The crown gear differential

Today I'm posting a great invention used in Audi RS 5 , Known as Crown gear Differentail.

Exactly 30 years after the debut of the first quattro, Audi 

presents a new, innovative evolutionary stage of its permanent 

all-wheel drive system for longitudinal engines – the quattro 

drive with crown gear differential and torque vectoring. The 

technology will debut in the new Audi RS 5 high-performance 

coupé, with which Audi is further extending its competitive 

advantage.

2010 marked 30 years since the introduction of the quattro system and saw the introduction of a ‘torque vectoring’ capability to its system with the help of a ‘Crown gear differential’

Using the crown gear geometry, under normal conditions 60% of engine torque is sent to the rear axle and the remaining 40% to the front axle. Introduced first in the RS5, the self-locking effect of the differential can divert most of the torque to the axle with better traction. 85% of torque can now be diverted to the rear axle if the front axle has less grip and a maximum of 70% torque to the front axle in case of low grip on the rear axle.

The crown gear differential is different from its predecessors in being able to distribute a wider bandwidth of torque with better traction and with instant response times. Moreover, it is very low in weight and compact in size.

Torque vectoring is achieved with the help of the crown gear differential using a computer controlled brake management system. The brakes are applied to measured degrees based on the computer’s analysis of the expected slippage during cornering to redistribute power to individual wheels. The torque distributed to the outside wheels during such braking action of the inner wheels while cornering enables them to send more torque to the road and this happens continuously and acts to reduce to very high degrees any signs of under steer.

The functioning of the crown gear differential and the torque vectoring program reduces the need for the electronic stability program to intervene until absolutely necessary thereby maintaining a mechanical control of the vehicle’s drive characteristics with minimal electronic interference.