The screw jack is the representative of a mechanical jack, and the core part of the screw jack must be the screw, because the entire lifting process of the jack relies on the transmission part to spiral drive around the screw to complete. And let's take a look at the scissor jack again. Although the appearance of the scissor jack is relatively simple, we can still see its core components. Obviously, it is also a screw.

The lifting process of a shear jack also requires transmission around the screw, and the only difference is that the screw of the screw jack is vertically upward, while the screw of the shear jack is horizontally oriented. By transmitting in the horizontal direction, the overall structure of the shear jack is changed to achieve the purpose of lifting, which is the operation mode of the shear jack. Therefore, from a certain perspective, The scissor jack is also a screw jack.