What is a transfer case?

A transfer case is found on four wheel drive vehicles, it is the mechanical device that splits the engine power, directing it to the front and rear axles. A typical four wheel drive train arrangement consists of the engine, the transmission and then the transfer case. In a conventional two wheel drive vehicle the drive shaft is connected to the output of the transmission, the driveshaft’s for a four wheel drive vehicle are both connected to the transfer case. Depending on the vehicle the transfer case may contain a chain drive or a gear set. As well as distributing power to front and rear the transfer case has the ability to shift the vehicle from two wheel drive to four wheel drive and into neutral.

When the vehicle is operating in two wheel drive mode it is the transfer case that that ensures that all engine power is directed to the rear wheels via the drive shaft. If the vehicle is being towed, and many off road vehicles are, when the transfer case is in neutral the transmission is disconnected which eliminates the potential of damage.

When the vehicle is being operated off road or in slippery or snowy conditions the transfer case allows all four wheels to turn; the front and rear wheels turn at the same rate. Four wheel drive basically doubles the traction over rear wheel drive only; this feature allows the vehicle to traverse difficult conditions while still maintaining some speed. Although the vehicle can operate at normal speeds while four wheel drive is engaged, most vehicle manufacturers suggest that the speed is reduced. The four wheel drive option is very popular in areas of the country where there is a great deal of snow and ice.

When the vehicle is in four wheel drive it will be geared low or high. Low is the best position to use if the vehicle becomes mired down or is operating in conditions where the traction is poor. When the transfer case is in low, the engine can operate at a higher rate of rpm’s while the lower gear ratio increases the power that is on the road. The wheels turn quite slow, there is better traction and less chance of losing traction.

Under normal daily driving conditions the vehicle would rarely be put into four wheel drive. Vehicle manufacturers suggest that four wheels be engaged through the transfer case every six months or so and driven 25 or 30 miles just to ensure the components are well lubricated.

If you own a four wheel drive vehicle and experience problems with the transfer case you are invited to take the vehicle to Trans Works Transmission LLC. All technicians are ASE certified and have a large stock of repair and replacement parts on hand.You can also follow them on Twitter.

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