When the screw jack is working, the handle is pressed by external force to drive the rotation of the ratchet group, which can drive the connected small umbrella gear to rotate. The small umbrella gear meshes with the large umbrella gear, which can drive the rotation of the thrust bearing connected to it. Finally, it drives the rotation of the screw of the screw jack. In this way, the lifting sleeve screwed on the screw can smoothly achieve lifting and lowering, and our jack can perform upward and downward movements. We want to control the lifting of the screw jack by changing the direction of the jack teeth.