Continental Hydraulics HPV-6, HPV-10, HPV-15, HPV-20, HPV-29 Service Manual

CAUTION – Before performing any service

operation on any pump, be sure that all
pressure has been relieved from the system.

CAUTION – Before performing any service
operation on any pump, disconnect or lock
off power supply.

CAUTION – Before starting any pump, be
sure that any resulting machine function will
not endanger persons or equipment.

PRODUCT IDENTIFICATION

Each HPV Piston Pump has a Model Code stamped
on its escutcheon plate. See Figure 1 for the location
of the Model Code.

Date

Code

Model

Code

Figure 1

This Service Booklet applies to products with Model
Codes like the sample in Figure 2.

Basic Pump
Rotation

Seal Type
Ports

HPV - 6B35-RF-O-1R

Figure 2

SERVICE MANUAL

HPV Axial Piston Pumps

“B” Design Series

GENERAL SPECIFICATIONS

MOUNTING

Any unrestricted mounting position acceptable.
Horizontal mounting preferred. The mounting hub
and two-bolt mounting flange conform to SAE
mounting standards.

Continental Hydraulics does not recommend direct
rigid connection of piston pumps to the Prime Mover.
Use of a flexible coupling, a coupling that allows for
minor misalignment is recommended.

If the shaft connection to the Prime Mover is rigid, the
mounting face diametric concentricity and squareness
must be within .001 inch (0.03 mm) T.I.R. for a flange
mounted pump.

The HPV Piston Pump is designed for in-line drive.
Angle drive creates side loads on the shaft, and is not
acceptable.

SHAFT INFORMATION
Splined:

The coupling interface must be lubricated.
Continental Hydraulics recommends lithium
molydisulfate, or similar grease. The female coupling
should be hardened to 27-45 Rc, and must conform
to ANSI B92.1 Class 5 Fillet or Flat Root Side Fit.

Keyed:

High strength heat treated keys must be used.
Replacement keys must be hardened to 27-34 Rc.
Key corners must be chamfered .030 - .040 inch (.75

- 1.0 mm) at 45° to clear radii in the keyway.

PLUMBING

Connect inlet and outlet lines to the pump’s cover.
HPV fluid connections are SAE straight thread, SAE
flange or BSPP.

MODEL REAR PORT SIDE PORT

HPV-6 SAE-12 or 3/4” BSPP SAE-16 or 1” BSPP
HPV-10 SAE-20 or 1-1/4” BSPP SAE-20 or 1-1/4” BSPP
HPV-15 SAE-20 or 1-1/4” BSPP SAE-20 or 1-1/4” BSPP
HPV-20 SAE-20 or 1-1/4” BSPP SAE1-1/4” Flange*
HPV-29 SAE-20 or 1-1/4” BSPP SAE1-1/2” Flange**

* Per Code 62 ** Per Code 61

Maximum case pressure is 10 psi (0.70 bar). Case
pressure must never exceed inlet pressure by more
than 15 psi (1.0 bar). To prevent fluid drain-down
from the pump when idle, make certain that case
drain plumbing passes above the highest point of the
pump before entering the reservoir. Or, install a 5 psi
(.3 bar) case pressure check valve to assure that the
pump is always filled with hydraulic fluid.

The case drain line must be big enough to prevent
back pressure in excess of 10 psi (0.70 bar).

Form No. R92.00 Rev. 10/03

1

PLUMBING (continued...)
Hydraulic fluid from the case drain line should be

returned to the reservoir below the fluid level, and as
far from the supply intake as possible. All fluid lines
(whether pipe, tubing or hose) must be of adequate
size and strength to assure free flow through the
pump. Do not tee return lines together.

SYSTEM RELIEF VALVES

Although HPV series pumps have a very fast off­stroke compensator response, fast acting relief valves
are recommended in all cases for safety. They also
help reduce transient pressure spikes.

RECOMMENDED FLUID

Note: The following fluid recommendations

and specifications apply to HPV series
pumps only. Assure that all other
components in the hydraulic system have
compatible requirements.

Petroleum-based, and most phosphate esters. Fluids
should be designated by the manufacturer for use in
hydraulic systems. Fluids should be formulated with
oxidation inhibitors, anti-rust, anti-foam and
deaerating agents. Other fluids may be acceptable,
but special O-rings may be required. Nitrile (Buna)
seals are standard.

VISCOSITY

Maximum at full power . . . . . . .750 SUS (160 Cst)

Optimum for maximum life . . . .140 SUS (30 Cst)

Minimum at full power . . . . . . . 60 SUS (10 Cst)

VISCOSITY INDEX

90 V.I. minimum. Higher values extend the operating
temperature range, but may reduce fluid service life.

Fluid Operating Temperature – Operating
temperature should be determined by the viscosity
characteristics of the fluid used. Fluid temperature in
the reservoir during operation should be kept between
100° F. and 130° F. (38° C. and 54° C.) Because high
temperature degrades seals, reduces service life and
creates hazards, fluid temperature should not exceed
180° F. (82° C.) at the case drain.

CAUTION – Fluid temperatures in excess of
120° F. (49° C.) can cause serious burns and
scalding. Allow fluid to cool before
performing any repairs or maintenance.

Fluid Cleanliness – Control particle contamination by
changing or cleaning all filter elements periodically
BEFORE they become clogged and start to by-pass.
Fluid must be cleaned before and continuously during
operation to a cleanliness level of ISO 18/16/13 or
better. This level of cleanliness can usually be
accomplished by use of 10 micron filters. Better fluid
cleanliness will significantly extend component life.
Since contaminant generation varies with each
application, each must be analyzed to determine
proper filtration to maintain required cleanliness.

After Extended Shutdowns – Some types of
hydraulic fluids become tacky after long periods of
non-use. If possible, hand turn the pump several
times after extended shutdowns to assure that all
components move freely before powering up.

CAUTION – Before hand turning any pump,
be sure that any resulting machine function
will not endanger persons or equipment.

PREVENTIVE MAINTENANCE

This pump is self-lubricating. Preventive maintenance
is limited to keeping the system fluid clean by
changing filters regularly. Since filtering needs can
vary depending on applications, filters used with this
pump should be equipped with indicators that show
when changes are needed. Do not operate the pump
in a system with clogged or bypassing filters.

Keep all fittings and screws tight. Do not operate this
pump at pressures or speeds in excess of stated
limits. If the pump does not operate properly, check
the Trouble Shooting Section of this manual before
attempting to overhaul the pump.

Overhauls are relatively simple, and are covered in
the Repair Procedures Section of this manual.

Note: It is especially important to keep
suction or inlet piping and fittings tight
and in good repair. Air drawn into the
system through loose or damaged intake
fittings can cause the pump to fail.

START UP PROCEDURE FOR NEW INSTALLATION

1. Read and understand the Service Manual. Identify
components and their
functions.

2. Visually inspect system

Case Drain

Ports

components and lines for
possible damage.

3. Check reservoir for
cleanliness. Drain and
clean as required.

4. Check reservoir fluid
level and fill as required
with filtered fluid that

Figure 3

meets or exceeds ISO 18/16/13 cleanliness level. Fill
pump through either Case Drain Port (Figure 3).

5. Check drive alignment.

6. Check and activate oil cooler (if included in circuit).
Check fluid temperature.

7. Reduce relief valve pressure settings. Make sure
accurate pressure readings can be made at
appropriate places.

8. If the system includes solenoids, check for proper
actuation.

9. Jog electric motor to confirm proper rotation.
Jogging the electric motor primes the pump and
bleeds air from the system.

10. Start pump drive. Look for leaks, and listen for
excessive noise at the pump. If leaks, chattering or
other noises are observed, immediately turn the pump
off. Corrective actions are covered in the Trouble
Shooting Section.

11. Cycle unloaded machine at low pressure, and
observe actuation (at low speed, if possible).

12. Increase pressure settings gradually. Check for
leaks in all lines, especially in the pump inlet line.

13. Adjust system pressure as needed.

14. Gradually increase system speed to normal
operating level. Be alert for trouble as indicated by
noise, sound changes, system shocks, leaks, or air
bubbles in the reservoir.

2

Form No. R92.00 Rev. 10/03

START UP PROCEDURE (continued...)

15. When the system is running normally, check fluid
level and temperature at the reservoir. Repeat these
checks periodically. Excessive fluid temperatures will
damage the pump. If fluid temperature does not
stabilize at 140° F (60° C.) or less, stop the system
and take appropriate corrective action.

16. System is operational. Follow appropriate
maintenance procedures to assure fluid cleanliness
and proper operating temperature.

REPLACEMENT PUMP INSTALLATION

To prevent premature pump failure, make
sure that the entire hydraulic circuit is
flushed completely clean before
installing and operating a replacement
pump.

Simply draining the reservoir or relying on the
system’s filters is not enough to adequately clean the
fluid. Debris trapped in other components or lines
may damage the components themselves, or be
drawn into the pump. Failure to properly flush the
system before installing a replacement pump voids
the pump’s warranty.

The following procedures checklist will help you
replace a hydraulic pump with confidence that it will
provide satisfactory pump life.

1. Determine the cause of the failure (be sure you
have found the cause, and not simply a symptom).

2. Eliminate the cause of the failure.

3. Drain the entire circuit, including cylinders, motors,
reservoirs, control valves, heat exchangers, and
filters.

4. Remove system lines and components. Flush with
a compatible solvent, or clean filtered oil to remove
contamination that may have entered the system
when the pump failed. Be certain that fluid has been
flushed from cylinders.

5. Visually inspect components for possible
contamination, and for proper operation. Pay special
attention to wipers on cylinder rods. Be sure that the
rods are free of nicks and scratches.

6. Flush the reservoir using pressurized solvent. Use
clean, dry, lint-free cloths to ensure a clean interior.
Inspect the filler/breather (if used) and the suction
strainer for cleanliness.

7. Install a new filter with a 10 micron or better
element, and low Beta ratio. If the machine does not
have a filter, install one that meets these
specifications.

8. Fill the reservoir with new, FILTERED oil of the
recommended type. Be certain to monitor the fluid
level, since the entire system (not just the reservoir)
must be filled.

9. Re-install all system lines. Visually inspect to make
sure they are clean, and free of contamination. Be
sure that all inlet fittings are tight and clean.

10. Install the new pump.

11. Follow the start-up procedures given on pages 2
and 3 of this manual.

12. Cycle all cylinders and operate all motors at
normal operating speeds for 20 minutes. While
operating, observe the reservoir fluid level, since all
components will be filling with hydraulic fluid.

13. Replace the filter element, and check the fluid
level. Add new, clean, filtered oil if required.

To assure that your replacement pump performs at
the same level as the original pump, check daily for
proper fluid level, filter condition and leaks. Change
fluid at recommended intervals. Good fluid
maintenance is especially important when using other
than mineral based fluids.

TROUBLESHOOTING GUIDE

Component problems and circuit problems are often
interrelated. Apoorly designed circuit may operate
with apparent success, but cause a component of the

not the cause of the problem. The following general
guide is offered to help you locate and eliminate the
cause of problems by studying their effects.

system to fail. The component failure is the effect,

Problem Possible Cause Look For

Noisy Pump Air in fluid Leak in suction line

Leak in shaft seal
Low fluid level
Turbulent fluid
Return lines above fluid level
Gas leak from accumulator
Excessive pressure drop in the inlet line

from a pressurized reservoir

Cavitation in pump rotating group Fluid too cold, too viscous or too heavy

Shaft speed too high
Suction line too small, or collapsed
Suction line strainer dirty or too small

Form No. R92.00 Rev. 10/03

Continued on Page 4

3

TROUBLESHOOTING GUIDE

Problem Possible Cause Look For

Noisy Pump Misaligned shaft Faulty installation

Distortion in mounting
Axial interference
Faulty coupling

Mechanical fault in pump Piston and shoe loose or failed

Bearing failure
Incorrect port plate selection or index
Eroded or worn parts in

displacement control

Erosion on Air in fluid Refer to above
barrel
and

Cavitation Refer to above

port plate
High wear Excessive loads Reduce speed or pressure setting

in pump

Contaminant particles in fluid Improper filter maintenance

Filter too coarse
Dirty fluid introduced to the system
Reservoir or breather cap open to

atmosphere

Improper line replacement

Improper fluid Fluid too thick or too thin for operating

temperature range

Fluid breakdown due to age, temperature

or shearing effects
Incorrect additives in new fluid
Reduced additive effectiveness due to

chemical aging

Improper repair Incorrect parts, procedures, dimensions

or finishes

Unwanted water in fluid Condensation

Faulty breather/strainer
Heat exchanger leaking
Faulty clean-up practice
Water in makeup fluid

Pressure Cogging or erratic load movement Mechanical considerations
shocks

Slow acting relief valve Replace with fast acting relief valve
Worn relief valve Repair or replace, as needed
Worn compensator Repair or replace, as needed
Insufficient line capacitance (line volume, Increase line size or length

line stretch, accumulator effects)

Fluid Excessive pump leakage Recheck case drain flow,
overheats repair as needed

Fluid too thin, minimum operating viscosity

60 SUS (10Cst)
Improper assembly

Faulty relief valve Set too low (compared to load

or compensator)
Instability caused by back pressure,

or worn parts

Faulty compensator Set too high (compared to relief)

Worn parts

Faulty heat exchanger Water turned off, or insufficient flow

Ambient water temperature too high
Fan clogged, restricted or inoperative
Mud or scale buildup
Intermittent hydraulic fluid flow through

exchanger

Continued on Page 5

4

Form No. R92.00 Rev. 10/03

TROUBLESHOOTING GUIDE (continued)

Problem Possible Cause Look For

Fluid Faulty reservoir Fluid level too low
overheats

(continued)

Entrained air in fluid
Improper, or no baffles
Poor air flow, or ambient air temperature

too high around reservoir

Heat pick up from adjacent equipment

Decrease in Loose compensator adjusting screw Tighten adjusting screw ( No.11 in
set pressure Fig. 14, exploded view)

Defective function or relief valves Repair or replace relief valve

Check relief valve setting

Reservoir fluid level too low Replenish fluid

Check drain (below 5% of discharge at

rated pressure)

Deteriorating pump performance Check pump internal components for wear,

repair or replace as needed.

Pressure Pump turning backward Change the rotating direction
does not rise

Reservoir fluid level too low Replenish fluid
Relief valve or compensator set wrong Readjust and lock
Relief valve or compensator defective Repair or replace
Clogged suction line Inspect and clean suction strainers

Open gate valve

Deteriorating pump performance Check pump internal components for wear,

repair or replace as needed.

Insufficient Reservoir fluid level too low Replenish fluid
flow

Suction line not sealed Tighten fittings
Improper pump stroke control adjustment Readjust as required

Repair or replace as required

Deteriorating pump performance Change compensator
Worn compensator

PISTON PUMP DISASSEMBLY
Precautions

CAUTION – Before performing any service

operation on any pump, be sure that all
pressure has been relieved from BOTH
SIDES of the system.

CAUTION – Before performing any service
operation on any pump, disconnect or lock
off power supply.

CAUTION – Do not attempt to remove the
Barrel Spring. The Barrel Spring is

assembled under high compression. Any

attempt to remove the Barrel Spring will
cause sudden decompression, and may inflict serious
personal injury. The Barrel Spring is NOT field
serviceable. Should the Barrel Spring require service,
the pump must be returned to Continental Hydraulics
or an Authorized Repair Center.

1. Please refer to the exploded view (Figure 14
through 17) for proper names and locations of all
parts.

Form No. R92.00 Rev. 10/03

2. Pump disassembly for inspection and repair should
be undertaken only in the following cases:

Malfunction or leakage due to damage or
wear.
When troubleshooting procedures contained
in this manual do not solve a problem.

3. Disassembly should be done only as far as
necessary to replace or repair worn parts.

4. Perform assembly and disassembly in a clean
environment.

5. Avoid dropping, damaging or contaminating the
machined parts of the pump and compensator.

6. After disassembly, coat the internal parts with a film
of clean oil, and protect them from dirt and moisture.

7. Prior to disassembly, measure and record the
length of the protruding part of adjusting screws (22)
and (28-11) from Figure 14, and if necessary, (18)
from Figure 16 or 17. This will simplify resetting the
pump after reassembly.

5

HPV REPAIR PROCEDURES

DISASSEMBLY, INSPECTION and REASSEMBLY
GENERAL

Disassembly in the field by other than an Authorized
Repair Center technician, whether for repair or
modification will void warranty.

NOTE: Certain steps in this procedure
require special tools, and the application
of great force. Care should also be taken

to contain residual oil during
disassembly. Before beginning, read this section
through to make sure that you are prepared for
the job.

General Disassembly Procedure

1. Drain pump body (1)
via Case Drain Ports.
(Figure 4)

2. Position the pump with
Case Drain Ports up.

3. Remove four
compensator screws (71)
and then remove remove
compensator (28) and O­rings (32).

4. Remove four cover
retaining screws (46). Loosen two diagonally
positioned screws first. Then loosen the remaining
two diagonally positioned screws. Remove the
screws and carefully separate the cover (2) from the
pump body. If the gasket holds the cover in place, tap
the cover lightly with a fiber hammer on the side
opposite the compensator.

NOTE: The port plate (4) may cling to the cover (2)
due to oil film between parts. DO NOT ALLOW THE
PLATE TO FALL AND BE DAMAGED.

5. Gently remove the port plate (4) from the barrel (3)
face.

6. Place the pump on a work bench with the shaft in a
horizontal position. Remove the barrel (3) with piston
assembly (5), guide ball (14), guide plate (15), and
dowel pins (56) as a unit.

7. Place the barrel (3) on a clean cloth or plastic film.
Hold the side of the guide plate (15) and gently
remove the piston assembly.

8. Remove the guide ball (14) and dowel pins (56).

9. Place the pump body (1), shaft down, on a fixture
designed to keep it from toppling. Protect with a dust­proof plastic film.

10. Place the cover (2) with the assembled guide
sleeve (64), plunger (21) and needle bearing (65) on
a work bench. The guide sleeve must face up.
Protect the parts with a dust-proof plastic film.

NOTE: Following completion of disassembly
procedure steps 1 through 10, necessary pump
inspection can be performed. Further disassembly
may be required if the following inspection steps
reveal specific problems.

11-1. When the barrel (3) is laid flat, the dowel pins
(56) must protrude slightly. If otherwise, or if the
dowel pins are easily pushed in, replace the barrel.

Case Drain

Ports

Figure 4

11-2. If the hanger (9) has little or no inclination
against the shaft (8), or if it can easily be moved by
hand, go to steps 12 through 15.

11-3. If shaft seal leakage or excessive ball-bearing
play is apparent, go to steps 16 through 21.

11-4. If compensator function is erratic, go to steps 23
through 33, as required.

Hanger Removal

12. Place the pump body in a large vise, or on a
working surface adapted to hold the pump body firmly.

13. Remove the trunnions (10) using the blind
threaded holes, and the appropriate trunnion removal
tool. See Figure 9 on page 13 for trunnion removal

tool specifications.

CAUTION: The hanger may be under
tension, and should be secured to
prevent injury.

14. Remove the hanger (9), spring seat (20), and
spring (19) in this order.

15. Proceed to HANGER INSPECTION and
TRUNNION INSPECTION, page 9.

Shaft Removal and Disassembly

16. As required, remove the key (70). Tap gently at
the end of the key with a hammer or chisel if it is
difficult to remove.

17. Remove the retaining ring (41) with a snap ring
pliers.

18. Remove the shaft (8). Pull the shaft toward the
cover. Tap lightly with a fiber hammer on the end of
the shaft if it is difficult to remove.

19. Replace the ball-bearing if it shows excessive
wear, or if noise is heard when rotating the outer race
by hand.

20. To replace the ball bearing, remove retaining rings
(68), and remove the ball bearing (69) with a hand
press or by light hammering.

21. If oil leaks are observed, the shaft seal must be
replaced. Remove the shaft seal (38) from the pump
body (1). Use a push rod of smaller diameter than
the outside diameter of the shaft seal.

NOTE: Do not reuse seals. See Parts List, page 17,
Item 38 for replacement part numbers.

22. Proceed to SHAFT INSPECTION, page 9, and
BALL BEARING INSPECTION, page 11.

Compensator Disassembly

23. Loosen the hex nut (28-12) and remove the
adjusting screw (28-11) from the end cap (28-3).

24. Remove the end cap (28-3).

25. Remove the spring (28-6) and spring seat (28-5).

26. Remove the spool (28-2).
Continue for Codes 7, 19, and 26 compensators.

Item numbers refer to figures 16 and 17, page 20.

27. Loosen the hex nut (12) and remove the adjusting
screw (18) from the body (1).

28. Remove the spring (7) and cone (16).

29. Proceed to PRESSURE COMPENSATOR
INSPECTION, page 11.

6

Form No. R92.00 Rev. 10/03

HPV REPAIR PROCEDURES (continued)

NOTE: If the cone is badly worn or damaged, perform
the following steps.

30. For Code 7 or 19 compensators, remove the plug
(20). Using a rod, tap the seat (15) out from the
opposite end.

31. For Code 26 compensators, remove the fitting
(27) and adjusting screw (18) as an assembly.

32. Remove the dowel pin (24) and ball (17).

33. Remove the fitting (29). Using a rod, tap the seat
(15) out from the opposite end.

Rework Limits for Wear Parts

Barrel Bores − Measure each bore in four places,
including one place deep within the bore, where the
piston doesn’t run. Replace the barrel if the
difference in measurements exceeds .0004 in. or .010
mm.

Barrel Face − May be lapped no more than .0002 in.
or .005 mm measured by before and after depths of
oil grooves on barrel face.

Pistons (5) − Measure each piston in four places,
including one at the shoe end, where the piston
doesn’t enter the barrel. Replace Piston if the
difference in measurements exceeds .0006 in. or .015
mm.

Shoe, Piston Assembly − Replace assemblies if end
play exceeds .003 in. or .076 mm.

Shoe, Face − May be lapped up to .004 in. or .102
mm. The difference in shoe flange thickness
between the thinnest and thickest of nine shoes
should not exceed .0012 in. or. 03 mm.

Port Plate (4) − May be lapped .006 in. or .152 mm.
Maintain flatness of .0002 in. or .005 mm.

Wear Plate (16) − Do not lap. Replace if there are
any indications of wear or bending.

Guide Plate (15) − Do not lap. Measure thickness at
several places. Replace if thickness varies more than
.004 in. or .102 mm.

INSPECTION PROCEDURES

Part (Item No.) Inspection Procedure Corrective Action

Check for cracks around tapped holes.

Pump Body Check for cracks around retainer ring groove. Replace if cracked.

(1) Perform dye penetrant or magnetic particle inspection over

entire housing when oil leakage is observed.

Visually inspect for obvious defects
Check for excessive wear in guide sleeve (64). Axial scratches

should not be detectable with a fingernail. Diameter difference

Cover must not exceed .001 in. or .025 mm when measured at several Replace if defective

(2) random points.

Check for excessive play between drive shaft (8) and needle

bearing (65). (Maximum radial play is .003 in. or .076 mm.)

Repair by lapping until

Visually inspect the barrel face for uniform minute concentric nicks. scratches are removed.

Do not exceed rework

limits listed above.

Visually inspect for deep, localized nicks. Replace barrel. Flush

Barrel reservoir and circuit.

(3) Replace barrel.

Check for

Visually inspect for signs of seizure, scoring or discoloration. correct hydraulic fluid

type, temperature rise,

excessive pressure.

Correct as needed.

Form No. R92.00 Rev. 10/03

Continued on Page 8

7