The Rotary paddle bin level indicator is based on the principle of rotating machinery. The motor-driven paddles rotate continuously at a standard rotation speed of one revolution per minute. The increasing bulk material in the silo or container buries the paddles. This blocks the rotation and generates a counter-torque. This reactive torque turns the built-in rotatable motor out of its original position and signals the switch via the switch arm to open the switch. The second switch delays cutting power to the motor. If the level drops again, the paddles are exposed, and the spring will spring the motor back to its original position. At this time, the motor is powered on and then sends out an output signal. The paddles begin to spin continuously again. Extended reading: Radar Level Sensor Working Principle