13
3. Friction brake will not release as a
result of damaged brake discs.
3. Disassemble brake to inspect brake
discs. Check stack-up height as de-
scribed in “Motor Support — Brake
Cylinder Service.”
A
The hoist will not lower the load or
does not lower the load smoothly.
TROUBLE
PROBABLE CAUSE
REMEDY
B
Oil leaks from vent plug.
1. Same as PROBABLE CAUSE A2.
2. Motor seal may be defective as a
result of high system back pressure or
contaminated oil.
a. Vent positioned below oil level.
b. Oil expansion as a result of overheat-
ing.
1. Same as REMEDY A2.
2. System back pressure must not exceed
150 PSI (1,035 kPa). Inspect hydraulic
system for a restriction in the return line
from the control valve to the reservoir.
Be sure control valve and plumbing is
properly sized to hoist motor.
3. Oil analysis may indicate contami-
nation has worn motor shaft and seal.
Thoroughly flush entire hydraulic sys-
tem and install new filters and oil. In-
stall new motor seal.
C
The brake will not hold a load with the
control lever in neutral.
1. Excessive system back pressure acting
on the brake-release port.
2. Friction brake will not hold load due
to worn or damaged brake discs.
3. Brake clutch is slipping.
1. Same as REMEDY B2.
2. Same as REMEDY A3.
3. Brake Clutch Slipping:
a. Improper planetary gear oil may
cause the brake clutch to slip. Drain old
gear oil and flush hoist with solvent.
Thoroughly drain solvent and refill hoist
with recommended planetary gear oil
listed in “Preventive Maintenance.”
b. Brake clutch may be damaged or
worn. Disassemble and inspect brake
clutch as described in “Brake Clutch
Service.”
