Lull 944E-42 Service Manual - Manual (Page 321)

8.69 Model 644E-42/944E-42 Rev. 6/04
Hydraulic System
Not
OK
Not
OK
Not
OK
If park brake fails to hold, check
the “PBG” port on the
accumulator charge/secondary
function valve. Should read 0 psi.
If park brake fails to release,
check the “PBG” port on the
accumulator charge/secondary
function valve. Should read
500-600 psi (34,5-41,4 bar).
Check pressure reducing
cartridge on accumulator charge/
secondary function valve.
Refer to Section 9.14.6,
“Parking Brake Switch.”
Not
OK
Within the front axle:
If not holding, check the park
brake springs.
If not releasing, check the
piston seals.
Refer to ZF Axle Repair
Manual, Model MS-T 3045,
ZF part # 5871 550 002. JLG
part # 8990419 (644E Only)
or ZF Axle Repair Manual,
Model MS-T 3060, ZF part #
5871 560 002. JLG part #
8990430 (944E Only)
Install seal kit/replace
solenoid valve cartridge.
If OK
Adjust/repair/replace
pressure reducing cartridge.
If OK
Check solenoid valve
cartridge.
Check solenoid valve on the
accumulator charge/
secondary function valve.
If OK
NOTE:
When checking pressures in
circuits, refer to Section 8.7,
“Hydraulic System Testing,” for
correct pressure readings.
Not
OK
Check front brake discs for
wear.
Refer to Section 5.6.1, “Brake
Disc Inspection.”
If OK
Before troubleshooting any
hydraulic circuit, ALWAYS
begin by checking the
following:
1. Hydraulic oil level in the
reservoir
2. All hoses, tubes, fittings
for leaks, kinks,
interference, etc.
3. Air in the lines