Large high vacuum valve

Claim 1

A GATE VALVE ADAPTED FOR SEALING LARGE HIGH VACUUM LINES, COMPRISING A CASING HAVING A PAIR OF OPENINGS COMMUNICATING WITH A PASSAGE THERETHROUGH THAT IS ADAPTED TO BE SEALED, SAID CASING ALSO HAVING A CHAMBER COMMUNICATING WITH SAID PASSAGE, SAID CHAMBER EXTENDING IN A DIRECTION TRANSVERSE TO SAID PASSAGE, AND HAVING A WIDTH GREATER THAN THE DIAMETER OF SAID PASSAGE SO THAT A SHOULDER IS PROVIDED IN SAID CHAMBER ON ONE SIDE THEREOF AROUND ONE OPENING TO SAID PASSAGE AND A SEALING SURFACE IS PROVIDED IN SAID CHAMBER ON THE OPPOSITE SIDE THEREOF AROUND THE OTHER OPENING TO SAID PASSAGE, A MOVABLE PLATE POSITIONED IN SAID CHAMBER, SAID PLATE HAVING A WIDTH GREATER THAN THE DIAMETER OF THE OPENINGS TO SAID PASSAGE, A PLURALITY OF ROLLERS, MEANS FOR ROTATABLY SUPPORTING SAID ROLLERS ON ONE SIDE OF SAID PLATE SPACED AROUND THE CIRCUMFERENCE OF SAID PLATE, SAID ROLLERS ENGAGING SAID SHOULDER WHEN SAID PLATE IS INTERPOSED ACROSS SAID PASSAGE, A VALVE DISC, A PLURALITY OF LINKS FOR PIVOTALLY CONNECTING SAID VALVE DISC TO SAID PLATE, SAID VALVE DISC HAVING SEALING MEANS ON THE SIDE THEREOF FACING SAID SEALING SURFACE, SAID CHAMBER HAVING AN END WALL ADJACENT TO SAID PASSAGE, BUMPER