Dell XPS 13 Ultrabook Review. Dell's XPS 13 Ultrabook starts at $999. So you have a MacBook Air, a man sitting next to me on a flight from New York to San Francisco says to me as he gestures at the laptop stuffed in my seat pocket.
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.
Differential Gear Ratio determines the number of times the drive shaft (or pinion) will rotate for each turn of the wheels (or ring gear). So if you have a 3.73:1 gear ratio the drive shaft turns 3.73 times for every turn of the wheel.