Four Wheel Drive

Four wheel drive mode is generally used for low traction conditions like snow, mud, loose gravel etc, and is generally available in the following two variants:

• 4 High
• 4 Low

Essentially, in such a drive system, all the 4 wheels receive torque from the engine simultaneously. These off-road vehicles offer better control on many surfaces and are an important part in rally racing, through difficult terrain.

4 High is used for ‘regular’ easy to moderate off-roading, and vehicle can be driven at higher speeds. Generally, the move to this mode is possible while driving, but it recommended having a low constant speed and less strain on the engine during the switchover.

4 Low is used for extreme off-roading, for moving at extremely slow speeds (<25mph generally) in real difficult terrain like steep hills. Typically the switchover to this mode is done when the vehicle is stationary.

Four wheel drive is not recommended on good roads, as it does not allow the front and rear axels to turn at different speeds, especially required at corners.

There is another class of vehicles called All-Wheel Drive that are designed to function on all types of surfaces, both on and off road, and typically cannot be switched off. They use differential to allow front and rear axels to turn at different speeds.

Different manufacturers implement these systems differently, so I would suggest one to research the specific targeted vehicle to understand more about it’s off-roading capabilities, and it’s recommended usage.