The circular ball steering gear consists of a driving pair composed of steel balls in a spiral groove formed by screws and nuts, and a driving pair composed of a tooth rack on the nut and a tooth fan on the rocker shaft, as shown in FIG. 1-4.The advantages of recirculating ball steering gear are: the transmission efficiency can reach 75%~85%; Steering gear transmission ratio can be changed; Stable and reliable work; The clearance between rack and gear sector is easy to adjust; Suitable for integral power steering..The main disadvantages of recirculating ball steering gear are: high reverse efficiency, complex structure, manufacturing difficulties, manufacturing precision requirements high..Recirculating ball steering gear is mainly used in trucks and buses..