Worm steering gear. The following gears are among the most common steering gears: ordinary worm, cochlear globoid, screw and rack. Ordinary worm gear consists of a worm and a worm wheel. The worm is mounted on the lower end of the steering shaft, and a meshed worm wheel on the steering arm shaft. Rotating the worm causes a partial rotation of the worm wheel, and with it the steering arm. Worm gear, in which the snail works with the so-called. finger. By turning the steering shaft, an offset is achieved between the turns of the worm finger, and thus the corresponding movement of the steering arm. The gear ratio in these transmissions is 14-28, depending on the type of vehicle. Such large gear ratios are conditioned by the necessity to ensure ease and certainty of driving the vehicle. The globoid worm gear is a variation of the rarely used ordinary worm gear. The globoid worm, embedded in the bearings, has a variable diameter (the diameter of the screw is smaller in the middle). The double finger or roller in the globoid gear has a simplified structure, it is a section with two or three teeth, which in every position of the globoid cochlea are meshed in it. Double roller globoid gear is more convenient to use, because there is much less friction between the roller and the screw surface than e.g.. in the double-finger gear, or in an ordinary worm gear. The globoid gear is used in Star cars, FSO Warsaw, said 110, Polish Fiat 125P and others. The steering gear ratio in the Polski Fiat 125P is 16,4.