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Figure 7-1. Geared Rotary Limit Switch Adjustment
(Early Model Hoists)
11991
7-4. GEARED ROTARY LIMIT SWITCH ADJUSTMENT.
The geared rotary type limit switch is optional equipment and
when furnished is located at the motor end of the hoist.
a. This limit switch consists of two adjustable cams driven
thru gear reduction by a worm gear shaft which flexibly
couples to end of drum shaft. Each cam operates the
contacts of separate switches; one for hoisting circuit and
one for lowering circuit. The switch assembly must be
wired in accordance with appropriate wiring diagram which
is shipped with the hoist. Adjustment of the rotary limit
switch is accomplished as follows: (Refer to Figure 7-1.)
(1) Remove four cover screws and lift off enclosure cover.
(2) Operate hoist to raise lower block to upper limit of
desired travel. Allow about 2" for drift.
(3) Loosen the two cam clamping screws on top of cam
assembly one half turn each.
(4) Locate cam adjusting pinion “A” (upper) by referring
to the indicating arrow on insulation shield. Depress
this screw with a screwdriver until pinion teeth mesh
with gear teeth on top cam. Rotate cam in direction
cam turns when hoisting by turning screwdriver until
cam operates switch. White marker on gear teeth is
directly over nylon roller that trips switch. When top
operating cam has been adjusted so the roller has
tripped switch, adjustment of upper limit is complete.
(5) Operate hoist and run lower block to lower limit of
desired travel. Allow approximately 6" for drift. Make
certain that at the lowest point of hook travel a
minimum of 1 turn of wire rope remains on rope drum.
(6) Locate cam adjusting pinion “B” (lower) by referring
to the indicating arrow on insulation shield. Depress
this screw with a screwdriver until pinion teeth mesh
with gear teeth on lower cam. Rotate cam in direction
cam turns when lowering by turning screwdriver until
cam operates switch. White marker on gear teeth of
lower cam will be directly over nylon roller that trips
switch and adjustment is complete.
Figure 7-2. Screw-Type Limit Switch Adjustment
1. Remove four screws and lift off switch cover.
2. Loosen locking plate screws. Slide locking plate away
from adjustment discs.
3. Turn proper adjustment disc (right for up, left for down)
toward switch to reduce hook travel or away from switch
to increase hook travel.
4. Slide locking plate back into position ensuring slots on
adjustment discs are fully engaged, tighten locking plate
screws to 4 in-lbs.
5. Replace cover.
(7) Retighten cam clamping screws, fold down insulating
shields and replace cover.
b. This limit switch has a rotary screw driven by a
gear reduction which is coupled to the end of the drum
shaft. Adjustment discs operate the contacts of separate
switches; one for the hoisting circuit and one for the
lowering circuit. The switch assembly must be wired in
accordance with the appropriate wiring diagram, which is
shipped with the hoist. Instructions for adjusting limit switch
are inside switch cover and are repeated below (see
Figure 7-2).
Check limit switch operation carefully, without load,
before placing hoist in service. If misadjusted,
SEVERE DAMAGE AND/OR A DROPPED LOAD
COULD RESULT. Allow 6" for hook drift in both
directions. Never allow less than 1 complete wrap of
rope on drum with hook in lowest position.
WARNING
Provide a light film of NLGI No. 2 grease on gear of both limit
switches.
7-5. OVERLOAD CLUTCH ADJUSTMENT AND TESTING.
a. When hoist is equipped with an overload clutch, minor
clutch adjustments can be made with your hoist
suspended. Clutch adjustment shall be supervised by an
authorized person familiar with the hoist and the purpose
of the adjustment and test. (See Paragraph 5-6.e for
disassembly, inspection and readjustment.) To test clutch
operation and make minor adjustments, proceed as
follows:
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