An apparatus for sealing a vacuum tank door. The apparatus comprises a circular flange attached to a door panel of a vacuum tank, a horizontal crossbar connected to the center of the door panel and a lifting assembly. The lifting assembly comprises an upper linkage arm, a lower linkage arm, and a hydraulic cylinder. Activation of the hydraulic cylinder causes the linkage assembly to move downwards pulling on the horizontal crossbar and pulling the vacuum tank door towards the tank. Activation of the hydraulic cylinder also causes a connection point of the lower linkage arm and the upper linkage arm to move over-center of the connection between the lower linkage arm to the to the tank creating a tight seal between the vacuum tank door and the tank.