A transfer case is an intermediate gearbox that transfers power from the transmission of a motor vehicle to the driven axles of four-wheel-drive, all-wheel-drive, and other multi-axled on- and off-road machines. A part of the vehicle's drivetrain, it employs drive shafts to mechanically deliver motive power. The transfer case also synchronizes the difference between the rotation of the front and rear wheels, and may contain one or more sets of low range gears for off-road use.
Inside of a 231 New Process Gear transfer case. Part-time/Manual, shift on the fly
The levers on a Kubota tractor for selecting between 2WD and 4WD (left) and high and low gear ranges (right) are connected to the transfer case . The transfer case is currently in high-range, rear-wheel-drive.
Transmission (mechanical device)
A transmission is a mechanical device which uses a gear set—two or more gears working together—to change the speed or direction of rotation in a machine. Many transmissions have multiple gear ratios, but there are also transmissions that use a single fixed-gear ratio.
Hydraulic automatic transmission (cutaway view)
Transmission for a Bristol Sycamore helicopter
Mazda M5OD manual transmission (viewed from the engine side)
Transmission internals for a 2009 Volkswagen Golf