Parts Used For Four Wheel Drive

Having a vehicle with four-wheel drive can come in handy in many situations, especially when it comes to inclement weather. A car or truck with four-wheel drive and four good tires is invaluable during snow and ice storms. Roads that would be impassible or dangerous can be traversed much more easily with the traction of all-four wheels helping to power the vehicle. However, some people confuse four wheel drive and all-wheel drive. Usually when a vehicle is referred to as four-wheel drive, it means that it has a part-time system where four-wheel drive can be engaged in low-traction conditions. All-wheel drive usually means that the car constantly has four powered wheels. There is no option to switch to front-wheel drive.

Because of this added power, four-wheel and all-wheel drive vehicles have very different components than two-wheel drive vehicles. The main components include front and rear differentials and a transfer case.

A four-wheel drive vehicle has two differentials. One of them is located between the two rear wheels and the other is located between the front wheels. The purpose of the differentials is to send torque from the transmission or driveshaft to the wheels of the vehicle. In vehicles with independent suspension the power is transferred through a cv joint. However, the wheels of a vehicle rotate at different speeds when turning corners, because the radius of the turn makes it necessary for wheels on the outer edge of the turn to travel further than inner wheels. The differentials make it possible for the drive wheels to rotate at different speeds while still supplying equal amounts of torque to each wheel. Without differentials the inner wheels would be forced to rotate at the same speed, which could result in either spinning of the inner wheels or dragging of the outer wheels.

A transfer case is another important component of four-wheel drive vehicles. The purpose of the transfer case is to "transfer" or split power between the front and rear axles of the vehicle. While the differentials handle power difference between inner and outer wheels in a turn radius, the transfer case allows for speed differences between the front and rear wheels. In a part time four-wheel drive vehicle, a transfer case locks the front-axle driveshaft to the rear-axle driveshaft. This makes it so the wheels must spin at the same speed. Because of this, part-time four-wheel drive should only be used in low traction situations. These important components make it possible for a vehicle to have all four-wheels powered, providing important traction in off-road and poor weather conditions.