15
A
The hoist will not lower the load or
not lower the load smoothly.
1. Remove pilot hose and tting from
brake valve, then use a 5/32 inch Al-
len wrench to remove pilot orice.
The diameter of the orice is approxi-
mately .020 inches. Clean and install
pilot orice tightly in the brake valve.
2. Check brake cylinder seal as fol-
lows:
a. Disconnect the swivel tee from the
brake release port. Connect a hand
pump with accurate 0-2000 PSI
gauge and shut-o valve to the –4
JIC tting in the brake release port.
b. Apply 1000 PSI (68.9 bar) to the
brake. Close shut-o valve and let
stand for ve (5) minutes.
c. If there is any loss of pressure in
ve (5) minutes, the brake cylinder
should be disassembled for inspec-
tion of the sealing surfaces and re-
placement of the seals. Refer to “Mo-
tor Support-Brake Cylinder Service.”
3. Disassemble brake to inspect
brake discs. Check stack-up height
as described in “Motor Support-
Brake Cylinder Service.”
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 allow an un-
regulated amount of oil in to operate
the brake valve which cause erratic
brake valve operation.
2. The friction brake may not be re-
leasing as a result of a defective
brake cylinder seal.
NOTE: A defective brake cylinder
seal will cause oil to leak from the
vent plug.
3. Friction brake will not release as
a result of damaged brake discs.
TROUBLE
PROBABLE CAUSE
REMEDY
TROUBLESHOOTING
If a hoist ever exhibits any sign of erratic operation, or load control diculties (i.e. 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.
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