Wheel-shaped devices for controlling the direction of travel of automobiles, ships, airplanes, etc. Its function is to convert the force exerted by the driver on the edge of the steering wheel into torque and transmit it to the steering shaft. The first cars were driven with rudders. It transmits the violent vibration generated in the driving of the car to the driver, making it more difficult for him to control the direction. When the engine was changed to be installed in the front of the car, due to the increase in weight, the driver could no longer use the rudder to drive the car. The new design of the steering wheel came into being. It introduced a gear system between the driver and the wheel that was flexible in operation and well isolated from the violent vibrations from the road. Not only that, a good steering wheel system can also bring the driver a feeling of intimacy with the road. The steering wheel is generally connected to the steering shaft through splines, and its function is to convert the force exerted by the driver on the edge of the steering wheel into torque and then transmit it to the steering shaft. When steering with a larger diameter steering wheel, the driver's hand force on the steering wheel can be less. The steering drive shaft is used as a connecting piece between the steering gear and the steering shaft, which is beneficial to the generalization of the steering gear, compensates for the errors generated during manufacture and installation, and makes the installation of the steering gear and steering wheel on the vehicle more reasonable.