16
TROUBLESHOOTING
If a hoist ever exhibits any sign of erratic operation, or load control diculties (load creeping or chattering) appropriate
troubleshooting tests and repairs should be performed immediately. Continued operation in this manner may result in
property damage, serious personal injury, or death.
A
The hoist will not lower the load or
not lower the load smoothly.
1. The problem could be a plugged
or loose pilot orice. The pilot ori-
ce is a small pipe plug with a hole
drilled through it, located behind
the pilot port tting on the brake
valve. If it becomes plugged, it will
prevent the pilot pressure, from the
manifold, from opening the brake
valve. If it becomes loose, it will al-
low an unregulated amount of oil
in to operate the brake valve which
cause erratic brake valve opera-
tion.
Remove the pilot hose and tting from
the brake valve, then use a 5/32-inch
Allen wrench to remove the pilot ori-
ce. The diameter of the orice is ap-
proximately .020 inch. Clean and in-
stall the pilot orice tightly in the brake
valve.
2. The friction brake may not be re-
leasing as a result of a defective
brake cylinder seal.
NOTE: If the brake cylinder seal
is defective you will usually nd oil
leaking from the hoist vent plug.
Check brake cylinder seal as follows:
A. Disconnect the swivel tee from
the brake release port. Connect a
hand pump with accurate 0–2,000
PSI gauge and shut-o valve to
the –4 JIC tting in the brake re-
lease port.
B. Apply 1,000 PSI to the brake.
Close shut-o valve and let stand
for ve minutes.
C. If there is any loss of pressure in
ve minutes, the brake cylinder
should be disassembled for in-
spection of the sealing surfaces
and replacement of the seals. Re-
fer to Motor Support-Brake Cylin-
der Service section of manual.
3. Friction brake will not release as a
result of damaged brake discs.
Disassemble brake to inspect brake
discs. Check stack-up height as de-
scribed in Motor Support-Brake Cylin-
der Service section.
TROUBLE PROBABLE CAUSE REMEDY
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