HOISTS 777 SERVICE MANUAL
5-16 Published 10-01-2012, Control # 045-08
DRUM PAWL ADJUSTMENT
The drum pawls are positive locking devices which, when
engaged, prevent the load drums from turning in the lowering
direction.
The drum pawls are engaged and disengaged electrically by
motor driven screw-type actuators. A limit switch inside both
ends of each actuator turns off the motor when the actuator
is fully extended or retracted.
The drum pawls are adjusted at the factory and should not
need further adjustment during the service life of the
actuators. Adjustment is necessary when a new actuator is
installed.
Actuator Removal
See Figure 5-13 for following procedure.
1. Fully disengage corresponding pawl and stop engine.
• Front drum actuator will extend.
• Rear drum actuator will retract.
NOTE: It may be necessary to hoist slightly before pawl
will fully disengage.
2. Disconnect electrical cord from actuator being removed.
3. Back out adjusting screw until leaf spring is fully relaxed.
4. Remove pins holding actuator to mounting lug and
bracket.
5. If necessary, loosen mounting bracket nuts to loosen
actuator connecting pins.
6. Remove actuator.
Actuator Installation and Adjustment
See Figure 5-13 for following procedure.
1. Move cab power switch to ON position and engine run-
stop switch to RUN position. Do not start engine.
2. If necessary, move corresponding pawl switch to
DISENGAGED position.
3. Connect electrical cord to actuator:
• Front drum actuator will extend.
• Rear drum actuator will retract.
4. Pin actuator to mounting bracket and lug.
5. Loosen mounting bracket nuts.
6. Slide mounting bracket rearward until dimension
between pawl and ratchet teeth is 7/8 inch (22 mm) as
shown in View B or D or bracket bottoms out in slots,
whichever occurs first.
7. Tighten nuts to hold mounting bracket in position.
8. Turn adjusting screw in until dimension between pawl
and ratchet teeth is 3/8 in. (9 mm) as shown in View A or
View C.
9. Securely tighten jam nut to lock adjusting screw.
10. Operate pawl to make sure that internal limit switches
stop actuator motor when actuator is fully extended and
fully retracted and that pawl fully engages and
disengages ratchet.
DANGER
Flying Part Hazard!
Leaf springs are preloaded. Do not proceed to step 4 until
step 3 is performed. Parts will fly apart with sudden and
dangerous force if preload is not relieved.
WARNING
Pinch Point Hazard!
Actuator rod will either extend or retract when step 3 is
performed, To prevent crushing injury to hands, keep
actuator clear of all other parts while performing step 3.
CAUTION
Actuator must be free to fully extend and retract. Motor
will overheat if actuator stroke is restricted in either
direction.
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