Lull 944E-42 Service Manual - Manual (Page 361)

8.109 Model 644E-42/944E-42 Rev. 6/04
Hydraulic System
Not
OK
Inspect pump. Refer to
Hydraulic Testing
pages 8.12 through 8.54.
Check the cycle times for
boom LIFT and boom
EXTEND to determine pump
performance. Pump flow
directly controls these cycle
times. Refer to Section 2.5.6,
“Hydraulic Cylinder
Performance Specifications,”
for correct cycle times.
Not
OK
If the transfer carriage
cylinder extends slowly.
Repair/replace transfer
cylinder.
Check transfer cylinder for
seal leaks.
NOTE:
When checking pressures in
circuits, refer to Section 8.7,
“Hydraulic System Testing,” for
correct pressure readings.
NOTE:
Before checking any hydraulic
circuits, verify that the transfer
carriage is not binding and that
the rollers and pads are
operating freely and have the
proper clearance. Refer to
Section 11.3, “Transfer Carriage
Maintenance,” for correct
inspection procedures.
Not
OK
Check pilot pressure at “PPG”
port of accumulator charge/
secondary function valve.
Adjust/repair/replace
pressure reducing cartridge
on accumulator charge/
secondary function valve.
Not
OK
Check port relief at main
control valve
Replace the relief valve on
transfer section of main
control valve.
If OK
If OK
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