JLG 600SC_660SJC Service Manual - Manual (Page 184)

SECTION 5 - HYDRAULICS
5-40 – JLG Lift – 3121607
Remove and Install FNR and NFPE Modules
1. Clean pump and module housings.
2. Remove four screws retaining module to pump housing (4
mm Int. Hex). Remove module from housing.
3. Remove O-rings from the control ports. Examine ports
for cleanliness.
4. Clean sealing surfaces.
5. Replace locator pin.
6. Install new O-rings.
7. Replace screws. Torque to 3.5 - 4.5 ft-lb (4.7-6.1 Nm).
Remove and Install FNR and NFPE Control Orifices
NOTE: Future models may contain an orifice plate between mod-
ule and pump housing. This will take the place of the orifice
plugs beneath the servo piston cover.
1. Remove servo piston cover.
2. Remove orifice plug (1/8" Int. Hex).
3. Examine orifice and port for cleanliness.
4. Install orifice plug. Torque to 1.5 - 2.5 ft-lb (2.0-3.4 Nm).
Charge Relief Valve
Charge relief valve may be removed for cleaning and installa-
tion of new O-rings. Pressure setting may be changed for dif-
ferent charge flows depending on charge pump size and
pump speed.
Factory setting is set relative to case pressure at 1800 rpm.
Actual charge pressure varies at different speeds.
SHIM ADJUSTABLE STYLE
1. Remove shim adjustable charge relief valve plug (1" Hex)
from pump housing. Remove O-ring from plug.
2. Remove spring and poppet from housing.
3. Do not alter shims which may be installed between
spring and valve plug, or interchange parts with another
valve. Inspect poppet and mating seat in housing for
damage or foreign material.
4. If desired, change charge relief valve setting. An approx-
imate rule of thumb is 4 bar / 1.25 mm (58 psi / 0.050 in).
Effective setting will vary.
To confirm charge relief valve setting, measure charge
pressure (port M3) with pump in stroke. Charge pressure
should level off when relief setting is reached.
1. Plug
2. O-Ring
3. Shims
4. Spring T-Seal
5. Poppet
Figure 5-68. Shim Adjustable Charge Relief Valve
Components