Abstract: A pressure vessel such as a steam cooker has a novel variably sloped cam arrangement for sealing a warped access door against the inside of an access opening. Such access openings are typically of circular configuration, and the access doors are warped about one axis for insertion therethrough. The latching mechanism of this invention enables the door to be swung from an open position into a first position inside the pressure vessel and then to be moved rapidly into a second position in engagement with an inside rim of the access opening. This rapid movement is accomplished by rotation of an operating handle through a relatively small angle. Thereafter continued rotation of the handle stresses the access door, removing the warp therefrom and sealing the door against the inside rim of the access opening. The latter door stressing rotation produces relatively little motion of the door for a relatively large angular rotation of the operating handle.