Compact Limit Switch (CLS)

Patent Pending

Every motorized Worm Gear Screw Jack 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 ActionJac™ Compact Limit Switch (CLS) senses extension shaft rotation and provides switch contact closures that can be used to control motors.

The CLS is an economical way to detect travel limits and prevent over travel of the Worm Gear Screw Jacks. The Single Pole Double Throw (SPDT) limit switches are useful for limiting the maximum and minimum extension.

The CLS is wired as a normally closed circuit, but can easily be wired as a normally open circuit. The CLS is provided with a standard terminal block for ease of set up. The CLS limit switches are adjustable in the field with the removal of the easily accessible enclosure cover.

The CLS is designed to accommodate a variety of standard options, which include a Hall Effect, Potentiometer, and Reed Switch. The potentiometer version is used to provide an analog signal for sensing jack position. The Hall Effect Sensor and Reed Switch are used to provide a pulse signal to indicate jack travel. The CLS has been designed to meet NEMA 4 standards for dust and water tightness. The CLS can be provided with a variety of gear ratios to accommodate virtually any travel.

How To Order A Compact Limit Switch

Insert the correct designation in the ActionJac™ Worm Gear Screw Jack reference number (see page 31 and 69 in our Worm Gear Screw Jacks Catalog for more information on jack reference numbers).


(See Image 3 in Figure 1 Below)

Examples of compact limit switch designations:

CLSS-8 - Standard CLS w. SPDT limit switches only, Position #8
CLSR-4 - Standard CLS w. SPDT limit switches, Reed Switch, Position #4
CLSH-3 - Standard CLS w. SPDT limit switches, Hall Effect Sensor, Position #3
CLSP-1 - Standard CLS w. SPDT limit switches, Potentiometer, Position #1

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 jack. If you are ordering a replacement switch assembly, complete information on the jack is required.


  • Light weight
  • Twelve gear ratios to accommodate most travels
  • Contains two limit switches
  • Simple travel adjustment design
  • Eight different mounting positions
  • Available on 2 ton through 20 ton
  • Optional Reed Switch, Hall Effect Sensor, or Potentiometer
  • Internal Limit Switch temperature range from -20° to 150°F
  • Feedback option available

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

CAUTION: Limit switches are not set at the factory. Switches must be set during installation and prior to use. The limit switch assembly will be permanently damaged if allowed to over travel. CLS is supplied with a plugged access hole. For a water-tight connection, water-tight connector and sealant should be used.

The Compact Limit Switch is not intended to be used as a safety device.

Product Code Switch Type Max Torque Rating (in-lb)
CLSR SPDT Reed Switch
CLSH SPDT Hall Effect Sensor
CLSP SPDT Potentiometer

Circuits H
2-BSJ & MSJ 7.08
2.5-BSJ & MSJ 7.14
3-BSJ 7.08
5-BSJ & MSJ 7.90
10, 15-BSJ & MSJ 8.40
20-BSJ & MSJ 8.85


(See Image 4 in Figure 1 Below)

Electrical Ratings


DC Current - 125 Volts SPDT, .50 amps
AC Current - 250 Volts SPDT, 11 amps

10-Turn Potentiometer

10,000 OHM, 2 Watt

NOTE: While the 10-turn potentiometer is rated for 10,000 Ohms, as implemented in the compact limit switch assembly, it can not and should not operate over its full range. Minimum and maximum resistance values can not 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

Please see (See Image 5 in Figure 1 Below)

Figure 1