Abstract: A hatch cover having a locking mechanism comprising a single hand wheel with a shaft threaded to the cover for limited up and down movement as the hand wheel is turned. A locking strap is hinged on one side of the hatch cover, releasably locked on the other side and has an opening through which the shaft extends. The locking strap is confined between the hand wheel and a thrust washer attached to the shaft in such a fashion that rotation of the hand wheel in one direction produces contact between the locking strap and thrust washer to force the cover downwardly. Rotation in the other direction lifts the hatch cover to permit unlatching of the locking strap and access to the hopper.