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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
pocket.
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.
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 (see TYPICAL HYDRAULIC
CIRCUIT) 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).
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 secondary housing from
the cable drum interior.
c) If the breather relief on the end cover leaks, the seal
between the drum interior and the secondary 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.
TROUBLE SHOOTING CONTINUED
PROBABLE CAUSEFAILURE
Brake vibrates when lowering a load.
Brake will not hold.
Oil leaks.
Refer to the SERVICE INSTRUCTIONS if it becomes necessary to disassemble the Model M75 winch.
354 REV.030819
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