JLG 600SC_660SJC Service Manual - Manual (Page 290)

SECTION 8 - HYDRAULICS
8-30 – JLG Lift – 3121157
5. Install a new O-ring on the valve plug. Reinstall the
poppet, spring, and plug (with shims and O-ring)
into the pump housing [55-135 Nm (40-100 ft•lbf)].
SCREW ADJUSTABLE STYLE
1. Before removing the screw adjustable relief valve
plug, mark the plug, lock nut, and housing so as to
approximately maintain the original adjustment
when assembling, Remove the screw adjustable
charge relief valve plug by loosening the lock nut [1-
1/16 in Hex] and unscrewing the plug [8 mm Int.
Hex]. Remove the O-ring from the plug.
2. Remove the spring and poppet from the housing.
3. Inspect the poppet and mating seat in the housing
for damage or foreign material.
4. Install a new O-ring on the valve plug. Reinstall the
poppet and spring. Reinstall the plug with its lock
nut [47-57 Nm (34-42 ft•lbf)], aligning the marks
made at disassembly.
5. Check and adjust, if necessary, the charge pressure.
For screw adjustable "anti-stall" charge relief valves,
an approximate rule of thumb is 2.8 bar / quarter
turn (40 psi / quarter turn).
To confirm the charge relief valve setting, measure
charge pressure (port M3) with the pump in stroke.
The charge pressure should level off when the relief
setting is reached.
Shaft Seal and Shaft Replacement
A lip type shaft seal is used in Series 42 pumps. This seal
and/or the shaft can be replaced without major disassem-
bly of the unit. Replacement generally requires removal of
the pump from the machine.
1. Lock Nut
2. O-ring
3. Plug 4. Spring T-Seal
5. Poppet
Figure 8-25. Screw Adjustable Charge Relief
Valve Components
1. Retaining Ring 2. Seal Carrier Assembly
Figure 8-26. Shaft Seal Components
1. O-ring
2. Seal
3. Seal Carrier 4. Sealant may be used on outside diameter
5. Inside Lip (face down)
6. Press Seal to Bottom of Seal Carrier
Figure 8-27. Installation of Shaft Seal