The RLI rotary paddle switch is designed to detect high and low levels of bulk granular solids in bins, tanks, silos, and as blockage detectors in spouts. The detection of material is achieved by a rotating paddle. If material impedes the rotation of the paddle, the motor topples of its axis and triggers a contact. The power supply to the motor is cut and the contact signals that a critical level has been reached, which will cause the motor for any inlet or outlet to close down or start up. When the level of the material reaches normal levels again, the motor returns to its initial position and restarts.