LST1H

Snap Action

• LST1H application field and working principle

LST1H is a type of snap action limit switch. It usually has a roller lever arm, plastic housing and screw terminal connection. Three basic elements make up a snap action limit switch, they are the electric contacts, actuator or plunger and a mechanism to return the plunger to the original position. This type of limit switch prevents equipment from reaching its maximum or minimum value limits. It is mainly used to detect the movement or position of machinery or materials, such as elevator doors, lifts, escalators and conveyor belts. The most common applications are electronic weighing scales and electric overload protection.

Generally speaking, this kind of limit switch is composed of a spring system, an actuator and a set of electric contact. The switch will change its state from "OFF" to "ON" when the actuator is pressed until it reaches the limit travel, then the spring force of the spring system will drive the actuator to reverse until it reaches the exact same spot then there is a "clicking sound", which is called the snap action phenomenon. This phenomenon is why it is called a "Snap Action" switch.

LST1H snap action limit switch has a insulated plastic housing which is used as a shield against dust and prevent short circuit. The actuator is one or two levers with a roller head, which is designed to reduce wear on the contacting surfaces and increase the life of the limit switch. This kind of limit switch is usually used for detect the positioning, operation positions and end-strokes of various machines.

LST1H has two types of working principles: mechanical and resistive. In mechanical working principle, the rotation of the actuator creates mechanical action, which will provide contact movement when the switch arrives at its limit positions. In resistive working principle, the pots are driven to rotate in order to provide electric contact when the switch reaches its limit positions. Both working principles will energise the contact (CLOSED) when the actuator is pressed until it reaches the limit travel, then the switch will be at the OPEN position.

In conclusion, LST1H is a snap action limit switch which is mainly used to detect the movement or position of machinery and materials, and it has two types of working principle, namely mechanical and resistive. It’s usually composed of electric contact, actuator or plunger and a mechanism to return the plunger to the original position. It’s usually enclosed in plastic housing to provide protection against dust and short circuits.