A linkage mechanism is disclosed that produces high travel advantage in one phase of linear actuator motion and high mechanical advantage in another phase of linear actuator motion. The linkage mechanism may be powered by a hydraulic actuator system and is capable of producing high preloads and a high amount of travel with minimal actuator motion or force. The linkage mechanism may be used to secure a hatch door to a pressure vessel housing or may be used in any environment involving high pressure differentials, for example.

A linkage mechanism is disclosed that produces high travel advantage in one phase of linear actuator motion and high mechanical advantage in another phase of linear actuator motion. The linkage mechanism may be powered by a hydraulic actuator system and is capable of producing high preloads and a high amount of travel with minimal actuator motion or force. The linkage mechanism may be used to secure a hatch door to a pressure vessel housing or may be used in any environment involving high pressure differentials, for example.

A vacuum system for use in excavation operations. The system uses a tank having an open end that is closed by a door. The door is opened and closed by a door lifting assembly made up of an upper linkage arm, a lower linkage arm and a hydraulic cylinder. A socket is formed in the upper linkage arm, and a shaft housing is formed in the lower linkage arm. The shaft housing engages with the socket to latch the door closed. The upper linkage arm is attached to the door at a first pivot axis and is attached to the lower linkage arm at a second pivot axis. The lower linkage arm is attached to a side of the tank at a third pivot axis. When the door is open, the second pivot axis extends below a reference plane that contains the first and third pivot axis.

A vacuum system for use in excavation operations. The system uses a tank having an open end that is closed by a door. The door is opened and closed by a door lifting assembly made up of an upper linkage arm, a lower linkage arm and a hydraulic cylinder. A socket is formed in the upper linkage arm, and a shaft housing is formed in the lower linkage arm. The shaft housing engages with the socket to latch the door closed. The upper linkage arm is attached to the door at a first pivot axis and is attached to the lower linkage arm at a second pivot axis. The lower linkage arm is attached to a side of the tank at a third pivot axis. When the door is open, the second pivot axis extends below a reference plane that contains the first and third pivot axis.

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.

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.

A hinge assembly to pivotably mount a blind flange to a weld neck flange includes a front assembly having a front plate and a plurality of front link plates coupled to the front plate, the front plate having a plurality of openings, each opening in the front plate coupled to mechanical fasteners to secure the front plate to the blind flange, a rear assembly pivotably mounted to the front assembly and having a rear plate and a plurality of rear link plates coupled to the rear plate, the rear plate having a plurality of openings, each opening in the rear plate coupled to mechanical fasteners to secure the rear plate to the weld neck flange, each front link plate disposed between a pair of adjacent rear link plates, and a pin disposed through each front link plate and the pair of adjacent rear link plates.

A door assembly for a pressure vessel includes a door, a hub to attach to the pressure vessel and to receive the door, and an annular seal to seal between the door and the hub. A hinge arm is coupled to the hub and to the door and is able to pivot relative to the hub about a hinge axis. A door actuator having an elongate member extending along an actuator axis is spaced-apart from the hinge axis and coupled to the hub and to the hinge arm. The elongate member travels with the hinge arm when the arm pivots relative to the hub, and rotates about the actuator axis. The door actuator is configured to cause the seal to engage sealingly the hub and the door.

Apparatus to protect sealing surfaces of thief hatches are disclosed. An example apparatus includes a base attachable to a tank around an aperture in the tank. The example apparatus further includes a spacer supported by a support surface of the base. The example apparatus also includes a cover selectively moveable between a closed position covering the aperture and an open position providing access to the aperture, the spacer separating the cover from the base.

A door assembly for a pressure vessel includes a door, a hub for receiving the door, and an annular seal to seal therebetween. A hinge arm is coupled to the hub and to the door and is pivotable relative to the hub about a hinge axis. A door actuator having an elongate member extending along an actuator axis is spaced-apart from the hinge axis and coupled to the hub and to the hinge arm. The elongate member travels with the hinge arm when the arm pivots relative to the hub, and rotates about the actuator axis.