TROUBLESHOOTING GUIDE
5-7
Hydraulic System
Most hydraulic system failures follow the same pattern: a
gradual or sudden loss of pressure or flow with a
resulting loss of cylinder or motor power. Any one of the
system’s components may be at fault. By following
step-by-step procedures, the trouble can be located in a
short time.
PROBLEM
PROBABLE CAUSE
SOLUTION
SEMITRAILER LOCKED IN TILTED
POSITION
Velocity fuse activated
Raise the trailer slightly (to reset the
velocity fuse), then lower the trailer
slowly.
SYSTEM INOPERATIVE
Not enough oil in system
Fill, check for leaks.
Wrong oil in system
Change oil, see specifications
Filter dirty or clogged
Drain oil and replace filter.
Hydraulic lines dirty or collapsed
Clean or replace as necessary.
Air leaks in pump suction line
Repair or replace as necessary.
Worn or dirty pump
Clean, repair or replace. Check for
contaminated oil. Drain and flush.
Badly worn components
Examine for internal leakage. Replace
faulty components. Check for cause of
wear.
Leakage
Check all components, and relief valve for
proper settings.
Excessive load
Check unit specifications for load limit
(See “Standard Specifications” on
page 2-1.)
Slipping or broken pump drive
Repair or replace couplings. Check for
alignment
SYSTEM OPERATES ERRATICALLY
Air in the system
Check suction side of system for leaks.
Repair leaks.
Cold oil
Allow ample warm-up time. Use proper
weight oil for operating temperature.
Dirty or damaged components
Clean or repair as needed.
Restriction in filters or lines
Clean and/or replace filter or lines.
Not enough oil in system
Fill and check for leaks.
SYSTEM OPERATES SLOWLY
Oil viscosity too high, or “cold oil”
Allow oil to warm up before operating.
Low pump drive speed
Increase engine speed (check pump
owner’s manual for specifications).
Low oil level
Check reservoir and add oil as necessary.
Air in system
Check suction side for leaks. Repair leaks.
Badly worn pump, valves, cylinders, etc.
Repair or replace faulty component(s) as
necessary.
Restrictions in lines or filter
Clean and/or replace filter or lines.
Improper adjustments
Check orifices, relief valves, etc. Adjust as
necessary.
Oil leaks
Tighten fittings. Replace seals, gaskets
and damaged lines.
SYSTEM OPERATES TOO FAST
Wrong size or incorrectly adjusted
restrictor
Replace or adjust as necessary.
Engine running too fast
Reduce engine speed
