Troubleshooting - BRADEN CH280 Installation Maintenance And Service Manual

If a hoist ever exhibits any sign of erratic operation, or load control difficulties (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.
TROUBLE
A
The hoist will not lower the load or
not lower the load smoothly.

TROUBLESHOOTING

PROBABLE CAUSE
1. The problem could be a plugged
or loose pilot orifice. The pilot ori-
fice is a small pipe plug with a hole
drilled through it, located behind
the pilot port fitting 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.
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 find oil
leaking from the hoist vent plug.
3. Friction brake will not release as a
result of damaged brake discs.
16
REMEDY
Remove the pilot hose and fitting from
the brake valve, then use a 5/32-inch
Allen wrench to remove the pilot ori-
fice. The diameter of the orifice is ap-
proximately .020 inch. Clean and in-
stall the pilot orifice tightly in the brake
valve.
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-off valve to
the –4 JIC fitting in the brake re-
lease port.
B. Apply 1,000 PSI to the brake.
Close shut-off valve and let stand
for five minutes.
C. If there is any loss of pressure in
five 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.
Disassemble brake to inspect brake
discs. Check stack-up height as de-
scribed in Motor Support-Brake Cylin-
der Service section.