SkyTrak 8042 Service Manual - Manual (Page 436)

8.21 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.
Not
OK
If the extend/retract cylinder
does not extend, check
cable connections at main
control valve.
If OK
Repair/replace cable
connections. Ensure extend/
retract 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
Not
OK
Check pump flow. Repair/replace pump.
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
Check packing on
extend/retract cylinder.
Repair/replace
extend/retract cylinder.
If OK
Not
OK
On 10054 only, check the
solenoid valve on the extend
lockout valve.
Replace solenoid valve.
Not
OK
On 10054 only, check the
extend lockout valve.
Replace the extend lockout
valve.
If OK
If OK
If OK
Not
OK
Check the counterbalance
valve on the extend/retract
cylinder.
Replace counterbalance
valve.
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
Check the extend/retract
cylinder packing.
Replace counterbalance and/
or pilot-operated check valves
on the extend/retract cylinder.
If the extend/retract cylinder
drifts or reacts slowly, check
counterbalance and pilot-
operated check valves on the
extend/retract cylinder.
If OK
Repair/replace
extend/retract cylinder.