Duff-Norton EM1050-200 (TAP) User Manual

Page 6

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Limit Switch Adjustment

1. With translating tube unrestrained, run the actuator
toward the retracted position until the switch cam
actuates the switch.
2. Rotate the translating tube by hand to the desired
retracted position.
3. With the translating tube restrained against rotation,
run the actuator to the desired extended position.

4. Disconnect power. Remove motor cover.
On Potentiometer models only: remove two screws
holding the terminal block plate and pull plate and
potentiometer straight off, firmly holding limit switch
5. Raise the flap of the electrical insulator sheet to
expose the limit switch cams. Holding the cam gear to
prevent loading of the small gears, loosen the two
screws holding the top cam. Rotate the cam toward
the switch until the switch just clicks. Again holding the
gear, tighten the screws.
6. Restore power and operate actuator to check limit
switch settings.
7. If settings are correct, disconnect power and
reinstall motor cover.

1. Exercise care to avoid jamming the actuator.
2. With no load, some actuator drift is typical. If
precise setting is required, it must be done with the
expected operating load.
3. If problems are encountered setting the Retract
switch, check to see if motor is turning while the
translating tube is being twisted. If so, use a small
screwdriver to hold the end of the motor shaft while
twisting translating tube.
4. Rotating the translating tube will change the
settings of both switches by 1/6 inch per revolution of
the tube.

2-5. Potentiometer


1. Actuator limit switches must be set prior to
potentiometer installation.
2. The potentiometer is 5000 ohm single turn.
Resistance changes approximately 235 ohms per inch
for a 20:1 ratio actuator, or 117 ohms per inch for a
10:1 ratio.
3. Retract the actuator until the limit switch cuts it off.
Disconnect power.
4. Loosen 1/2" nut on potentiometer bushing. Press
potentiometer shaft into upper limit switch cam and
mount terminal block plate with two screws and
5. Use an ohmmeter to measure resistance between
potentiometer terminals




. Twist

potentiometer body to minimize resistance between
these terminals. Use a thin 1/2" end wrench to tighten
pot nut. Recheck for continuity between S and CW.
6. Terminal


is the potentiometer slider, with actuator

extension increasing the resistance between S and

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