What is the technical principle of different limit switches?

1、Mechanical limit switch:
The mechanical micro limit switch is an electromechanical device that detects the position of the target through direct physical contact with the target. They do not require power to operate and can handle large current loads. Because mechanical switches use dry contacts, they are not polarity or voltage sensitive and are protected from many electrical defects, such as electrical noise, RF interference, leakage current, and voltage drop. These switches often include multiple moving parts that may require maintenance (lever arms, buttons, body, base, head, contacts, terminals, etc.).

Because Votto mechanical limit switches operate in physical contact with the target, their repeatability can be poor. Physical contact causes wear on the lever arm and even the target itself. In addition, there are unsealed openings with poor protection against moisture, dust and corrosion. As a result of this problem, sealed contacts and hazardous area certification typically increase in cost significantly.

2、Spring limit switch：
The spring limit switch is an electromechanical device that detects the position of the magnetic target by attracting the magnetic field of the target. Inside the switch are two small metal pins, airtight sealed in a glass tube. This is called a “reed element”.

The reed element is magnetically sensitive and activates when a magnetic target passes close by. Spring limit switches have almost all the advantages of mechanical switches and avoid wear and tear problems by operating without relying on physical contact from the target. With a spring limit switch, normal black metal targets cannot be used; You need a magnetic target. The reed element is fragile, the glass tube is destructible, and the small metal prongs are subject to fatigue from bending, causing the reed switch to become unreliable.

Due to the low contact pressure, the application of high vibration can lead to contact chatter and false signals from the reed.