Classification of Steering Rack

Steering Rack is the most important part in the steering system of a car. Commonly used are rack and pinion type, worm crank pin type and recirculating ball type.

Rack and pinion Steering Rack

It is the most common Steering Rack. Its basic structure is a pair of intermeshing pinion and rack. When the steering shaft drives the pinion to rotate, the rack will move in a straight line. Sometimes, the steering wheel can be turned by directly driving the tie rod by the rack. So, this is the simplest Steering Rack. It has the advantages of simple structure, low cost, sensitive steering, small size, and can directly drive the tie rod. It is widely used in automobiles.

Worm Crank Pin Steering Rack

It is a Steering Rack with the worm as the driving part and the crank pin as the follower. The worm has a trapezoidal thread, and the finger-shaped tapered finger pin is supported on the crank with a bearing, and the crank is integrated with the steering rocker shaft. When turning, the worm is rotated by the steering wheel, and the tapered finger pin embedded in the spiral groove of the worm rotates on its own, while making a circular motion around the steering rocker shaft, thereby driving the crank and the steering drop arm to swing, and then through the steering transmission mechanism to make the steering wheel deflection. This kind of Steering Rack is usually used on trucks with large steering force.

Recirculating Ball Steering Rack

The main structure of the recirculating ball power steering system consists of two parts: the mechanical part and the hydraulic part. The mechanical part is composed of shell, side cover, upper cover, lower cover, circulating ball screw, rack nut, rotary valve spool, fan gear shaft. Among them, there are two pairs of transmission pairs: one pair is a screw rod and a nut, and the other pair is a rack, tooth fan or fan shaft. Between the screw rod and the rack nut, there are recirculating rolling steel balls, which change the sliding friction into rolling friction, thereby improving the transmission efficiency. The advantage of this Steering Rack is that it is easy to operate, has little wear and long life. The disadvantage is that the structure is complex, the cost is high, and the steering sensitivity is not as good as the rack and pinion type.