STRUCTURALS 5540F/YB5515 SERVICE MANUAL
11-50
Troubleshooting
.
Trouble Possible Cause Remedy
A - The winch will not lower the load or
not lower the load smoothly.
1. The friction brake may not be
releasing as a result of a defective
brake cylinder seal.
NOTE: If the brake cylinder seal is
defective leaking will occur
from the winch vent plug.
2. Friction brake will not release as a
result of damaged brake disc.
1. 1.Check brake cylinder seal as
follows:
a. Disconnect the swivel tee
from the brake release
port.Connect a hand pump
with an accurate 0-2000 psi
(0-13 790 kPa) pressure
gauge and shut-off valve to
fitting in the brake release
port.
a. Apply 1000 psi (6895 kPa) to
the brake. Close the shutoff
valve and let stand for five (5)
minutes.
a. If there is any loss of pressure
in five (5) minutes, the brake
cylinder should be
disassembled for inspection
of sealing surfaces and
replacement of the seals.
Refer to “Motor Support-
Brake Cylinder Service”.
2. Disassemble the brake to inspect
brake discs. Check stack-up
height as described in “Motor
Support-Brake Cylinder Service.”
B - Oil leaks from vent plug.
1. Same as A2.
2. Motor seal my be defective as a
result of high system back
pressure.
1. Same as A2.
2. System back pressure must not
exceed 500 psi (3448 kPa).
Inspect hydraulic system for a
restriction in the return line from
the main control valve to the
hydraulic tank.
Oil analysis may indicate
contamination has worn the motor
shaft and seal. Install a new motor
seal.
Reference Only
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