Ratchet wheel type chain tightener of scraper conveyor

The ratchet wheel type chain tightener comprises a ratchet wheel and a pawl matched with the ratchet wheel, the ratchet wheel is coaxially fixed with a working output shaft of a speed reducer, the pawl is arranged on a pawl rotating shaft on a bottom plate of the chain tightener, the pawl rotates forwards to be clamped into the ratchet wheel to be in a return locking state, and the pawl rotates reversely to be separated from the ratchet wheel to be in a non-locking state. A pawl non-locking mechanism on the bottom plate comprises a pin tongue capable of elastically sliding, a protruding return clamping jaw is arranged on the pawl, and when the pawl is separated from the ratchet wheel, the pin tongue blocks the return clamping jaw to prevent the pawl from being clamped into the ratchet wheel; one end of a return tension spring in the pawl return mechanism is connected with a fixed pin on the bottom plate, and the other end of the return tension spring is connected with the outer end of a pull handle on the paw