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In rear-wheel drive automobiles the central drive shaft (or prop shaft) engages the differential through a hypoid gear(ring and pinion). The ring gear is mounted on the carrier of the planetary chain that forms the differential. This hypoid gear is a bevel gear that changes the direction of the drive rotation.
This is made possible with the help of the rear differentialâs side gears and spiders. To put it simply, this mechanism is the one that decides the speed and the frequency of the turning of the axle and wheels in relation to the turning of the drive shaft. This is often referred to ring and pinion ratio. If for example you have a rear gear ratio of 3.73:1, this simply means that the drive shaft (which is connected directly to the pinion gear) is going to rotate 3.73 times to the wheels turning one, full rotation.