There are many applications for the limit switch, and many appliances have it. So what can such a simple switch do? It mainly plays the role of chain protection. The most common example is its application in washing machines and recorders (video recorders).
In the process of dehydration (drying) of the washing machine, the speed is very high. If someone accidentally opens the door or cover of the washing machine at this time, and then puts his hand in, it is easy to cause injury. An electric contact is installed on the door or cover. Once someone opens the door or cover of the washing machine, the motor is automatically powered off, and even by mechanical means, the door or cover "brake" as soon as it is opened, forcibly turning. Stop the parts to avoid personal injury.
In recorders and video recorders, we often use fast forward or rewind, and the tape rotates rapidly, but it stops automatically when it reaches the end of the tape. Here the travel switch once again played a role, but this time it was not caused by a collision but caused by a sudden increase in the tension of the tape.
The limit switch is mainly used to convert the mechanical displacement into an electric signal, so that the running state of the motor can be changed, thereby controlling the mechanical action or used as a program control.
The real use of the limit switch is in industry, where it cooperates with other equipment to form more complex automation equipment.
There are many such travel switches on the machine tool, which are used to control the movement of the workpiece or the stroke of the automatic feed to avoid collision accidents. Sometimes the travel switch is used to automatically switch the controlled object between two specified positions, so as to obtain continuous reciprocating motion. For example, the trolley that automatically transports the material reaches the end point, touches the travel switch, turns on the turning mechanism, and dumps the material in the trolley and returns to the starting point. After reaching the starting point, the stroke switch of the starting point was touched, the circuit of the loading mechanism was switched on, and automatic loading was started. If you go on like this, it will become a set of automatic production line, without human management, working around the clock, saving human physical labor.