Electric Cylinders Rotary Limit Switch

Every motorized Electric Cylinder must be controlled so that power to the motor is turned off and the brake engaged before the limits of mechanical travel are reached.

The rotary limit switch senses extension shaft rotation and provides switch contact closures that can be used to control motors.

This sturdy, durable assembly is available with two or four circuits or two circuits and a potentiometer. Each circuit has a separate rotating cam that actuates a high quality switch. The switch actuation may be individually and infinitely adjusted anywhere within the travel of the cylinder.

These assemblies contain gear reducers with ratios that vary according to the model and travel of the electric cylinders. Nook selects ratios that result in maximum cam rotation for best accuracy, repeatability and minimum hysteresis. In most cases, with full travel of the actuator, the cam will rotate 3/8 to 7/8 of a revolution to actuate a switch. In the event that the cam continues to rotate, the switch returns to its original state after approximately 25° of rotation, with no damage to the limit switch assembly.

A 2-circuit switch assembly is useful for limiting the maximum and minimum extension. A 4-circuit assembly gives the possibility of additional signals for other user purposes. The potentiometer version is used to provide an analog signal for sensing cylinder position.

Single Pole Double Throw (SPDT) switches are standard and Double Pole Double Throw (DPDT) switches are optional. These assemblies are dust protected and meet NEMA 4 and 5 standards for oil and water tightness. A rotary limit switch assembly is mounted to the extension shaft side of the Worm Gear Screw Cylinder opposite the motor.

A rotary limit switch is available for Electric Cylinder Series DD-25 and RAD-25 and larger. Most cylinder models have close and extended mounts for the switches to provide clearance around the switch housing. See the charts below for dimensions.

Switches are factory installed to assure proper assembly in the correct orientation for the specified mounting position.

CAUTION: Limit switches are not adjusted at the factory. Switches should be set after installation.

How To Order A Rotary Limit Switch

    SPECIFY:
  • Product code (see table below)
  • Mounting position
  • Close or extended mount (C or E)

Insert the correct designation in the Electric Cylinder reference number (see page 37 or 57).

Please refer to Image 2 in Figure 1 Below for example

Examples of rotary limit switch designations:
2CA-4C - 2 circuit, SPDT, position 4, close mount
4CE-1E - 4 circuit, DPDT, position 1, extended mount
C = Close mount on
E = Extended mount please see Image 3-4 in Figure 1 Below

>IMPORTANT: These designation numbers are not complete part numbers. These assemblies contain gear reducers with ratios that vary according to the model and travel of the cylinder. If you are ordering a replacement switch assembly, complete information on the electric cylinder is required.

Product Code Number of Circuits Switch Type Potentiometer
2CA 2 SPDT NO
2CC 2 DPDT NO
4CA 4 SPDT NO
4CE 4 DPDT NO
PTA 2 SPDT YES
PTC 2 DPDT YES

Explosion Proof model also available. Contact Nook Engineering for more information.

  DIMENSIONS
CIRCUITS A B C D E F
2 CIRCUIT 2.46 5.25 6.24 7.62 34-NPT 3.25
4 CIRCUIT OR 2 CIRCUIT WITH POTENTIOMETER 2.46 5.25 8.24 9.62 1-NPT 3.88

SERIES DIMENSION H CLOSE MOUNT DIMENSION H EXT. MOUNT
DD & RAD 25 2.75 3.56
DD & RAD 30 2.75 3.56
DD & RAD 50 3.56 4.56
DD & RAD 100 3.88 5.56
DD & RAD 200 4.41 5.81

Electrical Ratings:

Switches:

DC Current - 115 Volts SPDT, .50 amps
DPDT, .80 amps
AC Current - 115 Volts SPDT, 15 amps
DPDT, 10 amps

10-Turn Potentiometer:

0-500 OHM, 2 Watt

NOTE: While the 10-turn potentiometer is rated for 0-500 Ohms, as implemented in the rotary limit switch assembly, it cannot and should not operate over its full range. Minimum and maximum resistance values cannot be known until the unit is installed and final travel limit adjustments have been made, therefore, the device connected to the potentiometer should include provisions for trimming to compensate for these values.

Wiring Diagrams

Image 4 in Figure 1 Below

Figure 1