The forks in machinery are generally divided into fork claws, fork shafts and fork handle seats. It is mainly to slide the sliding gear and change its position on the gear shaft, it can move up and down or left and right to achieve different speeds. Or it is the control of the clutch in mechanical products, such as the structure of the end face coupling teeth, the structure of the inner and outer teeth, all need to use a fork to control a part of it to achieve the combination and separation. Another is that the control of electrical appliances in mechanical products also requires a fork to achieve the closing and opening of the switch. Generally, there is a card switch on each side of the electrical box. .