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setting limit switch pdf Setting GE Rotary Limit Switches
Adjust Limit Drive the winch to the desired end of travel. Re-verify cam stack rotation (when the winch travels up, does the
cam stack rotate clockwise or counterclockwise). Determine
which side of the desired switch the limit cam must strike (i.e.,
if cam stack rotates clockwise when the winch travels down, and
you are setting a down limit, the cam must actuate the down limit
while moving in a clockwise direction). Again use an insulated screwdriver! Loosen cam stack clamping screws (1/2 turn). Locate the cam adjusting pinion for the desired limit by
referring to the switch labels and the indicating arrows on the
insulation shields. Depress the cam adjusting pinion with an insulated screwdriver
until the gears mesh. Rotate the pinion to adjust the limit cam lobe to a position where
the selected limit switch is just actuated (audible click). Note
that the pinion is a gear it must turn counterclockwise (CCW)
to rotate limit cam clockwise (CW), and the pinion turns CW to
rotate limit cam CCW. Once the limit cam is at the proper place, tighten the cam stack
clamping screws.
Test Limit Drive winch away from limit until limit is cleared (use over travel
bypass switch to move winch off over travel limit). Drive winch toward limit until limit stops motion. Assess stopping position (measurement vs. target). Drive winch off limit (use over travel bypass switch to move winch
off over travel limit).
Refine Limit Adjustment Repeat the Adjust Limit procedure, as outlined. Move cam lobe closer to switch to make switch trip sooner
(decrease travel distance). Move cam lobe fur ther from switch to make switch trip later
(increase travel distance). Make sure to tighten cam stack clamping screws after each
adjustment! Retest limit adjustment until winch stops at desired position.
Adjust Remaining Limits Once over travel limit is set, set normal limit at same end
of travel. Check to ensure that there is sufficient distance between normal
limit and over travel limit if the winch strikes both limits before
stopping, increase the distance between the limit by moving the
normal limit to stop the load sooner. Once all limits are set, check that cam stack clamping screws
are tightened, then replace the limit switch cover. Once the limit switch cover is in place and tightened down,
re-test the normal limits to ensure they have not been shifted by
the cover.
Special Considerations The limit switch cover has a socket which engages the top of the
cam stack center post. On rare occasions, the position of the
cover may affect the limit positions. Make sure that the cover is
securely fastened in place, and that the limits have been re-
tested after the cover is on. Occasionally a limit switch cam will not actuate an operating
switch. This condition generally indicates that the operating
switch has been shifted within the limit switch assembly,
generally during field wiring. If this occurs, determine which
operating switch is at fault. Loosen the two mounting screws that
hold the switch in place, move the operating switch as close to
the cam stack as possible, then re-tighten the mounting screws.
Design, Manufacture and Installation of Theatrical Equipment Worldwide
© 2005 J.R. CLANCY, INC.
1-800-836-1885
www.jrclancy.com
Establish Rotation Remove limit switch cover. Drive winch in UP direction note direction of cam stack rotation. Mark switch cover or cam stack to record cam stack rotation. Use an insulated screwdriver to adjust the limit avoid
contacting screw terminals on operating switches while winch
system is on.
Determine Travel Determine where load must stop to avoid damage/
misalignment set over travel to stop shor t of this point. Determine what range of normal travel for load must be set
normal limits to stop load at these points. For each end of travel, set over travel limit first, then set end-of-
travel limit. Make sure that the operator can clearly see the entire load for
its entire travel, or that spotters are in place to obser ve and
clearly communicate with the operator.
Cam
Clamping
Screws
Cam Stack
Cam
Adjusting
Pinions
Cam Lobe
Marker
Operating
Switches
Operating
Switch
Mounting
Screws
UP LIMIT
DOWN LIMIT
UP OVERTRA
VEL
DOWN OVERTRAVEL
Shaft Extensions
Figure 1. GE CR115E Geared Rotar y Limit Switch