SH-AWD is a active four-wheel drive system installed on Acura and Honda cars since 2004. It works in conjunction with traction control, stability control and other systems. It improves off-road capability, as well as vehicle dynamics and handling.
How it works
The main benefit of the SH-AWD system is the constant adjustment of the engine torque to the road conditions. Most of the torque is transferred to the axle that has the best grip in order to use the engine power most efficiently.
An electronically controlled multi-plate clutch acts as a center differential. The degree of locking affects the torque delivered to each axle. The front differential is open.
The rear drive unit consists of two planet gears with individual electromagnetic clutches. This allows 100% of the torque to be transferred to the rear axle and distributed to the wheel that has the better grip. On some models, the rear drive unit is equipped with an accelerator to increase the speed of the wheels.
However, some premium vehicles are equipped with a SH-AWD hybrid transmission, in which case the engine torque is only sent to the front axle is transferred. Two independent electric motors drive the rear wheels.
Technical properties of SH-AWD-System
| Type | Center differential | Rear axle differential | Start of production | Models equipped with this type of drive |
| Permanent all-wheel drive | Multi-plate clutch: The torque can be distributed to the axles in a ratio of 90:10 or 70:30, depending on the grip of the wheels. | 2 hypoid gears with electromagnetic clutches | 2004 | Honda Legend KB1, KB2; Acura RDX; MDX YD2, YD3; TL UC; ZDX; TLX |
| Permanent 4WD | With accelerator | 2009 | Acura RL KB1, KB2 | |
| Hybrid all-wheel drive | The SH-AWD control unit takes care of the torque distribution. | Not installed. Each wheel is powered by an individual electric motor, while the Dual Motor Unit (TMU) controls the torque delivered to the rear axle. | 2011 | Acura RLX; NSX |