Danfoss H1T 045/053, H1T 060/068 Service guide
Service Manual
H1T 045/053, 060/068
Axial Piston Tandem Pumps
www.danfoss.com
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Revision history Table of revisions
Date Changed Rev
December 2021 Added HDC control 0501
September 2020 Changed document number from 'AX00000103' to 'AX152886481761' and added
important info about PL screens
November 2018 Major layout update. 0401
June 2018 Angle sensor topics added. 0303
August 2017 Minor update. 0302
May 2017 Added frames H1T 060/068 0301
Oct. 2007-March 2015 Various changes. AB-BD
Jun 2007 First edition. AA
0405
2 | © Danfoss | December 2021 AX152886481761en-000501
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Contents
Introduction
Hydrostatics Servicing Overview................................................................................................................................................ 5
General Servicing Instructions.....................................................................................................................................................5
Safety Precautions............................................................................................................................................................................6
Independent Braking System................................................................................................................................................. 6
High Inlet Vacuum...................................................................................................................................................................... 6
Manufacturer’s Warranty..........................................................................................................................................................6
The Basic Closed Circuit................................................................................................................................................................. 7
Case Drain and Heat Exchanger..................................................................................................................................................7
Tandem Pumps Design.................................................................................................................................................................. 8
H1T pumps pictorial diagram...................................................................................................................................................... 9
H1T Tandem Pumps Schematics..............................................................................................................................................10
System Schematic for Tandem Pumps...................................................................................................................................11
Operation
Pressure Limiter Valves................................................................................................................................................................ 12
Pressure Limiter Sectional View.......................................................................................................................................... 12
High Pressure Relief Valve (HPRV) and Charge Check Valve.......................................................................................... 13
HPRV/Charge Check Valve Sectional View...................................................................................................................... 13
Charge Pressure Relief Valve (CPRV)....................................................................................................................................... 15
Electrical Displacement Control (EDC)................................................................................................................................... 15
EDC Operation...........................................................................................................................................................................16
Hydraulic Displacement Control (HDC)................................................................................................................................. 17
HDC principle.............................................................................................................................................................................17
HDC operation...........................................................................................................................................................................17
Manual Override (MOR)............................................................................................................................................................... 19
Manual Displacement Control (MDC) ....................................................................................................................................19
MDC operation.......................................................................................................................................................................... 20
MDC Torque................................................................................................................................................................................21
Neutral start switch (NSS)...................................................................................................................................................... 21
Case Gauge Port M14..............................................................................................................................................................21
Control-Cut-Off (CCO) and Brake Release Valves............................................................................................................... 21
Operating Parameters
Input Speed......................................................................................................................................................................................24
Independent Braking System...............................................................................................................................................24
System Pressure..............................................................................................................................................................................24
Servo Pressure.................................................................................................................................................................................26
Charge Pressure..............................................................................................................................................................................26
Charge Pump Inlet Pressure.......................................................................................................................................................26
Case Pressure...................................................................................................................................................................................26
External Shaft Seal Pressure....................................................................................................................................................... 27
Temperature.................................................................................................................................................................................... 27
Viscosity.............................................................................................................................................................................................27
Technical Specifications
H1 Pumps General Specification..............................................................................................................................................28
Technical Data for H1 Tandem Pumps...................................................................................................................................28
Operating parameters for H1 Tandem Pumps....................................................................................................................29
Fluid Specification......................................................................................................................................................................... 30
Fluid and Filter Maintenance Recommendations
Pressure Measurements
Port locations and gauge installation - 045/053.................................................................................................................32
Port locations and gauge installation - 060/068.................................................................................................................33
Initial Startup Procedures
Start-Up Procedure........................................................................................................................................................................34
Troubleshooting
Safety Precautions......................................................................................................................................................................... 36
©
Danfoss | December 2021 AX152886481761en-000501 | 3
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Contents
High Inlet Vacuum....................................................................................................................................................................36
Unintended machine movement....................................................................................................................................... 36
Independent Braking System...............................................................................................................................................36
Manufacturer’s Warranty....................................................................................................................................................... 36
Electrical Troubleshooting..........................................................................................................................................................37
Integral Filter Bypass.....................................................................................................................................................................37
Neutral Difficult or Impossible to Find................................................................................................................................... 37
Transmission Operates Normally in One Direction Only.................................................................................................37
System Operating Hot..................................................................................................................................................................38
System Will Not Operate in Either Direction........................................................................................................................38
System Noise or Vibration...........................................................................................................................................................39
Sluggish System Response.........................................................................................................................................................39
Adjustments
Standard Procedures.................................................................................................................................................................... 40
Charge Pressure Relief Valve Adjustment.............................................................................................................................41
Pressure Limiter..............................................................................................................................................................................44
Pressure Limiter Screens........................................................................................................................................................ 44
Pressure Limiter Adjustment (060/068 only)..................................................................................................................44
Charge check / HPRV adjustment............................................................................................................................................ 47
Engaging the Bypass Function..................................................................................................................................................48
Displacement Limiter Adjustment for Tandem Pumps................................................................................................... 49
Control Neutral Adjustment.......................................................................................................................................................51
Mechanical Neutral Adjustment...............................................................................................................................................53
Pump setup.................................................................................................................................................................................53
Servo Adjustment for Tandem Pumps...................................................................................................................................54
Minor repair
Standard Procedures at Removing Pump.............................................................................................................................57
EDC/HDC Control Repair............................................................................................................................................................. 57
EDC/HDC Control Installation.............................................................................................................................................. 58
Control Solenoids Repair.............................................................................................................................................................59
MDC Control Repair.......................................................................................................................................................................60
MDC Control Assembly...........................................................................................................................................................61
Angle sensor on EDC Repair.......................................................................................................................................................62
EDC with Angle Sensor Repair...................................................................................................................................................63
Shaft, Seal and Bearing Repair...................................................................................................................................................65
Shaft, Seal and Bearing Installation....................................................................................................................................66
Charge Pump Repair (045/053 only).......................................................................................................................................67
Charge Pump Installation......................................................................................................................................................68
Charge Check and HPRV Repair (045/053)............................................................................................................................69
HPRV Port Relationship...........................................................................................................................................................70
HPRV (60/68)....................................................................................................................................................................................71
Pressure Limiter Screens........................................................................................................................................................ 71
HPRV Repair (060/068)............................................................................................................................................................71
Charge Pressure Relief Valve Repair........................................................................................................................................73
Control Cut-off Valve / Brake Valve Repair............................................................................................................................74
Torque Chart
Fasteners and Plugs...................................................................................................................................................................... 76
Fastener Size and Torque Chart................................................................................................................................................77
Plug Size and Torque Chart........................................................................................................................................................78
4 | © Danfoss | December 2021 AX152886481761en-000501
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
Hydrostatics Servicing Overview
This manual includes information on installation, maintenance, and minor repair of the . It includes a
description of the unit and its individual components, troubleshooting information, and minor repair
procedures.
Performing minor repairs may require the unit to be removed from the vehicle/machine. Thoroughly
clean the unit before beginning maintenance or repair activities. Since dirt and contamination are the
greatest enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This is
especially important when changing the system filter and when removing hoses or plumbing.
A worldwide network of Danfoss Global Service Partners is available for major repairs. Danfoss trains and
certifies Global Service Partners on a regular basis. You can locate your nearest Global Service Partner
using the distributor locator at http://www.danfoss.com.
For detailed technical information about the , please see the relevant technical information document.
Attention
Major repairs requiring the removal of a unit’s center section, servo sleeves, or front flange voids the
warranty unless a Danfoss Authorized Service Center performs them.
General Servicing Instructions
Follow these general procedures when repairing this product:
Icon Description Instructions
If necessary, remove the unit from the vehicle/machine.
•
Chock the wheels on the vehicle or lock the mechanism to inhibit movement.
•
Remove the unit
Keep it clean
Replace O-ring,
gasket
Secure the unit
Be aware that hydraulic fluid may be under high pressure and/or hot.
•
Inspect the outside of the pump and fittings for damage.
•
Cap hoses after removal to prevent contamination.
•
Cleanliness is a primary means of assuring satisfactory pump life, on either
•
new or repaired units.
Clean the outside of the pump thoroughly before disassembly.
•
Take care to avoid contamination of the system ports.
•
Cleaning parts by using a clean solvent wash and air drying is usually
•
adequate.
As with any precision equipment, keep all parts free of foreign materials and
•
chemicals.
Protect all exposed sealing surfaces and open cavities from damage and
•
foreign material.
If left unattended, cover the pump with a protective layer of plastic.
•
Danfoss recommends that you replace all O-rings, seals and gaskets.
•
Lightly lubricate all O-rings with clean petroleum jelly prior to assembly.
•
For repair, place the unit in a stable position with the shaft pointing
•
downward.
It will be necessary to secure the pump while removing and torquing end
•
covers, controls, and valves.
©
Danfoss | December 2021 AX152886481761en-000501 | 5
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
Safety Precautions
Always consider safety precautions before beginning a service procedure. Protect yourself and others
from injury. Take the following general precautions whenever servicing a hydraulic system.
Unintended machine movement
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
Secure the machine or disable/disconnect the mechanism while servicing to protect against unintended
movement.
Independent Braking System
Unintended vehicle or machine movement hazard. Exceeding maximum speed may cause a loss of
hydrostatic drive line power and braking capacity.
Machine manufacturer is responsible to provide a braking system, redundant to the hydrostatic
transmission, sufficient to stop and hold the vehicle or machine in the event of hydrostatic drive power
loss. The braking system must also be sufficient to hold the machine in place when full power is applied.
High Inlet Vacuum
High inlet vacuum causes cavitation which can damage internal pump components.
Manufacturer’s Warranty
Contamination can damage internal components and void the manufacturer’s warranty.
Take precautions to ensure system cleanliness when removing and installing system lines.
Fluid Under Pressure
Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious
injury and/or infection. This fluid may also be hot enough to cause burns.
Relieve pressure in the system before removing hoses, fittings, gauges, or components. Never use your
hand or any other body part to check for leaks in a pressurized line. Use caution when dealing with
hydraulic fluid under pressure. Seek medical attention immediately if you are cut by hydraulic fluid.
Flammable cleaning solvents
Some cleaning solvents are flammable.
Do not use cleaning solvents in an area where a source of ignition may be present to avoid possible fire.
Personal safety
Protect yourself from injury whenever servicing a hydraulic system.
Use proper safety equipment, including safety glasses, at all times.
Hazardous material
Hydraulic fluid contains hazardous material.
Avoid prolonged contact with hydraulic fluid. Always dispose of used hydraulic fluid according to state,
and federal environmental regulations.
6 | © Danfoss | December 2021 AX152886481761en-000501
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
The Basic Closed Circuit
Hydraulic lines connect the main ports of the pump to the main ports of the motor. Fluid flows in either
direction from the pump to the motor and back. Either of the hydraulic lines can be under high pressure.
In pumping mode the position of the pump swashplate determines which line is high pressure as well as
the direction of fluid flow.
Case Drain and Heat Exchanger
The pump and motor require case drain lines to remove hot fluid from the system. The pump and motor
drain from the topmost port to ensure the cases remain full of fluid.
The motor case drain can connect to the lower drain port on the pump housing or it can tee into the case
drain line upstream of the heat exchanger. A heat exchanger with bypass valve cools the case drain fluid
before it returns to the reservoir.
©
Danfoss | December 2021 AX152886481761en-000501 | 7
P106 146E
Slipper
Piston
Cylinder block
Swashplat e
Rear shaft
Electric displacement control
Servo piston
Valve plates
Shaft coupling
Swashplate feedback pin
Front sha ft
Electric displacement control
Servo piston
Swashplate feedback pin
Piston
Slipper
Shaft seal
Swashplat e
Cylinder block
Swashplate bearing
Swashplate bearing
Front shaft bearing
Center shaft bearings
Rear shaft bearing
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
Tandem Pumps Design
Danfoss H1 tandem closed circuit piston pumps convert input torque to hydraulic power. The tandem
design powers two independent drive trains for dual-path propel applications.
The two-piece input shaft transmits rotational force to the cylinder block. A splined coupling connects
the front and rear shafts. Bearings at the front, rear, and center of the pump support the shaft. Splines
connect each shaft to a cylinder block. A lip-seal at the front end of the pump prevents leakage where the
shaft exits the pump housing. The spinning cylinder block contains nine reciprocating pistons. Each
piston has a brass slipper connected at one end by a ball joint. The block spring, ball guide, and slipper
retainer hold the slippers to the swashplate. The reciprocating movement of the pistons occurs as the
slippers slide against the inclined swashplates during rotation.
Via the valve plates, one half of each cylinder block is connected to port A or C and the other half to port
B or D. Front and rear sections have independent porting in the center section. As each piston cycles in
and out of its bore, fluid is drawn from one port and displaced to the other thereby imparting hydraulic
power into the system. A small amount of fluid is allowed to flow from the cylinder block/valve plate and
slipper/swashplate interfaces for lubrication and cooling. Case drain ports return this fluid to the
reservoir. An external charge pump (not shown) provides clean, cool fluid to makeup this lubricating flow
and to maintain minimum loop pressure.
The angle of each swashplate controls the volume and direction of fluid displaced into the system. The
servo pistons control the angle of the swashplates. Each pump control, by varying the pressure at the
servo pistons, controls each piston’s position. An electric signal to the control coils transmits the
command from the operator to the pump. Mechanical feedback of the swashplate position to the control
through the feedback pins allows for very precise displacement control and increases overall system
stability. Non-feedback control options do not use the mechanical feedback link.
Cross section view
8 | © Danfoss | December 2021 AX152886481761en-000501
Servo Control
Cylinder
Displacement Control
Servo Control
Cylinder
Displacement Control
Reservoir
Suction
Screen
Filter
Bypass check
Heat exchanger
To Pump
Case
To Pump
Case
Variable
Displacement
Pump
Input
Shaft
Pump Swashplate
Charge Pump
Pump Swashplate
Charge
Pressure
Relief
Valve
Charge check /
HPRV valve
Control
Cutoff
Valve
System Pressure
Servo Pressure
Low Loop Pressure
Suction/Case Drain/
System Return
Charge Pressure
Cylinder
block
assembl y
Motor
swashplat e
Output
shaft
Motor
servo
piston
P106147
Loop
Flushing
Valve
To
Motor
Case
Motor
servo
piston
Motor
swashplate
Output
shaft
Cylinder
block
assembly
Displacement
limiter
Loop
Flushing
Valve
Motor
displacement
control valve
Motor
displacement
control valve
To
Motor
Case
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
H1T pumps pictorial diagram
©
Danfoss | December 2021 AX152886481761en-000501 | 9
P106 148E
M4
M5
M5
M4
M3
L3
MBMC
MA
MD
C
D
B
A
E
X7
C1
C2
C1
C2
CW
CW
Flow
out C
Flow
out A
M5
M4
A
MA
MD
D
B MB
MC
C
M5
M4
H1 Tandem
E
M3
ccw
flow out B flow out D
C1 C2
M14
C1C2
M14
1
2
Supply/Ground
CONTROL SOLENOID C1
Ground/Supply
1
2
Supply/Ground
Ground/Supply
CONTROL SOLENOID C2
1
2
Supply/Ground
CONTROL SOLENOID C2
Ground/Supply
1
2
Supply/Ground
Ground/Supply
CONTROL SOLENOID C1
X7
1
2
Supply/Ground
Ground/Supply
CCO SOLENOID
1
2
Supply/Ground
Ground/Supply
BRAKE SOLENOID
L1
L3
P109541
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
H1T Tandem Pumps Schematics
The schematics below show the function of an H1 tandem axial piston variable displacement pump with
electric displacement control (EDC) and optional control cut-off valve.
045/053 Tandem
060/068 Tandem
10 | © Danfoss | December 2021 AX152886481761en-000501
C1
C1
C2C2
M14
M14
CW
F00B
F00A
F00B F00A
A
B
MA
E
C D
MD
MB
M3
L3
MC
M4
M5
M4
M5
PTO
X7
P003 207E
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Introduction
System Schematic for Tandem Pumps
The schematic below shows the function of H1T axial piston variable displacement tandem pumps with
electric displacement control (EDC).
System schematic, tandem pumps
©
Danfoss | December 2021 AX152886481761en-000501 | 11
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Pressure Limiter Valves
Pressure limiter valves provide system pressure protection by compensating the pump swash plate
position when the set pressure of the valve is reached. A pressure limiter is a non-dissipative (non heat
generating) pressure regulating system.
Each side of the transmission loop has a dedicated pressure limiter valve that is set independently. A
pump configured with pressure limiter must have pressure limiters on both sides of the system pressure
loop. The pump order code allows for different pressure settings to be used at each system port.
The pressure limiter setting is the maximum differential pressure between the high and low loops. When
the pressure limiter setting is reached, the valve ports oil to the low-pressure side of the servo piston. The
change in servo differential pressure rapidly reduces pump displacement. Fluid flow from the valve
continues until the resulting drop in pump displacement causes system pressure to fall below the
pressure limiter setting.
An active pressure limiter destrokes a pump to near neutral when the load is in a stalled condition. The
pump swash-plate moves in either direction necessary to regulate the system pressure, including into
stroke (overrunning) or over-center (winch payout).
The pressure limiter is optional on H1 pumps (except H1T 045/053 tandem pumps).
Pressure Limiter Sectional View
12 | © Danfoss | December 2021 AX152886481761en-000501
P003 268
P003 269
P109187
1
2
P109188
1
2
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
High Pressure Relief Valve (HPRV) and Charge Check Valve
All H1 pumps have a combination high pressure relief and charge check valve. The high pressure relief
function is a dissipative (heat generating) pressure control valve for the purpose of limiting excessive
system pressures. The charge check function replenishes the low pressure side of the working loop with
charge oil.
Each side of the transmission loop has a dedicated HPRV valve that is non-adjustable with a factory set
pressure. When system pressure exceeds the factory setting of the valve, oil is passed from the high
pressure system loop, into the charge gallery, and into the low pressure system loop via the charge
check.
The pump may have different pressure settings to be used at each system port. When an HPRV valve is
used in conjunction with a pressure limiter, the HPRV valve is always factory set above the setting of the
pressure limiter. The system pressure shown in the order code for pumps with only HPRV is the HPRV
setting.
The system pressure shown in the order code for pumps with pressure limiter and HPRV is a reflection of
the pressure limiter setting:
HPRVs are set at low flow condition. Any application or operating condition which leads to elevated HPRV
flow will cause a pressure rise with flow above the valve setting. Consult factory for application review.
Excessive operation of the HPRV will generate heat in the closed loop and may cause damage to the
internal components of the pump.
HPRV/Charge Check Valve Sectional View
HPRV and Charge Check Valve with Bypass Function (except 045/053)
Relief mode
Charging mode
HPRV and Charge Check Valve with Bypass Function (except H1P 045/053)
Charging mode
Relief mode
©
Danfoss | December 2021 AX152886481761en-000501 | 13
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
1. Low pressure side of working loop
2. Charge check and HPRV
1. High pressure side of working loop
2. Charge check and HPRV
14 | © Danfoss | December 2021 AX152886481761en-000501
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Charge Pressure Relief Valve (CPRV)
The charge pressure relief valve is a direct acting poppet valve that opens and discharges fluid to the
pump case when pressure exceeds a designated level. The charge pressure relief valve maintains charge
pressure at a designated level above case pressure.
This level is nominally set with the pump running at 1800 min-1(rpm), and with a fluid viscosity of 32
mm²/s [150 SUS]. In forward or reverse, charge pressure will be slightly lower than in neutral position. The
model code of the pump specifies the charge pressure relief valve setting. Typical charge pressure
increase from 1.2-1.5 bar per 10 l/min [17.4-21.8 psi per 2.64 US gal/min]. For external charge flow the
CPRV is set according to the table below:
Standard level setting is ∆p = 21 ± 1.1 bar [304 ± 16 psi] with the pump running at 1500 min-1(rpm) and
flow = 23.80 - 29.5 l/min [ 6.3 - 7.8 US gal/min]. Typical charge pressure increase is 2 bar per 10 l/min [29
psi per 2.64 US gal/min].
CPRV flow setting for external charge supply
Tandem 045/053 Single 045/053 Single 060—165 Single 210/250/280
30 l/min [7.9 US gal/min] 15 l/min [3.9 US gal/min] 22.7 l/min [6.0 US gal/min] 40.0 l/min [10.6 US gal/min]
Charge pressure relief valve
Electrical Displacement Control (EDC)
An EDC is a displacement (flow) control. Pump swash plate position is proportional to the input
command and therefore vehicle or load speed (excluding influence of efficiency), is dependent only on
the prime mover speed or motor displacement.
The Electrical Displacement Control (EDC) consists of a pair of proportional solenoids on each side of a
three-position, four-way porting spool. The proportional solenoid applies a force input to the spool,
which ports hydraulic pressure to either side of a double acting servo piston. Differential pressure across
the servo piston rotates the swash plate, changing the pump‘s displacement from full displacement in
one direction to full displacement in the opposite direction.
A serviceable 170 μm screen is located in the supply line immediately before the control porting spool.
Under some circumstances, such as contamination, the control spool could stick and cause the pump to
stay at some displacement.
©
Danfoss | December 2021 AX152886481761en-000501 | 15
P003 191
Feedback from
Swash plate
PTF00B
M14
C1 C2
F00A
P003 478E
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Electrical Displacement Control
EDC schematic, feedback from swash plate
EDC Operation
H1 EDC’s are current driven controls requiring a Pulse Width Modulated (PWM) signal. Pulse width
modulation allows more precise control of current to the solenoids.
The PWM signal causes the solenoid pin to push against the porting spool, which pressurizes one end of
the servo piston, while draining the other. Pressure differential across the servo piston moves the
swashplate.
A swashplate feedback link, opposing control links, and a linear spring provide swashplate position force
feedback to the solenoid. The control system reaches equilibrium when the position of the swashplate
spring feedback force exactly balances the input command solenoid force from the operator. As
hydraulic pressures in the operating loop change with load, the control assembly and servo/swashplate
system work constantly to maintain the commanded position of the swashplate.
The EDC incorporates a positive neutral deadband as a result of the control spool porting, preloads from
the servo piston assembly, and the linear control spring. Once the neutral threshold current is reached,
the swashplate is positioned directly proportional to the control current. To minimize the effect of the
control neutral deadband, we recommend the transmission controller or operator input device
incorporate a jump up current to offset a portion of the neutral deadband.
The neutral position of the control spool does provide a positive preload pressure to each end of the
servo piston assembly.
When the control input signal is either lost or removed, or if there is a loss of charge pressure, the springloaded servo piston will automatically return the pump to the neutral position.
16 | © Danfoss | December 2021 AX152886481761en-000501
P400520
P400519
X1
F00B
F00A
Feedback from
Swashplate
T P
X2M14
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Hydraulic Displacement Control (HDC)
HDC principle
An HDC is a Hydraulic Displacement Control. Pump swashplate position is proportional to the input
command and therefore vehicle speed or load speed (excluding influence of efficiency), is dependent
only on the prime mover speed or motor displacement.
The HDC control uses a hydraulic input signal to operate a porting spool, which ports hydraulic pressure
to either side of a double acting servo piston. The hydraulic signal applies a force input to the spool
which ports hydraulic pressure to either side of a double acting servo piston. Differential pressure across
the servo piston rotates the swashplate, changing the pump’s displacement from full displacement in
one direction to full displacement in the opposite direction. Under some circumstances, such as
contamination, the porting spool could stick and cause the pump to stay at some displacement.
A serviceable 175 μm screen is located in the supply line immediately before the control porting spool.
HDC control
HDC schematic
HDC operation
HDC’s are hydraulically driven control which ports hydraulic pressure to either side of a porting spool,
which pressurizes one end of the servo piston, while draining the other end to case. Pressure differential
across the servo piston moves the swashplate.
A swashplate feedback link, opposing control linkage, and a linear spring provide swashplate position
force feedback to the hydraulic pressure. As hydraulic pressures in the operating loop change with load,
the control assembly and servo/swashplate system work constantly to maintain the commanded position
of the swashplate.
©
Danfoss | December 2021 AX152886481761en-000501 | 17
"0"
Signal pressure
Displacement
100 %
a b
-b -a
100 %
P102 031E
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
The HDC incorporates a positive neutral dead band as a result of the control spool porting, preloads from
the servo piston assembly, and the linear control spring. Once the neutral threshold point is reached, the
swashplate is positioned directly proportional to the control pressure.
When the control input is either lost or removed, or if there is a loss of charge pressure, the spring loaded
servo piston will automatically return the pump to the neutral position.
Pump displacement vs signal pressure
18 | © Danfoss | December 2021 AX152886481761en-000501
P003 204
PTF00B
M14
C2
C1
F00A
W
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Manual Override (MOR)
All controls are available with a manual override functionality, either as a standard or as an option for
temporary actuation of the control to aid in diagnostics.
Control with manual override
MOR schematic (EDC control shown)
Feedback from swash plate.
The MOR plunger has a 4 mm diameter and must be manually depressed to be engaged. Depressing the
plunger mechanically moves the control spool which allows the pump to go on stroke. The MOR should
be engaged anticipating a full stroke response from the pump.
An o-ring seal is used to seal the MOR plunger where initial actuation of the function will require a force
of 45 N to engage the plunger. Additional actuation typically require less force to engage the MOR
plunger.
Proportional control of the pump using the MOR should not be expected.
Warning
Unintended MOR operation will cause the pump to go into stroke; example: vehicle lifted off the ground.
The vehicle or device must always be in a safe condition when using the MOR function.
Refer to control flow table for the relationship of solenoid to direction of flow.
Manual Displacement Control (MDC)
A Manual proportional Displacement Control (MDC) consists of a handle on top of a rotary input shaft.
The shaft provides an eccentric connection to a feedback link. This link is connected on its one end with a
porting spool. On its other end the link is connected the pumps swashplate.
This design provides a travel feedback without spring. When turning the shaft the spool moves thus
providing hydraulic pressure to either side of a double acting servo piston of the pump.
Differential pressure across the servo piston rotates the swash plate, changing the pump’s displacement.
Simultaneously the swashplate movement is fed back to the control spool providing proportionality
between shaft rotation on the control and swash-plate rotation. The MDC changes the pump
displacement between no flow and full flow into opposite directions.
©
Danfoss | December 2021 AX152886481761en-000501 | 19
"0"
Lever rotation
"A"
Displacement
100 %
a
-a
100 %
"B"
-b
-d
b
c
d
-c
P301 752
C
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Under some circumstances, such as contamination, the control spool could stick and cause the pump to
stay at some displacement.
For the MDC with CCO option the brake port (X7) provides charge pressure when the coil is energized to
activate static function such as a brake release. The X7 port must not be used for any continuous oil
consumption.
The MDC is sealed by means of a static O-ring between the actuation system and the control block. Its
shaft is sealed by means of a special O-ring which is applied for low friction. The special O-ring is
protected from dust, water and aggressive liquids or gases by means of a special lip seal.
Manual Displacement Control Pump displacement vs. control lever rotation
Deadband on B side: a = 3° ±1°
Maximum pump stroke: b = 30° +2/-1°
Required customer end stop: c = 36° ±3°
Internal end stop: d = 40°
MDC operation
The MDC provides a mechanical dead-band required to overcome the tolerances in the mechanical
actuation. The MDC contains an internal end stop to prevent turning the handle into any inappropriate
position.
The MDC provides a permanent restoring moment appropriate for turning the MDC input shaft back to
neutral position only. This is required to take the backlash out of the mechanical connections between
the Bowden cable and the control.
High case pressure may cause excessive wear and the NSS to indicate that the control is not in neutral
position. In addition, if the case pressure exceeds 5 bar there is a risk of an insufficient restoring moment.
The MDC is designed for a maximum case pressure of 5 bar and a rated case pressure of 3 bar.
Customers must install some support to limit the setting range of their Bowden cable to avoid an
•
overload of the MDC.
Customers can apply their own handle design but they must care about a robust clamping
•
connection between their handle and the control shaft and avoid overload of the shaft.
Customers can connect two MDC’s on a tandem unit in such a way that the actuation force will be
•
transferred from the pilot control to the second control. The kinematic of the linkages must ensure
that either control shaft is protected from torque overload.
Caution
Using the internal spring force on the input shaft is not an appropriate way to return the customer
connection linkage to neutral, or to force a Bowden cable or a joystick back to neutral position. It is not
applicable for any limitation of the Bowden cable stroke, except the applied torque to the shaft will never
exceed 20 N•m.
20 | © Danfoss | December 2021 AX152886481761en-000501
C
P005 702
M14
M5
M4
M3
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
MDC Torque
Description Value
Torque required to move handle to maximum displacement 1.4 N•m [12.39 lbf•in ]
Torque required to hold handle at given displacement 0.6 N•m [5.31 lbf•in]
Maximum allowable input torque 20 N•m [177 lbf•in]
Caution
Volumetric efficiencies of the system will have impacts on the start and end input commands.
Neutral start switch (NSS)
The Neutral Start Switch (NSS) contains an electrical switch that provides a signal of whether the control
is in neutral. The signal in neutral is Normally Closed (NC).
Neutral start switch schematic
Neutral start switch data
Max. continuous current with switching
Max. continuous current without switching
Max. voltage
Electrical protection class
8.4 A
20 A
36 V
DC
IP67 / IP69K with mating connector
Case Gauge Port M14
The drain port should be used when the control is mounted on the unit’s bottom side to flush residual
contamination out of the control.
Control-Cut-Off (CCO) and Brake Release Valves
The H1 tandem pumps offer an optional Control-Cut-Off valve integrated into the pump center section
and a separate brake release valve allowing the controls to be activated before activating any auxiliary
functions.
The CCO valve shunts charge pressure from the pump controls allowing the servo springs to de-stroke
both pumps. The valve is normally open for fail-safe operation. The solenoid must be energized for the
pump to operate. When the machine control circuits energize the CCO solenoid, it connects charge
supply from the charge gallery to the pump controls.
©
Danfoss | December 2021 AX152886481761en-000501 | 21
P106 148E
M4
M5
M5
M4
M3
L3
MBMC
MA
MD
C
D
B
A
E
X7
C1
C2
C1
C2
CW
CW
Flow
out C
Flow
out A
M5
M4
A
MA
MD
D
B MB
MC
C
M5
M4
H1 Tandem
E
M3
ccw
flow out B flow out D
C1 C2
M14
C1C2
M14
1
2
Supply/Ground
CONTROL SOLENOID C1
Ground/Supply
1
2
Supply/Ground
Ground/Supply
CONTROL SOLENOID C2
1
2
Supply/Ground
CONTROL SOLENOID C2
Ground/Supply
1
2
Supply/Ground
Ground/Supply
CONTROL SOLENOID C1
X7
1
2
Supply/Ground
Ground/Supply
CCO SOLENOID
1
2
Supply/Ground
Ground/Supply
BRAKE SOLENOID
L1
L3
P109541
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
The 045/053 tandem also supplies charge pressure to the port X7 for auxiliary operation of devices such
as spring applied/pressure released brakes. The control cut off valve also shunts pressure away from port
X7.
The 060/068 tandem offers a separate brake release valve that operates independently of the CCO valve
allowing the controls to be activated before activating any auxiliary functions. When the 60/68 brake
valve is deactivated the X7 port shunts to case.
045/053 Tandem
060/068 Tandem
22 | © Danfoss | December 2021 AX152886481761en-000501
1 2
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operation
Solenoid data
Description 12 V 24 V
Minimum supply voltage
Maximum supply voltage (continuous)
IP Rating IEC 60 529
DIN 40 050, part 9
Pin connector
For additional information, please contact Danfoss.
9 V
DC
16 V
DC
IP 67
IP 69K with mating connector
any order
18 V
32 V
DC
DC
©
Danfoss | December 2021 AX152886481761en-000501 | 23
W
Service Manual
H1T 045/053, 060/068 Axial Piston Tandem Pumps
Operating Parameters
Input Speed
Minimum
speed
Rated speed is the highest input speed recommended at full power condition. Operating at or
Maximum
speed
During hydraulic braking and downhill conditions, the prime mover must be capable of providing
sufficient braking torque in order to avoid pump over speed. This is especially important to consider for
turbo-charged and Tier 4 engines.
For more information please see Pressure and Speed Limits, BC152886484313, when determining speed
limits for a particular application.
Independent Braking System
is the lowest input speed recommended during engine idle condition. Operating below
minimum speed limits the pump’s ability to maintain adequate flow for lubrication and
power transmission.
below this speed should yield satisfactory product life.
Operating conditions between rated and maximum speed should be restricted to less
than full power and to limited periods of time.
is the highest operating speed permitted. Exceeding maximum speed reduces product
life and can cause loss of hydrostatic power and braking capacity. For most drive
systems, maximum unit speed occurs during downhill braking or negative power
conditions.
Warning
Never exceed the maximum speed limit under any operating conditions.
System Pressure
Unintended vehicle or machine movement hazard. Exceeding maximum speed may cause a loss of
hydrostatic drive line power and braking capacity.
Machine manufacturer is responsible to provide a braking system, redundant to the hydrostatic
transmission, sufficient to stop and hold the vehicle or machine in the event of hydrostatic drive power
loss. The braking system must also be sufficient to hold the machine in place when full power is applied.
Hydraulic unit life depends on the speed and normal operating — or weighted average — pressure that
can only be determined from a duty cycle analysis.
System pressure is the differential pressure between high pressure system ports. It is the dominant
operating variable affecting hydraulic unit life. High system pressure, which results
from high load, reduces expected life.
Application
pressure
Maximum
working
pressure
is the high pressure relief or pressure limiter setting normally defined within the
order code of the pump. This is the applied system pressure at which the drive line
generates the maximum calculated pull or torque in the application.
is the highest recommended application pressure and is not intended to be a
continuous pressure. Propel systems with application pressures at, or below this
pressure should yield satisfactory unit life given proper component sizing.
Application pressures above maximum working pressure will only be considered
with duty cycle analysis and factory approval.
Pressure spikes are normal and must be considered when reviewing maximum
working pressure.
24 | © Danfoss | December 2021 AX152886481761en-000501
Loading...