Types of Limit Switches and Their Applications – Full Guide!

Whether it be the industrial, construction, agriculture, commercial, or transportation industry, limit switches have become an integral part of the sensing and control community. There are perhaps trillions of limit switches in use at this very moment in various types of industrial equipment, agriculture or construction machinery, and control systems around the globe. Below I explained all the types of limit switches.

Limit Switch Types

The types of limit switches are:

1.Roller lever

Levers and roller levers actuate radially. They rotate on an axis. Roller levers are tipped with a roller to lessen the friction and the force required to activate the lever. The lever spring returns to neutral when the force is removed. Roller levers are the most popular option for operators.

2.Adjustable roller lever

An adjustable roller lever is similar to a standard roller lever. The length of the lever is adjustable from a few millimeters to up to 5 centimeters. The rollers are also available in various diameters.

3.Rounded plunger

Plunger heads come in many varieties and sizes. Plungers are actuated by a perpendicular force applied directly to the end of the plunger.

4.Roller plunger

When a plunger switch is needed, but the force will not be applied directly at a 90º angle, a roller plunger can be used. The roller converts some of the non-perpendicular force into perpendicular force that can actuate the plunger.

5.Rod lever

Rod levers are also actuated radially like levers. They are thin and much longer. Adjustable rods can be as long as 10 or more centimeters.

6.Flexible rod

A flexible rod is similar to a rod lever in its length and appearance. However, unlike levers that actuate only in one plane, flex rods activate in 360º

7.Cable pull

These switches are tipped with a lanyard and can be attached to a cable. Pulling or tightening the cable draws out the springloaded lever, which activates the switch.

8.Rotative Axis

These switches can be installed onto an axis (i.e., a door hinge) so that when the hinge or axis turns, the switch actuates.

Applications of Limit Switches

Limit switches have wide usage areas such as:

• Machine tools: Metal fabrication equipment, presses, transfer lines, and special machinery.
• Material handling equipment: Conveyors, elevators, cranes, and hoists.
• Packaging machinery and process equipment.
• Textile machinery.
• Construction machinery and equipment, vehicles, and lift trucks.
• Control cabinets.
• Garage doors.

Application example:

The figure below shows the control circuit for starting and stopping a motor in the forward and reverse directions with two limit switches providing overtravel protection. The operation of the circuit can be summarized as follows:
• Pressing the momentary forward push button completes the circuit for the F coil, closing the normally
open maintaining contact, and sealing in the circuit for the forward starter coil.
• At the same instant, the normally closed interlock contact F opens to prevent the reverse direction of
the motor.
• To reverse the motor direction the operator must first press the stop button to de-energize the F coil
and then press the reverse push button.
• If the overtravel position should be reached in either the forward or reverse direction, respective N.C.
the limit switch will open to prevent any further travel in that direction.
• The forward direction is also interlocked with a normally closed R contact.