Subject: Automobile Engineering

Topic: Brakes, Steering & Front Axles

Difficulty: Medium

Rack & pinion steering gear is used on light vehicles like cars & in power steering. It is simple, light & responsible. It occupies very small space & uses lesser no of linkage components compared to the worm & wheel type of gear.

Fig: 15.1 shows a rack & pinion steering gear, There is no damping out of road feel as the tyres meet. There is no damping out of road after shock & vibrations type of steering system. As gear ratio is limited to steering wheel & pinion gear so it can be used in small operated by light force whereas in large vehicle this can be disadvantage hence re-circulating ball type are found in truck. In this type of steering gear, a binson mounted at the end of the steering shaft. The pinion engages with the rack which is provided with ball joint at its each end in order to allow for the rise & fall of wheel. The rotary motion of the steering wheel is transmitted to the pinion. The circular motion of pinions is convert into the linear rack movement, which is further transmitted to tie rods to the stub axle through ball joint. The ball joint arrangement allow the spindle ends of tie rods to moves up & down with the spindle & wheels. This type of steering gear provides sufficiently low gear reduction for car & it is quite suitable even for heavier motor vehicles if assisted with power.