Limit Switches Protection

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Limit Switches

A Limit Switch is designed to safeguard an internal basic switch from external factors like force, liquids, and dust. They come in various shapes, including Horizontal, Vertical, and Multiple types, typically consisting of five components.

What is a Limit Switch?

Limit Switches encase basic switches for protection against external forces and environmental factors. They suit applications needing mechanical strength and durability. Shapes include horizontal, vertical, and multiple types.

Typical components include five parts.

Structures and principles

Drive Mechanism of Limit Switch 

The drive mechanism in Limit Switches is crucial for sealing and performance. It’s categorized into three types for different applications:

(1) Plunger 

There are two plunger types, A and B, based on sealing. Type A employs an internal seal, resisting debris but potentially accumulating sand. In contrast, Type B offers superior sealing but may be vulnerable to damage from hot cutting debris.

The choice between Type A and Type B depends on the intended usage environment.

In plunger drive, the plunger’s movement compresses air, which can result in slow resetting. To prevent this issue, it is advisable to limit plunger compression to 20% or less of the total air pressure. Additionally, an OT absorption mechanism, utilizing a spring, aids in absorbing any remaining plunger movement and effectively controls the switch. This mechanism significantly extends the service life of the Limit Switch.

(2) Hinge Lever 

The lever ratio amplifies plunger movement at the lever end (i.e., roller), eliminating the need for an absorption mechanism.

(3) Roller Lever 

The WL structure is a common example. Other designs include plunger acting as the reset plunger and employing a coil spring for reset force with a cam moving the auxiliary plunger.

Switch Component Materials

The main parts of the Switch are formed from the following materials.


Movable springs and armatures 

Cases and Covers 

Switch boxes 

Rubber seats 

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