Manitowoc 999, Service And Maintenance Manual

Page: 263 / 298

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