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NOTE: Brake test to be performed with no load on the
hoist. The weight of the wire rope, hook block and over-
haul ball or hook weights are acceptable.
NOTE: If the hoist is equipped with a ratchet and pawl
mechanism, the pawl lever
MUST
be disengaged from
the ratchet wheel by disconnecting the cylinder and
rotating the pawl lever
clear
of the drum and ratchet
wheel.
NOTE: AB (aux. brake) Hoists now include a second
needle valve like that used on the API designated hoists
for emergency brake release, which can be used to iso-
late the auxiliary brake. Some early AB hoists did not
include the second needle valve.
1. Remove the lock wire on the needle valve handle in
the auxiliary brake circuit and close the valve tightly.
Remove the cap from the tee in the auxiliary brake
release circuit.
Note: For early units without the needle valve,
remove the brake release hose from the fitting on
the auxiliary brake housing. Plug the end of the
hose, and leave the brake release port fitting open to
atmosphere.
2. With the hydraulic power unit (HPU) running, move
the directional control valve handle slowly to the full
open, hoisting position.
3. Increase the engine speed, if necessary, to bring the
system pressure up to the relief valve setting. The
hoist drum should remain stationary.
4. This procedure utilizes the hoist hydraulic motor to
test the brake's ability to resist at least 100% of the
hoist rated capacity.
Once the brake test is completed, be sure to reinstall
the cap on the tee, fully open the needle valve and
replace the lock wire in the handle, if so equipped, or
reattach the hose to the brake release port fitting.
If the drum rotates or slips during the test, the hoist
should be disassembled and the brake should be exam-
ined for wear or damage. In addition, the brake springs
should be measured for the correct free length.
Replace any parts exhibiting excessive wear, and any
spring whose length is outside the dimensions defined
in the manual. Reassemble the brake and hoist and
repeat the test.
AUXILIARY BRAKE TEST PROCEDURE
