Travel switch, a type of position switch (also known as limit switch), is a commonly used small current main electrical appliances. Using the collision of the moving parts of the production machine to make the contact move to realize the switch on or off the control circuit, to achieve a certain control purpose. Usually, this kind of switch is used to limit the position or stroke of mechanical movement, so that the moving machine can automatically stop, reverse movement, variable speed movement or automatic round trip movement according to a certain position or stroke.