Types of all wheel drive system

All-wheel drive cars have a different drive system according to the road surface. There are mainly four types of the all-wheel drive system.

1. Part-time all-wheel drive
2. Full-time all-wheel drive
3. Automatic all-wheel drive
4. Selectable all-wheel drive

The part-time all-wheel-drive system cannot be used in the non-slippery condition you will have to drive such cars in rear-wheel drive condition.
AWD is not necessarily that it is a full-time all-wheel drive and 4 wheel drive is not just four off-road vehicles. They both are same but there is a minor difference between AWD and 4WD.

• Part-time all-wheel drive 

This is a temporary all-wheel-drive system. In normal condition, just one axle is driven while in slippery condition another axle is engaged by the driver by leaver or button.

This type of all-wheel drive does not have a centre differential.

When all-wheel drive is engaged the front and rear driveshafts are mechanically connected and rotated at the same speed.

• Full-time all-wheel drive 

This is a permanent all-wheel drive or permanently engaged all-wheel-drive system.

All-wheel is powered at all times and the vehicles with full-time all-wheel drive are equipped with a centre differential that lets each wheel travel different distances while turning.

This type of all-wheel drive used both on and off-road condition.he

In slippery condition, the centre differential can be locked, whether manually or automatically depending on the vehicle.

• Automatic all-wheel drive 

This is an on-demand all-wheel drive. Under the normal driving condition, only one axle is powered. when wheel slipping occurs at that condition the driving driveshaft rotates faster than the driven driveshaft and a multi-plate hydraulic clutch or other similar traction control device locks and engages another axle.

The difference between the traction devices that are used in full-time all wheel drive and automatic all wheel drive systems is that the device used in automatic all wheel drive system replaces the center differential.

• Selectable all wheel drive 

In selectable all wheel drive driver can choose between the 2WD mode or 4WD mode with automatic distribution of torque via viscous coupling vehicle behaves like the one with full time all wheel drive.

4WD with locked differential behaves like part-time all wheel drive.