A four-wheel drive vehicle can offer many benefits. In order for you to shift your truck from two-wheel to four-wheel drive, you need to engage the help of either the chain drive or gears inside the transfer case.
The transfer case utilizes the driveshafts for the front and rear axles to adjust the gear ratio and rotational speed of all four tires. The purpose is for the wheels to move at the same speed. This is achieved by slowing the speed at which the tires turn.