Manitowoc 999 Service And Maintenance Manual page 263

999 SERVICE/MAINTENANCE MANUAL
3,500 psi or more
Check for 3,500 psi at rear drum flushing
valve test port while enabling another
jacking cylinder on lower accessory valve.
3,500 psi or more
Exchange both counterbalance valve
cartridges on problem jacking cylinder. Is
cylinder enabled with handle movement?
Yes
Replace counterbalance valve.
Repair or replace jacking cylinder.
Manitowoc
Problem 24
Jacking cylinder(s) will not extend or retract.
POSSIBLE CAUSES
Not in setup mode; Faulty control valve section;
Low pump pressure; Bad pump; Faulty counterbalance valve.
CHECKS
Check for 3,500 psi at rear drum flushing valve test port while manually
enabling jacking cylinder on lower accessory valve.
No
Published 05-16-17, Control # 233-03
3,500 psi or less
Is crane setup mode selected and confirmed?
Yes
Select and confirm setup mode.
Does system develop any pressure?
Yes
Adjust rear drum system pressure to
3,500 psi when jacking handle is moved.
(See Test 19.)
Is accessory pressure switch tripping (bank 7 change
by 64 on Accessory System screen), when jacking
handle is moved? (See Test 25.)
Yes
Repair or replace accessory pressure switch/wiring.
Repair or replace rear drum pump. Consult dealer/factory.
TROUBLESHOOTING
No
No
No
10
10-27