What is the Transfer Case and How Does it Work?

The transfer case is a gearbox that splits the power between the front and rear axles on 4-wheel drive vehicles. In all-wheel-drive vehicles, the transfer case helps to shift power from one axle to another, depending upon traction conditions. Lubricating fluid in the transfer case, called gear oil, helps keep the gears cool, clean, and turning smoothly. Gear oil additives break down in all gearboxes at different intervals. Replacing this fluid at owner’s manual recommended intervals can help prevent premature wear and damage caused by contaminated or broken-down gear oil.