Transfer Case or transfer box it’s a gear system that divides the power between the front and rear axles of the four-wheels-drive, all-wheel-drive, and other multiple powered axle vehicles.
It is mounted at the end of the transmission and splits engine power that it’s sent to the front and rear drive shafts. For some of the four-wheel vehicles the transfer case is at the command of the driver. Which means that the driver can use the option of engaging the transfer case in two-wheel drive mode or four-wheels drive mode. Other cars are having a permanent all-wheel drive mode and can’t be switched.
THERE ARE 3 TYPES OF TRANSFER CASES:
Part-time 4 WD
Full-time 4 WD
Active 4 WD
There are a variety of transfer boxes with a variety of names and levels of performance, and are using electronic, computerized or mechanical systems to adjust the amount of power sent to axles according to the wheel slip.
Part time 4WD is the most common transfer case and allows you to operate the vehicle in four-wheel-drive high range 4(Hi) and low range (4Lo) or two-wheel-drive
SPECIFICATIONS OF THE PART-TIME 4WD TRANSFER CASE (TRANSFER BOX)
- Offers smoother operation on pavement
- Fuel Economy because the front driveshaft and axle can be cut-off from power.
- Are generally the strongest transfer cases being designed for real off-road use
- Gives the driver the option of choosing the type of operation (on or off) according to the road condition.
Specifications of the Permanent or full-time 4WD:
It’s the simplest type of transfer case it send power to the front and rear axle all the time.
Some are coming with 4Hi lock position that locks differential to improve traction on slippery pavements.
Specifications of the Active 4WD:
It’s the easiest type of transfer box being active at all the times
It acts as the part-time transfer case and permanent transfer case according the road surface.
It’s operating all the 4 wheels at a time
TRANSFER CASE MAINTENANCE:
The transfer case is serviced by periodically changing and replacing the fluids as per your owner’s manual recommendations. Usually every 30.000 miles the fluids should be drained and replaced with fresh ones, mostly for the cars use often the four-wheel function. . Transfer cases can get filled with gear oil, automatic transmission fluid or other fluids.
SYMPTOMS OF A DAMAGED TRANSFER CASE or TRANSFER BOX:
Usually it gets difficult to shift gears or drive the car. The symptoms of a failure in the transfer box can vary, depending on type of the transfer box your car has and the problem but the most encountered ones are:
- Grinding noise coming from underneath the vehicle
- Vehicle jumps in and out of four-wheel drive
- Difficulty shifting gears
- Fluid leak
- Transmission warning light.
- Car doesn’t accelerate fast or move at all.
Specialist advice: It is important to check the level and the quality of the transfer box fluid every time you change the car oil and filters, also should be checked if the transfer box has leaks or any damages as the fluid might leak from the output shaft seals, input shaft seal, case gaskets and drain plug gaskets and lead to a bigger damaged.
Also if you are thinking of purchasing an aftermarket vehicle with a transfer case it’s better to have a certified expert inspect the case exterior, the fluid condition and test drive the car to make sure that everything is fine.