Manitowoc Published 05-03-17, Control # 228-03 5-7
16000 SERVICE/MAINTENANCE MANUAL HOISTS
Maintenance
Inspect and test the block-up limits weekly or every 40 hours
of operation, whichever comes first, using the following
procedure:
1. Lower the boom and jib onto blocking at the ground level
and carefully inspect the following items:
a. Inspect each limit switch lever and actuating lever
for freedom of movement. If movement is not free,
apply a half shot of grease to the fitting on the
actuating lever. Wipe away any excess grease.
b. Inspect each weight for freedom of movement on
the load line.
c. Inspect each weight, chain, shackle and connecting
pin for excessive or abnormal wear. Make sure all
cotter pins or shackles are installed and spread.
d. Inspect the entire length of each electric cable for
damage.
e. Make sure electrical cables are clear of all moving
parts on the boom and jib and that cables are
securely fastened to the boom and jib with nylon
straps.
f. Check that all plugs are securely fastened.
2. Test the block-up limits for proper operation using either
of the following methods:
a. To test with the boom lowered, manually lift each
weight, one at a time, while the engine is running.
The load drum should not operate in the hoist
direction and the boom/mast hoist should not
operate in the lower direction.
b. To test with the boom raised, slowly hoist each load
block and weight ball, one at a time, against weight.
When the chain goes slack, the corresponding load
drum should stop hoisting and the boom/mast hoist
should not operate in the lower direction.
Adjustment
See Figure 5-5 for the following procedure.
Lower the boom onto blocking at the ground level and adjust
each limit switch using the following procedure:
1. Adjust the spring tension so there is enough force to lift
the weight of the chain and rotate the actuating lever
when the weight is lifted.
2. Loosen the setscrew in the limit switch lever so the lever
is free to rotate.
3. Manually lift the weight to allow the actuating lever to
rotate upward.
4. Hold the actuating lever at the position shown in
Figure 5-5
.
5. Hold the roller on the limit switch lever against the
actuating lever while performing step 6.
6. Turn the limit switch shaft counterclockwise (for right
hand) or clockwise (for left hand) only enough for the
limit switch to click into the open position and hold there.
Then securely tighten the setscrew in the limit switch
lever.
7. Test the limit switch for proper operation (see the
Maintenance topic for details). Repeat adjustment steps
until the limit switch operates properly.
CAUTION
Avoid Machinery Damage!
To prevent two-blocking from occurring, do not operate
the crane until all causes of improper operation and all
hazardous conditions have been found and corrected.
CAUTION
Avoid Sheave Damage!
Use extreme care when testing block-up limits when the
boom is raised. If a block-up limit fails to stop the load,
immediately stop the load by moving the drum control
handle to off. If the load is not stopped, two-blocking may
occur.
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