SkyTrak 8042 Service Manual - Manual (Page 440)

8.25 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
NOTE:
When checking pressures in
circuits, refer to Section 8.7,
“Hydraulic System Testing,” for
correct pressure readings.
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
Not
OK
If OK
Repair/replace cable
connections. Ensure lift/lower
section of main control valve is
functioning.
Not
OK
Check main relief pressure on
main control valve.
Adjust/repair/replace relief
valve on main control valve.
If OK
Not
OK
Check pump flow. Repair/replace pump.
Not
OK
Check packing on
lift/lower cylinder(s).
Repair/replace
lift/lower cylinder(s).
If OK
If the lift/lower cylinders do
not raise, check the cable
connections at the main
control valve.
Not
OK
Check the counterbalance
valve on the lift/lower
cylinders.
Replace counterbalance
valve.
If OK
NOTE:
Refer to Section 2.5.4,
“Performance Specifications,” for
approximate cylinder cycle
times. The operation of the
system function should
approximate the times listed.
Not
OK
Not
OK
Check the packing on the lift/
lower cylinders.
Replace counterbalance and/
or pilot-operated check valves
on the lift/lower cylinders.
If the lift/lower cylinders drift
or react slowly, check
counterbalance and pilot-
operated check valves on the
lift/lower cylinders.
If OK
Repair/replace
lift/lower cylinders.