Wikipedia
A transfer case is a part of the drivetrain of four-wheel-drive, all-wheel-drive, and other multiple powered axle vehicles. The transfer case transfers power from the transmission to the front and rear axles by means of drive shafts. It 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.
Usage examples of "transfer case".
Then the hand paused briefly, and as he turned pages in the paper -- the fluttering of the paper was a fine distraction to anyone who might be watching, since the human eye is always drawn to movement -- the right hand slid down and affixed the metal transfer case to the magnetic holder, then returned for the paper, all in one smooth motion, done so quickly as to be invisible.
A carpeted hall led to a room that smelled like a chemistry lab, where two inappropriately cheerful attendants were loosening the screws on the transfer case- another man stacked the plywood against a far wall.
He simplified things by keeping it only two wheel drive, and lost the extra weight of the transfer case and the drive shaft.
The jeep's transfer case growled in protest as we slithered and bulled our way the last hundred feet.
The transfer case was still locked in four-wheel drive and all four tires spun and scattered wet stones and the car took off.