22
MHD56114 - Edition 4
TROUBLESHOOTING
This section provides basic troubleshooting information. Determination of specific causes to problems are best identified by thorough
inspections performed by personnel instructed in safety, operation and maintenance of this equipment. The chart below provides a brief
guide to common winch symptoms, probable causes and remedies.
SYMPTOM
CAUSE
REMEDY
Winch will not operate. No air supply to winch.
Check air supply line connections and hoses.
Winch is overloaded.
Reduce load to within rated capacity.
Emergency Stop Valve engaged.
Reset Emergency Stop Valve.
Shipping plugs may still be in place. Remove shipping plugs in valve.
Drum brake not released.
Disengage manual drum brake or refer to “Automatic Drum Brake” below.
Load continues to move
when winch is stopped.
Brake(s) slipping.
Check brake band adjustment and brake band lining wear. Disassemble and
inspect disc brake.
Winch motor controls sticking.
Check pendant button/throttle lever returns to normal (neutral) position
when released.
Disassemble, inspect and repair the pilot air control valve. Verify spool
adjustment.
Winch does not lift load Motor may be damaged.
Remove and disassemble motor. Examine all parts and replace any that are
worn or damaged.
Insufficient air supply.
Verify air supply pressure and volume at winch inlet meets the requirements
listed in the “SPECIFICATIONS” section. Clean air line filter.
Throttle lever or
pendant buttons move
but winch does not
operate.
Motor may be damaged.
Disassemble and clean the motor and replace any worn or damaged parts.
Insufficient air supply.
Ensure the air pressure at the winch inlet is at least 90 psig (6.3 bar/630
kPa) at rated volume. Clean air line filter.
Emergency Stop Valve engaged.
Reset Emergency Stop Valve.
Overload Device engaged.
Reduce load to within rated capacity of winch and reset Emergency Stop
Valve.
Air leak.
Check hose connections. Check hose lines for wear or damage. Replace
worn or damaged hoses.
Motor runs hot or
makes excessive noise
during operation.
Improper lubrication.
Set lubricator to provide 6 to 9 drops of oil per minute.
Damaged or broken motor internal
parts.
Disassemble and repair motor.
Winch runs slow.
Improper hose or fitting sizes.
Check fittings, connections and hoses for correct size and length. Replace
parts that may cause restricted air flow. Inspect air line filter.
Motor may be damaged.
Remove and disassemble motor. Inspect all parts and replace all worn or
damaged parts.
Brake(s)may not be releasing.
Refer to brake sections below.
Air lines freeze.
Water in air supply.
Install or drain air system moisture traps, moisture collecting air receivers
and compressor aftercoolers. After corrective action has been taken,
disconnect lines at winch inlet and purge with clean, dry air or nitrogen.
Automatic Drum Brake:
Brake will not release. Damaged or leaking cylinder seals.
If air is noticed escaping from around the cylinder cover when attempting to
release the brake disassemble and inspect brake. Replace all seals and repair
or replace worn or damaged parts.
Dirty filter in air supply.
Clean or replace filter.
Brake does not set
when applied.
Hole in exhaust valve restricted or
exhaust valve damaged.
Remove and inspect exhaust valve. Clean hole or replace damaged exhaust
valve.
Automatic Disc Brake:
Brake fails to release.
Low air supply pressure.
Ensure supply air pressure at the brake inlet is at least 50 psig (3.4 bar/340
kPa).
Leaking diaphragm.
Disassemble brake and replace diaphragm.
No release pressure at the brake port. Verify proper operation of winch controls.
