Closures for pressure vessels.

摘要

A closure for a large sized opening (102) in a pressure vessel (103) has a lid (101) longitudinally movable between an open position and a covering position in which it is aligned with the opening (102) but spaced apart from it, and perpendicularly displaceable between the covering position and a sealing position in which it engages the sealing edge (104) of the opening (103). The lid (101) is moved by a hydraulic or pneumatic ram(116) between the open and covering positions and iscarri- ed by rollers (109) mounted on shafts (106,106a) affixed to the lid, which run on longitudinal support surfaces (119). The shafts (106, 106a) are rotatably mounted in bearings (107) fixed to the lid and are coupled together (112,112a, 113) for simultaneous rotation, while the rollers (109) are eccentric relative to the bearings (107). The ram (116) applies torque to the shafts (106, 106a) in one sense during closing movement of the lid (101) and in the opposite sense during opening movement of the lid (101). A follower member (120) fixedly secured to one (106) of the shafts engages guide surface (119) to prevent the shafts (106, 106a) rotating during movement of the lid between the open and covering positions. The guide surface has an aperture (123) in it through which the follower member (120) passes when the lid reaches the covering position so that the shafts (106, 106a) rotate and the lid (101) is displaced from the covering position to the sealing position by the relative eccentricity of the rollers (109) and bearings (107). A cam surface is provided for guiding the follower member (120) during return displacement of the lid between the sealing position and the covering position.