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 O-
rings (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 dust-
proof 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.
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
Case Drain
Ports
Figure 4
