Abstract: A security device for a cart wheel utilizing a housing which is mounted to the cart in the vicinity of the wheel. A locking element supported to the housing and is selectively movable into positions engaging the cart wheel or being disengaged from the cart wheel. A motor is employed to move the element in such reciprocal motion and is operated by a controller. The controller includes a counter to determine the number of revolutions completed by the wheel, and a trigger for starting the motor upon receipt of a signal from the counter representing a preselected number of revolutions completed by the wheel.