What Is a Transfer Case?

A transfer case is a component in four-wheel and all-wheel-drive vehicles that uses gears or a chain-drive to transfer power from the transmission to the front and rear axles of the vehicle. Some transfer cases are engaged only part of the time, while others are engaged all the time.

Transfer Cases at Work

Part-time transfer cases transfer power to all four wheels only when necessary, such as in inclement weather or while off-roading. "Full-time" transfer cases send power to all four wheels at all times. In this case, the car or truck has all-wheel drive. On some all-wheel-drive vehicles, the power is shifted among the four wheels to whichever wheel has the most traction.

Driver Selection

On many vehicles, particularly on pickup trucks and SUVs, the four-wheel-drive system is part time, with four-wheel drive being engaged only when the vehicle is encountering poor weather (usually snowy conditions) or is being used off-road. On most current vehicles, transfer case settings can be changed without the driver stopping the vehicle. But on older models, users often had to come to a complete stop and shift the transmission into neutral. In some cases, motorists even needed to get out of the truck or SUV and lock the front hubs.

All-Wheel Drive

All-wheel drive is more prevalent on cars than trucks and SUVs, although it is becoming more common on car-based SUVs. In most cases, the driver has no control; the system is fully automated and a computer uses sensors to determine how power should be distributed.

Uses on the Silverado

On the four-wheel-drive versions of the Chevy Silverado pickup truck, the transfer case is used to control the four-wheel-drive system. When the driver needs to place the truck into four-wheel drive, he or she will use the transfer case to engage the system and send power to all four wheels for maximum traction in certain conditions.

Warning

Using a part-time system on dry pavement can lead to damage to the vehicle and premature tire wear, so check your owner's manual.

Source:

Wikipedia