We all have a clear concept about mechanical jacks, which is that their operating principle is mainly to do work through the interaction force between machines, and most of the work done by jacks is completed by the combination of gears and screws. Therefore, screw jacks are a typical representative of mechanical jacks. However, are all mechanical jacks equipped with screws? It's obvious that it's not like that.

Spiral jacks with screws can be collectively referred to as mechanical jacks, but mechanical jacks are not necessarily screw jacks. Today, we will learn about a special mechanical jack whose transmission device does not use screws, only gears. Its name is rack jack.

Firstly, we can talk about rack and pinion jacks. There are L-shaped and scissor shaped types of rack and pinion jacks, both of which are the most mechanical jacks with long rocking handles. This labor-saving principle is based on the lever principle.

The rack jack relies on the interaction between machines of the same style to complete the task. It mainly uses a lever to pry the rotation of gears, which mesh with the rack to drive the rack to move upward to complete the lifting. This is a special structure mechanical jack - the rack jack.