Service Manual Instruction Manual

SECTION 5 - HYDRAULICS
3121616 – JLG Lift – 5-67
5. Install new O-ring on valve plug. Reinstall poppet,
spring, and plug (with shims and O-ring) into pump
housing. Torque to 40-100 ft-lb (55-135 Nm).
SCREW ADJUSTABLE STYLE
1. Mark plug, lock nut, and housing to maintain original
adjustment before removing screw adjustable relief valve
plug. Loosen lock nut (1-1/16" Hex) and remove plug (8
mm Int. Hex). Remove O-ring from plug.
2. Remove spring and poppet from housing.
3. Inspect poppet and mating seat in housing for damage
or foreign material.
4. Install new O-ring on valve plug. Reinstall poppet and
spring. Reinstall plug and lock nut. Torque to 34 - 42 ft-lb
(47-57 Nm), aligning marks made at disassembly.
5. Check and adjust charge pressure if necessary. For screw
adjustable “anti-stall” charge relief valves, an approxi-
mate rule of thumb is 2.8 bar/quarter turn (40 psi/quar-
ter turn).
6. Measure charge pressure (port M3) with pump in stroke.
Charge pressure should level off when relief setting is
reached.
Shaft Seal and Shaft Replacement
A lip type shaft seal is used in Series 42 pumps. Seal and shaft
can be replaced without major unit disassembly. Replacement
generally requires removing pump from machine.
1. Lo ck Nu t
2. O-R in g
3. Plu g
4. Spr ing T- Seal
5. Po pp et
Figure 5-126. Screw Adjustable Charge Relief Valve
Components
1. Reta inin g R i ng 2 . S ea l Ca rr ie r A sse mbl y
Figure 5-127. Shaft Seal Components
1. O-Ring
2. Seal
3. Seal Ca rr ier
4. Sealant may be used on outside diameter
5. Inside Lip (face down)
6. Pre ss Se al t o B ott om of S e al Ca rri er
Figure 5-128. Shaft Seal Installation