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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
SEMITRAILER LOCKED IN TILTED
POSITION
SYSTEM INOPERATIVE
SYSTEM OPERATES ERRATICALLY
SYSTEM OPERATES SLOWLY
SYSTEM OPERATES TOO FAST
PROBABLE CAUSE
Velocity fuse activated
Not enough oil in system
Wrong oil in system
Filter dirty or clogged
Hydraulic lines dirty or collapsed
Air leaks in pump suction line
Worn or dirty pump
Badly worn components
Leakage
Excessive load
Slipping or broken pump drive
Air in the system
Cold oil
Dirty or damaged components
Restriction in filters or lines
Not enough oil in system
Oil viscosity too high, or "cold oil"
Low pump drive speed
Low oil level
Air in system
Badly worn pump, valves, cylinders, etc.
Restrictions in lines or filter
Improper adjustments
Oil leaks
Wrong size or incorrectly adjusted
restrictor
Engine running too fast
TROUBLESHOOTING GUIDE
SOLUTION
Raise the trailer slightly (to reset the
velocity fuse), then lower the trailer
slowly.
Fill, check for leaks.
Change oil, see specifications (See
Table 4-1).
Drain oil and replace filter.
Clean or replace as necessary.
Repair or replace as necessary.
Clean, repair or replace. Check for
contaminated oil. Drain and flush.
Examine for internal leakage. Replace
faulty components. Check for cause of
wear.
Check all components, and relief valve for
proper settings.
Check unit specifications for load limit
(See "Standard Specifications" on
page 2-1.).
Repair or replace couplings. Check for
alignment
Check suction side of system for leaks.
Repair leaks.
Allow ample warm-up time. Use proper
weight oil for operating temperature.
Clean or repair as needed.
Clean and/or replace filter or lines.
Fill and check for leaks.
Allow oil to warm up before operating.
Increase engine speed (check pump
owners manual for specifications).
Check reservoir and add oil as necessary.
Check suction side for leaks. Repair leaks.
Repair or replace faulty component(s) as
necessary.
Clean and/or replace filter or lines.
Check orifices, relief valves, etc. Adjust as
necessary.
Tighten fittings. Replace seals, gaskets
and damaged lines.
Replace or adjust as necessary.
Reduce engine speed
5-7
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