A ball detent is a simple mechanical arrangement used to hold a moving part in a temporarily fixed position relative to another part. Usually the moving parts slide with respect to each other, or one part rotates within the other. Ball detents are commonly found in the selector mechanism of a gearbox, holding the selector rods in the correct position to engage the desired gear. Other applications include clutches that slip at a preset torque, and calibrated ball detent mechanisms are typically found in a torque wrench.