PAGE 12
TROUBLE SHOOTING
CONTINUED
PROBABLE CAUSE
FAILURE
a)
Brake plates or divider plates have been damaged by
contamination in the hydraulic fluid, or lack of circulation
flow in the brake housing.
b)
Brake piston is seized in the brake housing because of
contamination in the hydraulic fluid.
c)
Excessive back pressure in the return line causes the
brake to be released.
d)
Control valve has incorrect spool, which traps hydraulic
pressure in the brake piston when the control valve handle
is returned to neutral position. For proper function of the
automatic brake, both pressure ports of the winch must be
open to the reservoir in neutral position of the control valve.
e)
Wire rope is fastened to the incorrect cable anchor slot.
f)
Sprag clutch is damaged or surfaces where sprag
clutch engages on motor drive shaft or brake hub are
worn or indented.
g)
Winch supplied with external brake release option is
not plumbed per HYDRAULIC CIRCUIT. Failure to
vent external brake release port to reservoir may trap
pressure and cause winch brake to slip.
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a)
Pump is too slow. Pump rpm must be maintained at
normal operating speed when a load is lowered.
b)
Brake is running too hot. This is caused by a complete
lack of, or insufficient circulation flow. To check the
circulation, observe the flow of oil from the circulation
return line of the winch (approx. 3.5 (US) gpm - 13 l/min)
when the winch is reversed.
c)
Control valve has poor metering characteristics.
d)
Damaged brake plates or divider plates.
e)
The over-running clutch, which connects the motor
shaft with the brake assembly, is damaged.
f)
Air mixed with hydraulic oil (foamy oil).
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a)
Insufficient hydraulic pressure (see HYDRAULIC
CIRCUIT for minimum pressure required for freespooling).
b)
If pressure is lost at freespool release port, freespool
piston O-ring, item 265, is damaged.
c)
Freespool piston may be seized due to contamination
in hydraulic fluid.
d)
Drum is turning or holding load. Drum must be stopped
with no load on wire rope while freespool option is used.
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a)
Oil leaks from the hydraulic motor flange and the motor
adaptor are caused by damaged O-ring seals.
b)
Oil leaks occurring between the cable drum flanges and
housings are caused by excessive pressure in the brake
housing. Excessive pressure will damage the oil seal which
separates the brake housing from the cable drum interior.
c)
If the breather relief on the end cover leaks, the seal
between the drum interior and the brake housing is
damaged and must be replaced. This condition is
caused by excessive pressure in the brake housing of
the winch, operation with the incorrect hydraulic fluid
during cold weather, or a restriction in the circulation
return line leading back to tank.
l
Brake will not hold.
Brake vibrates when lowering a load.
Refer to the SERVICE INSTRUCTIONS if it becomes necessary to disassemble the Model M12 winch with freespool.
Cable drum will not freespool.
Oil leaks.
256 REV.950401
