bar)
9/16 - O-Ring Fitting

500 PSI Gauge (34.5 Bar)
Tee Into Charge Filter Outlet Line

500 PSI Gauge (34.5 Bar)
1 - 1/16 - 12 O-Ring Fitting

Vacuum Gauge (30 in. Hg)
Tee Into Charge Pump Inlet

C1794

C1795

C1796

Illustrations are of an internal charge pump model.
Actual model in machine may vary.

WARNING

Raise the machine securely from the ground before
performing system checks to prevent sudden move­ment.

A complete testing kit is available from Thomas, p/n
44365, that contains gauges, hoses and adapters for
Sauer Sundstrand model pumps.

2-9

TOWING 2.6

C2359

C2362

Relief valve location

Brake release plunger

Brake valve

2 located bottom side

In an event the loader has malfunctioned or failed, the
loader may be moved a short distance by following the
procedure:

2-10

2

FLUSHING THE HYDRAULIC SYSTEM 2.7

General Information

Contamination in the hydraulic system is a major cause of
component failure. Contamination can enter the hydraulic
system in any of the following ways.
1 When draining the hydraulic system.
2 When disassembling components.
3 Making auxiliary connections with dirty couplers.
4 Normal component wear.
5 Component failure

Contamination Types

There are 2 types of contamination, microscopic, or non
visible, and visible. Microscopic contamination is sus­pended in the fluid and moves freely through the
hydraulic circuits. Examples of problems caused by
microscopic contaminates include the following:
1 Cylinder rod seal leaks.
2 Control valve spools do not return to neutral.
3 Hydraulic system has a high operating temperature.
4 Components wear rapidly.

The best way to remove contaminates from the hydrostat­ic drive system is to disassemble each component and
flush and clean thoroughly.
The hydraulic control circuits may be cleaned by attach­ing a suitable hydraulic filter to the auxiliary couplings
and circulating the fluid through it.

Visible contamination is foreign material that can be
found by sight, touch or odor. Some examples of visible
contamination include the following:
1 Particles of metal or dirt in the oil.
2 Air in the oil.
3 Odor of burned oil.
4 Water in the oil.

2-11

FLUSHING THE HYDRAULIC SYSTEM 2.7

Cleaning The System

The first step in cleaning the hydraulic system is to deter­mine if you have visible or microscopic contamination.
If the contamination is visible, do the following steps:
1 Change the hydraulic oil by removing the drain plug
in the bottom of the hydraulic oil reservoir. (fig. C1034)
Be prepared to contain approximately 30 litres of fluid.
2 Check the extent of the contamination by disassem­bling 1 each of the hydraulic cylinders. Check the cylin­ders for damage. Repair or replace the cylinders as
required. If you determine the damage was caused by
severe contamination and is not the result of normal wear,
it will be necessary to remove, clean and repair all valves,
pumps, lines, cylinders, etc.
3 Replace all hydraulic filters.
If the contamination is determined to be microscopic, per­form the following steps:
1 Change the hydraulic oil by removing the plug in the
bottom of the oil reservoir. (fig. C1034) Be prepared to
contain approximately 30 litres of fluid.
2 Connect an external 10 micron filtering system, capa­ble of sustaining minimum of 2000 PSI (138 Bar) and has
a back pressure gauge, to the auxiliary couplings. (fig.
C2351, C1688)
3 Start the engine and let it idle at approximately half
throttle.

WARNING

Hydraulic reservoir

Oil drain plug

C1034

Flush the fluid to an external trap filter

Pressure out

C2351

Replace the hydraulic filter

C1688

Be sure to use a filtering system capable of handling
the pressure of the hydraulic system.

4 Engage the auxiliary circuit. Check to make sure the
filtering system is not over taxed by the loaders hydraulic
system pressure. Adjust engine idle accordingly to match
the filtering systems capacity. This may vary as the filter
becomes dirty, you may need to decrease engine RPM.
Circulate the oil through filter for 30 minutes.
5 As the oil is being circulated through the auxiliary
circuit, raise the liftarms up and down in full stroke
cycles. Repeat this exercise for 15 minutes.
6 Cycle the bucket tilt cylinders in the same manner as
above. Repeat the exercise, in full extension and retrac­tion, for 15 minutes.
7 Install new hydraulic oil filters. (fig. C2354a)
8 Start the engine and check for leaks. Replenish the
hydraulic oil reservoir as required. (fig. C2354b)

2-12

C2354a

Hydraulic reservoir sight gauge

Oil level

C2354b

2

FLUSHING THE HYDRAULIC SYSTEM 2.7

For flushing water from the hydraulic system, perform
the following procedures:

WARNING

Be sure attachments are removed and liftarms are
in the lowered position.

1 Remove any attachment.
2 Make sure all cylinders are fully retracted.
3 Change the hydraulic fluid. (fig. C1034)
4 Change the hydraulic filter. (fig. C2354)
5 Disconnect the hydraulic lines from one set of cylin­ders. (fig. C2356, C1336)
6 Start the engine and set to the lowest idle.
7 Have someone hold the open hydraulic lines into a
container. Stroke the foot pedals, or hand operated, con ­trols slowly. Continue to repeat this cycle until the oil
comes out clear. Repeat for opposite set of cylinders.

WARNING

Use caution when dealing with hydraulic fluid
under pressure. Escaping fluid under pressure can
penetrate the skin and cause serious injury.

8 Attach a hose and couplings to the auxiliary circuit.
Engage the auxiliary hydraulics, forward and reverse,
until the oil flows clear.

IMPORTANT

Reservoir drain plug

C1034

Replace hydraulic filter

C2354

Disconnect hydraulic lines

Check the hydraulic oil frequently during this proce­dure. Replenish as required.

9 Connect 1 hose each, on each cylinder, to the fixed
end of the cylinder barrel.
10 Move the foot pedal or control lever to extend the
cylinder rods. This will flush the oil from inside the cylin ­der barrels. Be prepared to contain the waste oil.
11 Stop the engine.
12 Connect the hydraulic hoses to the rod end of the
cylinder barrel.
13 Replenish the hydraulic oil as required.
14 Replace the hydraulic filter.

IMPORTANT

Please contain and dispose of waste oil in an envi­ronmentally friendly manner.

C2356

Disconnect hydraulic lines

C1336

2-13

The following start-up procedure should always be

C2607

Solenoid wire connector

Reservoir sight gauge

Reservoir filler cap

adhered to when starting up a new installation or when
restarting after pump repairs have been made.
1 Fill the hydraulic oil reservoir to the proper level.
(fig. C2354)

START-UP PROCEDURE 2.8

2 The inlet hose from the oil reservoir to the charge
should be filled with oil prior to starting.

3 Check inlet and pressure hose fittings for proper
tightness prior to starting.

4 The pump must be filled prior to start-up with fil­tered oil. Fill the pump by pouring oil into the side case
drain port. (fig. C1795 location “D”)

5 Disconnect the engine stop solenoid wiring connec­tor. (fig. C2607)

6 Turn the engine over by engaging the starter. Repeat
this step, turning the engine over in 15 second interval, 5
or 6 times. This will fill the rest of the hydraulic hoses.

7 Reconnect the engine stop solenoid.

8 Start the engine and let it idle at lowest possible set­ting.

9 Check for leaks and make adjustments as required.
Do not use your hands to check for leaks while the engine
is operating.

C2347

C2354

10 Replenish the hydraulic oil reservoir as required.

11 Start the engine and increase the RPM’s to half throt­tle. Bring the hydraulic fluid up to operating temperature
and make control adjustments as outline in Section 4.

2-14

C1795

2

GEAR PUMP REPLACEMENT 2.9

C1689

Vacuum

Reservoir filler spout

Start the gear pump removal procedure by removing any
attachment, raising the boom arms and engaging the
boom support pins. Shut off the engine.

1 Remove the seat and hydrostatic shield.

2 Attach a vacuum system to the hydraulic oil reservoir
filler location. (fig. C1689) Or drain the oil reservoir. Seal
the threads on the drain plug, if removed, with teflon tape
or a liquid form of pipe sealant before installing.
3 Disconnect the hydraulic hoses from the gear pump.
(fig. C2353a) Remove the pump fittings. Cap all open
hoses to prevent contamination. After capping ends you
may unhook vacuum system from oil reservoir.
4 Remove the 2 bolts holding the gear pump to the
hydrostatic tandem section. (fig. C2353b) Remove the
gear pump.

5 Replace gear pump in reverse order.
6 If the hydraulic system has been contaminated by
pump or other failure you must follow the cleaning proce­dure outlined in section 2.7.
7 Start the engine and check for leaks. Never use your
hands to find leaks.

8 Check the fluid level lin the hydraulic oil reservoir
and replenish as required. (fig. C2354).

2-15

TANDEM PUMP REPLACEMENT 2.10

C2359

High pressure hoses

Tandem case drain hose

Removal

Begin the pump removal by removing any attachment,
raise the boom arms and engage the boom support pins.
Shut off the engine.
1 Remove the seat and hydrostatic shield.

2 Remove the steering lever linkage. Refer to section 4
for removal and replacement information.
3 Remove the gear pump as out lined in section 2.9.
4 Disconnect all the hydraulic hoses. (fig. C2359,
C2610) Marking the hose and fitting location is recom­mended to ease re-assembly. Upon re-assembly, torque
the hydraulic fittings and hoses as outlined in the Torque
Chart in Section 8. Cap all open lines and ports.
5 Remove the hydraulic fittings from the tandem pump
to prevent damage while removing pump. Plug all open
ports and keep the fittings in a clean area. Inspect fittings
and o-rings for damage, replace as required.

6 Loosen the mounting bolts retaining the tandem
pump to the engine bellhousing. (fig. C2608, C2609).
7 Attach a lifting device to the tandem pump. The
pump is fairly heavy, approximately 80 lbs. (36 Kg) It is
highly recommended to use a mechanical lifting device to
assist removal of the tandem pump.

8 Remove the 2 rear mounting bolts. (fig. C2608,
C2609) Remove the tandem pump from the loader.

Refer to the Sauer Sundstrand Repair Manual,
(Thomas p / n 44232 or Sauer Sundstrand p /n BLN -

9992), for complete pump servicing.
Thomas does not cover or handle warranty processing
or repair work performed on the Sauer Sundstrand
product. Warranty work can only be approved and
performed by an authorized Sauer Sundstrand dealer.

2-16

2

TANDEM PUMP REPLACEMENT 2.10

Installation

Upon reassembly, inspect the outside area of the tandem
pump housing for damage that may have occurred in tran­sit or handling.

1 Attach a lifting device to the tandem pump.
2 Apply lithium type grease to the tandem pump input
shaft and the flywheel coupling splines. (fig. C2616).

Not exactly as shown

CAUTION

To prevent personal injury, do not attempt to lift
heavy objects without assistance.

3 Install the tandem pump to the engine bellhousing
lining up the input shaft splines with the flywheel cou­pler. (fig. C2617)
4 Install the 2 mounting bolts. Torque the 2 mounting
bolts to 60 ft/lbs. (82 nm.) Remove the lifting device.

5 Connecting the 4 high pressure drive hoses and fit­tings to the tandem pump can only be accomplished in a
specific sequence. (fig. C2610). Install the bottom 90º
connector to the tandem pump first, then the bottom
straight connector.

A Hose no. 1 connects to the top port of the left hand
drive motor.
B Hose no. 2 connects to the bottom port of the left
hand drive motor.
C* Hose no. 3 is the charge pressure line, connect to the
hose from the hydraulic filter. This fitting must be
installed before connecting hose no. 4 and 5. See fig.
C2611 next page.
D Hose no. 4 connects to the bottom port of the right
hand drive motor.
E Hose no. 5 connects to the top port of the right hand
drive motor.

C2069

Lithium type grease

Flywheel coupling

C2616

Line up pump spline to flywheel coupler

Bellhousing

C2617

High pressure hose layout

Torque the fittings and hoses according to the Torque
Chart in Section 8.

IMPORTANT

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs
on all open line and ports.

2

5

3*

1

4

C2610

2-17

TANDEM PUMP REPLACEMENT 2.10

Installation (continued)

6 Connect the tandem pump case drain fitting and
hose. (fig. C2608) Torque the fittings and hose to the
specifications listed in the Torque Chart in Section 8.

IMPORTANT

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs
on all open line and ports.

7 Connect the auxiliary gear pump outlet fittings and
hoses to the gear pump. (fig. C2353) Follow the Torque
Chart in Section 8 when tightening fittings and hoses.

IMPORTANT

Inspect hydraulic fitting o-rings and flares for marks
or damage. Replace if necessary.

Charge line connection

C2611

Plug

Case drain line

8 Remove the plug on the side of the tandem pump and
fill the tandem pump with filtered. (fig. C2608)

IMPORTANT

Follow the Torque Chart In Section 8 when tighten­ing fittings and hoses.

C2608

To control valve

C2353

From the reservoir

Gear pump

2-18

2

TANDEM PUMP REPLACEMENT 2.10

Installation (continued)

9 Reinstall the steering control linkages as outlined in
Section 4. (fig. C2443).

10 Fill the hydraulic oil reservoir to the proper level.

11 Follow the start up procedure outlined in section 2.8
before attempting to start the loader.

IMPORTANT

Follow the start up procedure outlined in section 2.8
upon restarting after pump repairs or replacement.

WARNING

This start-up procedure must be made with the
loader securely raised off the ground. Changing the
pumps and the steering control linkages has affect­ed the neutral adjustment. Failure to raise the
loader clear of the ground may result in the loader
engaging in motion and possibly causing serious
injury.

Replace control linkage

C2443

Hydraulic reservoir filler cap

C2347

12 Start the loader and check for leaks. Make repairs as
necessary and replenish the hydraulic oil reservoir. Never
use your hands to check for hydraulic leaks.

WARNING

To prevent personal injury never make repairs to
the hydraulic system while the engine is operating.
Use caution when dealing with hydraulic fluid
under pressure. Escaping fluid under pressure can
penetrate the skin and cause serious injury.

13 Make adjustments to the steering controls as
required. Follow the procedures for control adjustments
in Section 4.

Reservoir sight gauge

Fill level

C2354

2-19

TANDEM PUMP PARTS DIAGRAM 2.11

Sauer Sundstrand Series M25 PT Rear Pump (as located in machine)

1

2

3

4

18

26

17

16

13

15

12

14

11

21
22

23

28

22

19

5
6
8

9

20

14

12

24

13

25

26

18

35

36

37

38

39
40

41

48

7

9

10

27

24

25

26

C2621

2-20

29

28

30
31

32

33

34

26

42

43
44

45
46

47

2

TANDEM PUMP PARTS DIAGRAM 2.11

Rear Pump Diagram C2621 Index

1. Retaining ring

2. O-ring seal

3. Seal carrier

4. Input seal

5. Retaining ring

6. Bearing

7. Key (or splined shaft)

8. Drive shaft

9. Bolt

10. Washer

11. Lifting bracket

12. O-ring seal

13. Plug, includes item 12

14. Bearing

15. Seal

16. O-ring seal

17. Trunnion cover

18. Bolt

19. O-ring seal

25. O-ring seal

26. Relief valve, items 24 ~ 26

27. Center section

28. Bearing

29. Coupler

30. Charge relief poppet

31. Charge relief spring

32. Charge relief shims

33. O-ring seal

34. Charge relief, items 30 ~ 33

35. Swashplate

36. Thrust plate

37. Piston assembly

38. Slipper retainer

39. Slipper retainer guide

40. Thrust washer

41. Cylinder block

42. Washer assembly

43. Spring

20. Trunnion cover

21. Housing

22. Dowel pin

23. Gasket

24. O-ring seal

44. Special washer

45. Retaining ring

46. Valve plate, clockwise

47. Spring pin

48. Cylinder block kit, items 37 ~ 45

For further service instructions refer to a Sauer Sundstrand Dealer and request
Service / Repair Manual Part Number BLN 9992 or order P / N 44232 from a
local Thomas Dealer.

2-21

TANDEM PUMP PARTS DIAGRAM 2.11

Sauer Sundstrand Series M25 PT Front Pump (as located in machine)

17

18

19

20

14

15

13

12

11

9

8

10

7

4

13

11

3
2

16

15

8

9

6

5

21

22

23

31

24

25

26

27

28

29

30

C2622

2-22

1

2

TANDEM PUMP PARTS DIAGRAM 2.11

Front Pump Diagram C2622 Index

1. Retaining ring

2. Retaining ring

3. Bearing

4. Drive shaft

5. Bolt

6. Washer

7. Housing

8. O-ring seal

9. Plug, includes item 8

10. Dowel pin

11. Bearing

12. Seal

13. O-ring seal

14. Trunnion cover

15. Bolt

16. Trunnion cover

17. Gasket

18. Pin

19. Valve plate, counter clockwise

20. Retaining ring

21. Special washer

22. Spring

23. Washer assembly

24. Cylinder block

25. Thrust washer

26. Slipper retainer guide

27. Slipper retainer

28. Piston assembly

29. Thrust plate

30. Swash plate

31. Cylinder block kit, items 20 ~ 28

For further service instructions refer to a Sauer Sundstrand Dealer and request
Service / Repair Manual Part Number BLN 9992 or order P / N 44232 from a
local Thomas Dealer.

2-23

DRIVE MOTOR 2.12

General Information

C1129

The basic geroter design uses a combination of mechani ­cal and hydraulic principles that are utilized in the high
torque, low speed motors.

The outer ring (fig. C153) of the geroler assembly is simi ­lar to an internal gear that is held in a fixed position by
securing it to the motor housing. The rotating inner gear,
called a star, orbits inside the secured outer ring.

Because of the different number of teeth on the star and
outer ring, the star rotates in an eccentric circular orbiting
motion from the housing center line. (fig. C154).

C153

2-24

C154

2

DRIVE MOTOR 2.12

A drive shaft is used to transmit the rotation of the star to
the output shaft. The drive shaft has crowned external
splines to match the internal splines in the star and output
shaft. This type of drive is used because the star center
line continuously changes during rotation.

As the star orbits, it causes a continuous opening and
closing of the outer ring fluid pockets. Half of these fluid
pockets are subject to fluid pressure, causing star rotation,
and the opposing half are connected to the return line.

When pressure is introduced into the fluid pockets on the
right side of the star (fig. C156) the output rotation will
be counterclockwise. When the fluid pockets on the left
side of the star are pressurized the output shaft rotation
will be clockwise.

To seal the fluid pockets the torque motor incorporates a
rotating roller type seal. (fig. C157) This type of a rolling
seal reduces friction at the star points providing increased
efficiency and reduced component wear.

C156

C157

2-25

DRIVE MOTOR 2.12

The geroler (fig. C2299), is both a fluid displacement
motor and a gear reducer. It provides 8 times (the number
of star points) greater power per revolution than a gear,
vane or piston type motor. This means that 8 times the
greater torque can be developed at one eighth the speed
without further gear reduction.

8 point star

C2299

Roller (9)

Fluid pockets (9)

Example shown in fig. C166 is one complete star orbit, or
one sixth of the output shaft rotation.The star must travel
through 6 complete orbits for each single rotation of the
output shaft creating a speed reduction of 6 to 1. The use
of 7 fluid power pockets with the 6 to 1 ratio provides 42
fluid power cycles per each complete shaft revolution.

NOTE: Actual star point count is 8. This is only an
example.

2-26

C166

2

DRIVE MOTOR 2.12

For smooth and continuous motor output rotation, the
torque motor utilizes a disc valve which operates in syn ­chronization with the geroler star. The disc valve arrange­ment consist of a stationary balance plate, rotating disc
valve and a stationary valve plate.

The disc valve contains an inlet fluid passage port for
each star valley and a return fluid passage point.

A separate crowned driveshaft is used to synchronize the
disc valve and the geroler star so that they turn as one. To
accept fluid from the disc valve, the valve plate also con ­tains internal porting passages to each outer ring pocket
area.

C1891

C1129

Fluid enters the housing through the inlet port and is
directed to the balance plate. The balance ring contains an
inner and outer seal to separate the high and low pressure
fluid passages. Fluid passes through the stationary bal­ance plate to the rotating disc valve. The rotating disc
valve ports the fluid to the stationary valve plate and the
proper side of the geroler pockets causing the rotor star to
turn.
As the rotor star rotates, and each fluid pocket reaches its
full open position, the return porting in the rotating disc

valve opens to allow the fluid in the pocket are to pass
back through the valve plate, disc valve, balance plate
and out through the housing return port, as the pocket
closes.
The disc valve is timed to the geroler rotor star to govern
the the inlet fluid flow to the output shaft rotation.If the
timing of the disc valve to the geroler star is off one
tooth, the relationship of input fluid flow to output motor
shaft rotation will be reversed.

2-27

DRIVE MOTOR 2.12

Removal

1 Remove any attachment, raise the boom arms and
engage the boom support pins.

WARNING

To prevent personal injury do not work under the
boom arms without the boom supports engaged.

Upper fill check

2 Raise the loader securely off the ground.

3 Remove the wheels on the side to be repaired.

4 Drain the oil from the final drive housing. Be pre­pared to contain approximately 7 litres (1.9 gal) of fluid.
(fig. C1888)

5 Remove the seat and hydrostatic shield.

6 Remove the final drive inspection cover located
between the axles of the final drive housing.(fig. C2424)

7 Disconnect the chain as outlined in Section 3. (fig.
C2424).

8 Remove the 2 high pressure hoses from the drive
motor. (fig. C2360a) Cap the open hose ends and fittings
to prevent contamination.

IMPORTANT

C1888

Oil drain plug

Inspection cover

Connecting links

C2424

High pressure hoses

Brake hoses

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs
on all open line and ports.

9 Disconnect the 2 brake line hoses and cap the hoses
and adapter fittings in the drive motor. (fig. C2360b)

10 Remove the adapter fittings from the drive motor.
Plug the open ports in the drive motor to prevent contam­ination.

2-28

C2360a

Brake hoses

C2082b

2

Removal

C2081

Nuts

C2080

C2079

Apply loctite

C2077

Torque motor mounting bolt

Drive sprocket

12 Remove the jam nuts, mounting nuts and lock wash ­ers from the 4 mounting bolts retaining the drive motor to
the final drive housing. (fig. C2081) Hold the head of the
bolts from inside the final drive housing. (fig. C2077)

13 Remove the drive motor. Seal the drive motor with
silicone upon reassembly.

14 Upon reassembly torque the 4 mounting nuts to 80
lbs / ft.

15 If the drive motor replacement is being performed
because of major parts failure, such as geroler damage,
the hydraulic system must be checked for contamination
and flushed if necessary as outlined in Section 2.7.

DRIVE MOTOR 2.12

2-29

DRIVE MOTOR 2.12

Replacement

1 Clean the mounting areas thoroughly that need to be
sealed with silicone. (fig. C2078, C2424)

2 Apply a bead 1 / 4 of an inch thick around the drive
motor bearing retainer and around each mounting hole.
(fig. C2619)

3 Install the drive motor and sprocket assembly to the
final drive housing.

Clean sealing area

C2078

Clean sealing area

C2424

Apply silicone

4 Install the 4 bolts, lockwashers and mounting nuts
and torque to 80 lbs / ft. (115 nm.)

5 Install the 4 jam nuts. Torque the jam nuts to 40 ~ 60
lbs / ft. (54 ~ 81 nm.)

6 Replace the master link in the dive chain. Section 3.
shows chain replacement procedure.

7 Add oil to the final drive housing unit it trickles out
the upper check plug hole. This will require approximate­ly 7 litres (1.9 gal) of 10w30 API SE/ CD oil. (fig.
C1888)

C2619

Upper check plug

C1888

2-30

2

DRIVE MOTOR 2.12

IMPORTANT

Refer to the torque chart in Section 8 when tighten ­ing hydraulic hoses and fittings

IMPORTANT

Inspect fitting o-rings and flares for marks or dam­age. Replace if necessary.

Brake hoses

8 Install the adapter fittings to the drive motor.

9 Install the brake lines to the drive motor. (fig.
C2360a)

10 Install the high pressure drive hoses. (fig. C2360b)

11 Clean the final drive housing and inspection cover
thoroughly before applying silicone sealant. (fig. C2424)

12 Install the inspection cover. When installing the nuts,
do not over tighten. The mounting torque should not
exceed 11 lbs / ft. (15 N.m.)

14 Start the engine and check for hydraulic leaks. Do
not use your hands to trace hydraulic leaks. Shut off the
engine and inspect each fitting for proper torque.

WARNING

To prevent personal injury never make repairs to
the hydraulic system while the engine is operating.
Use caution when dealing with hydraulic fluid
under pressure. Escaping fluid under pressure can
penetrate the skin and cause serious injury.

C2360a

High pressure hoses

C2360b

Clean sealing area

15 Install the wheels and torque the nuts at 100 to 110
lbs / ft. (136 to 149 nm.)

16 Install shields and seat, let loader down to ground
and test drive to check performance.

C2424

Torque the wheel nuts

C1658

2-31

Parts Illustration

DRIVE MOTOR 2.12

Danfoss OMT FL
Diagram C1892 Index

1. Name plate

2. Bolts

3. Valve housing

4. Spring washer

5. Spacer

6. O-ring seal

7. O-ring seal

8. Valve drive shaft

9. Channel plate

10. Disc valve

11. Balance plate

12. Guide pin

13. O-ring seal

14. Guide pin

15. Gearwheel set

16. Intermediate plate

17. O-ring seal

18. Conical seal ring

19. Cardan shaft

12

13

11

14

10

15

13

16

17

18

9

8

7

6

5

4

C1892

19

2

1

Fig. C1892 shows an exploded view of the hydraulic
torque motor. Before disassembling the torque motor,
clean the outer surface of all loose dirt and grease and dry
with compressed air. Be sure all openings are plugged to
prevent solvent or soap entering the torque motor.

3

WARNING

To avoid eye injury, use safety goggles when cleaning
with compressed air.

IMPORTANT

When making repairs to the hydraulic system, keep
the work area and parts clean. Use caps and plugs
on all open line and ports.

2-32

2

Parts Illustration

DRIVE MOTOR 2.12

Danfoss OMT FL Brake
Diagram C1893 Index

1. Bearing nut

2. Bearing, small

3. Screw

4. Bearing housing

5. O-ring seal

6. Spring

7. Spring

8. Piston

9. O-ring seal

10. Ring

11. O-ring seal

12. O-ring seal

13. Inner brake disc

14. Outer brake disc

15. Spacer disc

16. Bearing housing

17. Bearing

18. Splined shaft

19. O-ring seal

20. Shaft seal

21. Front cover

22. Dust seal ring

23. Screws

1

2

6

3

7

8

13

14

3

4

9

10

11

15

C1893

5

12

18

Fig. C1893 shows an exploded view of the hydraulic
torque motor brake. Before disassembling the torque
motor and or brake, clean the outer surface of all loose
dirt and grease and dry with compressed air. Be sure all
openings are plugged to prevent solvent or soap entering
the torque motor.

To avoid eye injury, use
safety goggles when clean ­ing with compressed air.

16

17

19

20

21

22

23

2-33

DRIVE MOTOR 2.12

Disassembly

1 Place the drive motor in a vise with the output shaft
facing down. Clamp the motor to the vise, holding it by
the mounting flange area. Do not clamp the motor on the
housing as excessive pressure will cause distortion.
2 Mark a line across the various sections of the drive
motor to assist in reassembly. (fig. C2287)

3 Remove the small allen head socket plug located
between two of the section bolts.( fig. C2288)

Mark sections

C2287

Remove restrictor plug

4 Insert an allen wrench into the open hole and remove
the set screw restrictor. (fig. C2289)

5 Remove the 4 bolts from the drive motor valve hous­ing. (fig. C2290) Upon reassembly, torque the bolts in a
criss cross pattern at 130 ~ 135 ft/lbs. (177 ~ 183.5 N.m.)

C2288

Remove restrictor

C2289

Remove section bolts

2-34

C2290

2

DRIVE MOTOR 2.12

Disassembly (cont’d)

6 Insert a small screwdriver into the mounting holes of
the valve housing assembly and remove the 2 shuttle
valve plugs, one each side. (fig. C2291, 2293)

Remove shuttle
valve plugs

C2291

Shuttle
valve plug

7 Insert a small screwdriver into the shuttle valve plug
hole and retrieve the springs. (fig. C2293) There is one on
either side.

8 Push out the shuttle valve poppet using the screw­driver. (fig. C2294)

C2292

Shuttle valve springs

C2293

Shuttle valve poppet

C2294

2-35

DRIVE MOTOR 2.12

Disassembly (cont’d)

9 Carefully lift the valve housing straight up. (fig.
C2295) Place your fingers under the valve housing to
hold the channel plate in place.

10 Remove the channel plate. (fig. C2296)

C2295

Channel plate

Disc valve

11 Remove the disc valve and balance plate from the
valve housing section. (fig. C2297, C2298)
12 Inspect the parts for wear and replace as required.
Replace all seals with new when assembling the drive
motor.

C2296

Locating pin

Notch

C2297

Channel plate

Disc valve

Valve housing

Balance plate

Spacer

Spring washers

2-36

C2298

2

DRIVE MOTOR 2.12

C2303

C2300

2-37

DRIVE MOTOR 2.12

Disassembly (cont’d)

15 Remove the cardan (drive) shaft (fig. C2304).
16 Remove the intermediate spacer (fig. C2305) .
Replace the seal with new item at time of assembly.

Cardan shaft (drive)

C2304

Intermediate spacer

17 A special tool will be required as shown in fig.
C2306 to remove the bearing nut (fig. C2307). Tool
shown was made using 1/2 in. X 1 in. X 3 in. long
(12mm x 25mm x 76mm L) material. Two holes were
drilled and tap 60mm apart, to accept 6mm X 30mm
machine screws.

C2305

Special tool

3 in.

(76mm)

6mm machine screws

2.4 in.

(60 mm)

C2306

Bearing nut

2-38

C2307

2

DRIVE MOTOR 2.12

Disassembly (cont’d)

18 Place the special tool on the bearing nut and remove
the bearing nut. (fig. C2308, C2309).

Special tool

C2308

Bearing nut

19 Remove the drive motor from the vise and remove
the screws retaining the front cover to the bearing hous­ing. (fig. C2310, C2311). Replace the seals with new at
time of assembly.

C2309

Retaining screws

C2310

Front cover

C2311

2-39

DRIVE MOTOR 2.12

Disassembly (cont’d) Output shaft and large bearing

20 Use a press and appropriate sized arbor to push the
output shaft from the bearings. (fig. C2312).

C2312

21 Remove the small bearing from the housing. (fig.
C2313). Inspect both bearings and races. Replace as
required.

22 Remove the bolts from the around the bearing hous­ing. (fig. C2314).

Small bearing

C2313

Bearing housing bolts

23 Separate the bearing housing sections. (fig. C2315) A
mallet may be required to assist removal.

2-40

C2314

Separate section

C2315

2

DRIVE MOTOR 2.12

Disassembly (cont’d)

24 Remove the bearing housing (fig. C2316).

25 Remove the brake springs from the brake piston. (fig.
C2317) There are inner and outer springs.

Bearing housing

Seal

C2316

Inner and outer spring

26 Remove the piston from the housing by pushing
through from the output shaft side. (fig. C2318)

27 Remove the brake disc assemblies. Note the positions
of the steel and fibre plates. (fig. C2319). Check the
plates for wear and replace as required.

C2317

Piston

Seals

C2318

C2319

2-41

DRIVE MOTOR 2.12

Assembly

1 Install the output shaft to the housing. (fig. C2321)

2 Install the front cover to the housing and torque the
screws to 12 Nm. (8.9 lbs / ft) (fig. C2322). Use new
seals when assembling the motor.

Output shaft and bearing

C2321

Front cover

3 Install the brake disc spacer ring to the housing. (fig.
C2320)

4 Install the brake disc plates. (fig. C2323, C2324,
C2319) Start with a fibre plate, add a steel plate, then
fibre and so on until the last plate to be installed is a fibre
plate.

NOTE:The fibre plates

IMPORTANT

are also called outer plates
due to the “teeth” outside
of the plate.

C2322

Spacer ring

C2320

Steel plate

Add fibre plate first

2-42

C2324

2

DRIVE MOTOR 2.12

Assembly

5 Continue adding plates, 12 fibre, 11 steel plates, to
the housing. (fig. C2323, C2319)

Add steel plate second

C2323

Brake discs

6 Install the piston to the housing, over the brake discs.
(fig. C2318) Use new seals when assembling the motor.
Align one of the piston spring pockets with the hydraulic
inlet port opening in the housing. (fig. C2316)

C2319

Piston

Seals

C2318

Bearing housing

Align spring to hydraulic port

Springs

C2316

2-43

DRIVE MOTOR 2.12

Assembly (cont’d)

7 Install the bearing housing bolts and torque to 46.5
lbs / ft. +/- 2 lbs / ft. (63 Nm +/- 3 Nm) (fig. C2314)

Housing bolts

C2314

8 Install the small bearing to the output shaft (fig.
C2313) in the following sequence:

a.Apply pressure, 12 bar (175 psi), to the brake ports

to release the brakes.

b. Press the bearing onto the output shaft with a force

of 350 daN (780 pounds of force), while rotating the
housing back and forth. Be sure to press only on the inner
race of the bearing.

c. Remove the brake release pressure before remov-

ing the force acting on the bearing.

d. Install the bearing nut and torque to 45 lbs / ft. (60

Nm) Strike the nut with blows from a mandrel and ham ­mer to prevent the nut from loosening.

Small bearing

C2313

Bearing nut

9 Install a new seals to the intermediate plate. (fig.
C2325). Apply petroleum jelly to the cup seal to retain in
position.

2-44

C2309

Seals

C2325