Do you know the type and structure of automotive steering gears? As someone who has been in the steering gear business for 5 years and now works as a general manager in SAP, I have compiled three days of information and combined it with our practical operations to answer you in an easy-to-understand way!

1 Automotive steering gear types and structure working principle

  1. Rack and pinion steering: It is the most common type of steering gear. Its basic structure is a pair of mutually meshing pinion and rack. When the steering shaft drives the pinion to rotate, the rack will do linear motion. Sometimes, the rack can drive the cross-road directly to make the steering wheel steer. Therefore, this is the simplest type of steering rack. It has the advantages of simple structure, low cost, sensitive steering, small size, and can directly drive the cross tie bar. It is widely used in automobiles.
  2. Worm crankpin type steering rack: It is a steering gear with a worm as the active part and a crankpin as the follower. The worm has a trapezoidal thread, and the finger-like tapered finger pin is supported on the crank with a bearing, and the crank is integrated with the steering rocker shaft. When steering, the worm is rotated by the steering wheel, and the conical finger pin embedded in the spiral groove of the worm rotates itself while making circular motion around the steering rocker shaft, thus driving the crank and the steering arm to swing, and then deflecting the steering wheel through the steering transmission mechanism. This kind of steering gear is usually used in vehicles with a large steering force.

SP9801 RHD Steering Rack

  1. Circulating ball steering: The main structure of the circulating ball power steering system consists of two major parts: the mechanical part and the hydraulic part. The mechanical part consists of shell, side cover, upper cover, lower cover, recirculating ball screw, rack nut, rotary valve spool, and fan tooth shaft. There are two pairs of transmission pairs: one pair is the screw and nut, and the other pair is the rack, tooth fan, or fan tooth shaft. Between the screw and the rack, the nut is equipped with a steel ball that can be cyclically rolled, so that the sliding friction becomes rolling friction, thus improving the transmission efficiency. The advantage of this kind of steering is that it is light to operate, has low wear, and long life. The disadvantage is that the structure is complicated, the cost is higher, and the steering sensitivity is not as good as the rack and pinion type.

The housing is mainly for the rack and input shaft and its fixed and protective role, but also to limit the travel of the rack.

2 Introduction of automotive commutator

The automotive commutator is actually what we call steering gear, mainly a set of gear mechanisms to complete the rotary motion to linear motion, and also a deceleration transmission device in the steering system. At present, the more commonly used ones are rack and pinion type, circulating ball crank finger pin type, worm crank finger pin type, circulating ball – rack and pinion fan type, worm roller type, etc.

3 Structure and working principle of steering gear

The function of the steering gear is to increase the torque transmitted from the steering wheel to the steering knuckle and to change the direction of force transmission.

There are many types of steering gears, which are classified into reversible, irreversible, and limit reversible according to the force transmission, rack and pinion, worm crank finger pin, recirculating ball, and worm roller according to the structure of the steering gears.

SP9801 RHD Steering gear

4 Structure of steering transmission mechanism

The function of the steering transmission mechanism is to effectively transmit the motion and power output from the steering gear to the steering knuckles on both sides of the steering axle so that the steering wheels on both sides can be deflected effectively and the deflection of the two steering wheels can be changed according to a certain relationship to ensure that the relative sliding between the wheels and the ground is as small as possible when the car is steered and to absorb the recoil transmitted from the wheels to the steering wheel.

The steering transmission mechanism is mainly composed of the steering rocker arm, steering straight tie rod, steering knuckle (including steering knuckle arm and trapezoidal arm), steering cross tie rod, etc.

The material of the housing of the recirculating ball steering is generally cast iron, and the material of the housing of the rack and pinion steering is generally cast aluminum alloy.

Both serve roughly the same purpose, which is to support the gears, gear fans, or rack and pinion that make up the steering gear.