A particular component used on all-wheel and four-wheel drive to split up the power of the engine is known as a transfer case. The transfer cases can be the central unit of all four wheels and some all-wheel vehicles.
The primary function of transfer cases is to transmit power to all the vehicle’s four wheels and keep them running. However, in vehicles that run on two wheels, the engine generates the energy transmitted to the drive-axle differential followed by the drive wheels. In a four-wheel vehicle, the power is driven both forward and rear axle differentials.
Transfer cases and their types
There are three basic types of transfer cases as discussed below:
- Part-time 4WD
Being the most common type of transfer case, the part-time 4WD allows vehicle operation with a two-wheel drive, four-wheel drive high-range and four-wheel drive low-range. Due to the presence of part-time 4WD, the vehicle offers smooth performance on the pavement. Besides, the part-time 4WD cuts off the axle and the front driveshaft, reducing fuel consumption ultimately. Generally, part-time transfer cases are the strongest because they are manufactured for rough and patchy areas and are provided in trucks and other utility vehicles.
- Full-time 4WD
The full-time 4WD is the simplest transfer case that transmits power to the rear axle and the front. Sometimes, a full-time 4WD uses a high differential to avoid driveline that gets bound on hard surfaces. In addition, to provide better traction of slippery and soggy surfaces, sometimes a full-time 4WD lock position is offered. This feature also secures the vehicle while operating on dry pavement.
- Active 4WD
One of the easiest transfer cases to use is the active 4WD, as it barely requires any input from the driver. In an active 4WD, a combination of full-time and part-time transfer cases is merged with automated, mechanical or electronic means to measure the power transmitted to the axles. The amount of energy to be transmitted is dependent on the wheel slip. In the active 4WD, the owner does not have to take any initiative to switch on to anything. These transfer cases are designed to impart smooth operation without the driver having to intervene. They are present in all vehicles, starting from trucks to luxury sports cars.
Many might question the difference between the transfer case in an AWD and a 4WD vehicle. The former is devoid of the application of additional torque, multiplying a low gear ratio, unlike the latter. Even if a vehicle is not on a four-wheel drive, the transfer cases are always in active mode.
When buying transfer cases, ensure that ASE certified technicians thoroughly examine the case’s exterior. Also, the fluid level and the condition of the transfer cases should be checked to prevent any damage. Regarding the fluid type of the transfer case, follow the instructions and the vehicle manufacturer’s recommendations and do not forget to ask him how often it has to be changed.