JLG 740A, Service And Maintenance Manual

Page: 313 / 408

SECTION 5 - HYDRAULICS
3121160 – JLG Lift – 5-27
Shaft Seal Replacement
A lip type shaft seal is used in the pump and can be
replaced without major disassembly of the unit. Replace-
ment of the shaft seal requires removal of the pump from
the machine.
REMOVAL
1. Using the appropriate snap-ring pliers, remove the
retaining ring (K010) from the housing.
2. Remove the shaft seal (K020) from the bore in the
pump housing and discard. Avoid damaging the
pump housing or shaft. Puncture the face of the seal
with a packing hook, or use a slide-hammer type
puller to remove the seal.
INSTALLATION
1. Inspect the pump housing and new seal for dam-
age. Inspect the sealing area on the shaft for rust,
wear, or contamination. Polish the sealing area on
the shaft if necessary.
2. Lubricate the lip of the new shaft seal with clean
hydraulic fluid. Place a protective sleeve over the
shaft end to prevent damage to the seal during
installation.
PREMATURE BEARING FAILURE CAN RESULT IF THE SHAFT
SEAL CONTACTS THE SHAFT BEARING. PRESS THE SEAL INTO
THE HOUSING ONLY FAR ENOUGH TO CLEAR THE RETAINING
RING GROOVE.
3. Keeping the seal perpendicular to the shaft, press
the new seal into the housing just far enough to
clear the retaining ring groove. Install seal with the
cupped side toward the shaft bearing. Do not dam-
age the seal during installation.
4. Using the appropriate snap ring pliers, install the
seal retaining ring.
5. Remove the installation sleeve.
Control Assembly
DISASSEMBLY
1. Remove the four screws (C300) holding the control
housing onto the end cap.
2. Remove the control and discard the three interface
O-rings (C200).
3. Remove the Pressure Compensator set screw
(C102), Pressure Compensator adjustment screw
(C138),O-ring (C136), springs (C135, C134), and
seat (C133). Discard the O-ring.
K010
K020
Figure 5-18. Shaft Seal and Retaining Ring
C117
C118
6mm
C116
C117
C114
C115
C113
C200
C138
6mm
C136
C135
C134
C133
C132
C103A
C112
C106A
C106
3/16 in
11-14 N•m
[8-10 lbf•ft]
C103
3/16 in
11-14 N•m
[8-10 lbf•ft]
C300 (4pl.)
5mm
15-18 N•m
[11-13 lbf•ft]
C102 (2pl.)
4mm
7-11 N•m
[6-8 lbf•ft]
C107A
C107
3/16 in
11-14 N•m
[8-10 lbf•ft]
Figure 5-19. Control Assembly