The system responsible for turning and changing direction of the car is called the car steering system. The commonly used steering systems on the market are mainly divided into two categories: mechanical steering and power steering.
The mechanical steering system is connected by the steering wheel and the steering column. The steering column head is connected to the tie rod between the two wheels. When the steering wheel turns, it will drive the steering column to turn. The steering column will pull the tie rod to the left or right, and the wheels can turn left or right. This is the most basic principle of steering wheel steering. Because this design is too rough, when the steering wheel is not dead, the wheels have already turned to the maximum angle, that is, the steering angle of the steering wheel and the wheel is the same. The industry says that the steering transmission is 1:1, that is, the steering wheel turns the same angle as the steering wheel. This design does not meet the steering parameter regulations of motor vehicles. This design is very dangerous for motor vehicles, because the transmission ratio is 1:1. When the steering wheel turns one degree, the wheel will turn one degree. If the steering wheel turns 5 degrees, the wheel will also turn 5 degrees. If the driver makes a wrong turn on a rugged road due to the shaking of the vehicle, the wheel will respond immediately, which may cause a major traffic accident, which will be very dangerous.
In order to solve this problem, a rack-and-pinion steering design was developed. A bevel gear, also called a helical gear or steering gear, was added to the end of the steering column. This gear meshes with a rack, which is connected to the front wheel through a steering rod. When the steering wheel is turned, the steering gear drives the rack to move left and right, which drives the rod to push and pull the front wheel to achieve a turn. Due to the addition of racks and pinions in this design, the steering transmission ratio becomes smaller. According to the requirements of the national standard, this ratio is between 12:1 and 24:1. Therefore, for a family car, when the wheel is returned to the correct position, the steering wheel needs to be turned one and a half turns before it can be stopped. In other words, the steering wheel needs to be turned three times from the extreme left to the extreme right. Now you should know why the steering wheel is designed to be round.
The current optimized design is still relatively rough, because its steering power transmission is relatively direct, and the steering feedback felt by the hand is also very direct. In layman’s terms, when encountering potholes, the vibration of the wheel will be directly transmitted to the hand through this series of connection components, which is often called the hand-beating phenomenon, and sometimes even the steering wheel cannot be held. Therefore, in order to optimize the design, it was modified again, and the original gear rack type direct meshing connection was changed to a method of using multiple steel balls to transfer power, and the steel balls were used to circulate along the grooves to transmit steering power. In this design, the circular movement of the steel balls in the grooves can effectively absorb the impact from the road surface and play a good shock-absorbing role, so that the driver can get a smoother steering feel. However, this design cost is relatively high, and is usually only used in buses, trucks and off-road vehicles.
Summary:
The steering system optimized by the above two rounds cannot actually meet the safety and comfort requirements of modern cars. The design of the mechanical steering system is relatively simple. It uses the driver’s physical strength as the steering energy, which will require the driver to consume a lot of physical strength. Because the steering force used is different due to different vehicle loads, when using this type of steering system, the steering wheel will be heavy and very difficult to turn.