Screw steering gear. The helical gear unit consists of a flat-threaded screw, mounted on the end of the steering shaft and the nut. The rotation of the bearing bolt in the circumference causes the movement of the nut and fork, which actuate the longitudinal rod via the steering arm. Screw gears are rarely used, recently they have been used, e.g.. in newly manufactured trucks of Soviet production MAZ-300 and MAZ-503. The rack gear is the simplest one in operation, and execution. A rack and a driving gear wheel are mounted in the body, connected by a rubber joint to the steering shaft. The rack moves when you turn the steering wheel, which turns the steered wheels through a system of articulated rods. Rack gears are mainly used in light cars, with independent suspension of the front wheels. Such gears are generally characterized by a small gear ratio.