Abstract: An air cylinder operates a loose link cam fixed to a rod which pivots the hatch cover which is normally latched closed. As the cylinder is operated, the first portion of the movement unlatches the cover and the remainder of the movement swings the cover up to an over centre position whereupon it falls by gravity to the fully opened position without any further movement of the cylinder. The loose link cam permits the cover to move through approximately 180.degree. during the opening motion. when closing the cover, the same action takes place with the latch moving to the closed position by means of a spring and being displaced by the cover falling to the closed position by gravity once it has been moved by the loose link cam to the over centre position. The upper surface of the latch hook is curved so that the edge of the cover cross bar strikes the latch and displaces same as the cover closes and which is then returned to the latching position by the spring.