Locking differential
A locking differential is a mechanical component, commonly used in off-road vehicles, that is designed to overcome the limitations of normal differentials by selectively locking the rotation of the wheels on an axle relative to one another, as if on a common shaft. In contrast to open differentials or limited-slip differentials found in many roadgoing cars, a locked differential forces both wheels to turn at the same speed, regardless of the traction (or lack thereof) available to each wheel individually.