Its internal structure adopts a new type of special-shaped wedge with optimized design. In addition to impact resistance and large backstop torque, it also cleverly uses the centrifugal force of its own rotation: when the forward rotation speed of the input shaft is higher than the minimum speed, the internal work of the backstop can be adjusted. Realize no contact, zero wear and long service life. Widely used in belt conveyors, bucket elevators, scraper conveyors and other equipment with backstop requirements.