JLG 450A_AJ Series II Service Manual - Manual (Page 323)

SECTION 5 - HYDRAULICS
3121180 – JLG Lift – 5-33
Removal and Installation of 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).
Removal and Installation of FNR and NFPE
Control Orifices
NOTE: Future models may contain an orifice plate between
module 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
installation of new O-rings. The pressure setting may be
changed. Setting will vary for different charge flows
depending on charge pump size and pump speed. Fac-
tory setting is set relative to case pressure at 1800 rpm.
Actual charge pressure will vary 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, charge relief valve setting can be
changed. An approximate 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 5-33. Shim Adjustable Charge Relief Valve
Components