The transfer case is a specialized component used on four-wheel-drive vehicles. It is essential in cars that use both front and rear axles for driving. And in the case of 4×4’s, each of the four wheels needs traction.
In the simplest terms, a transfer case will split the power from the engine and send it to all four wheels using the front and rear axles. It is the center of the drivetrain system in four-wheel drive and four-wheel drive vehicles. In addition, off-road cars may use a transfer case that contains one or lower gear sets to handle more demanding terrain.
All four-wheel-drive vehicles come with a transfer case. The box, located just behind the transmission, takes the torque generated by the engine and distributes it to the drive axles. This part also synchronizes the rotations of the wheels and can contain low-range gears so you can take the vehicle off-road. There are several options that four-wheel drive vehicles use.
There are two primary choices in drive types. Each has its benefits depending on the use of the vehicle. One type is the gear-driven transfer case. This system uses gear sets to drive the front and rear driveshafts. This design works well with solid and heavy units. They are usually found on larger trucks. However, they appear more frequently in passenger cars.
Chain-driven designs, such as the 231j transfer case, drive only one axle. On rare occasions, some vehicles use this design to drive both axles. The 231j transfer case is quieter than a gear-driven version. Compact trucks, Jeeps, SUVs, and full-size trucks use this type of drive. However, many off-road severe drivers switch from this type of design to a gear-driven model. They prefer the additional power provided by the industry and tolerate the other noise.
As with transmission types, there are a few different types of shifts. One is the electronic shift on the fly (ESOF). This type of shift comes with a dash-mounted selector that selects between all-wheel drive and two-wheel drive. To activate the high four-wheel-drive selector, you must drive at a lower gear. If you want to start the four-wheel-drive at low speed, you must stop the vehicle and neutralize the transmission.
The other type of drive is the manual shift on the fly (MSOF). The MSOF has a selector lever located on the floor transmission hump. Sometimes, this type of shift has two sealed automatic front axle hubs with lock, unlock, or free selectors. As with the ESOF, your vehicle must be moving at a low speed to activate the high setting. In addition, to shift into the low-speed transmission, the car must be in neutral with the vehicle stopped.
When it comes to housing, like everything else, there are a couple of different options. The first option is a married transfer case housing. This means that the part is bolted directly to the transmission. This housing sits between the transmission output shaft and the rear of the main drive shaft. In some cases, the accommodation is part of the transmission, and the two share the same housing.
The other type of housing is a divorced/independent model. Unlike the married version, this one is not mounted directly to the transmission. Instead, it is located away from the transmission and connected by a driveshaft. This type of housing is found only on vehicles with a long wheelbase, such as a military or commercial vehicle.
A transfer case can be a combination of any of these types. A chain-driven model may be MSOF and contained in married housing, for example. The design of the part will depend on the manufacturer.