Slip-form jack

Claim 1

MOTOR DRIVEN HOISTING APPARATUS FOR USE IN CONSTRUCTING A CONCRETE WALL AND THE LIKE, PROGRESSIVELY UPWARDLY IN GENERALLY VERTICALLY EXTENDING SECTIONS, SAID HOISTING APPARATUS BEING COOPERATIVELY ASSOCIATED WITH A VERTICALLY EXTENDING CARRIER ROD ADAPTED TO BE ANCHORED IN AND EXTENDING UPWARDLY FROM A COMPLETED WALL SECTION, FOR RAISING SCAFFOLDING ALONG SUCH CARRIER ROD TO A LEVEL FROM WHICH THE NEXT WALL SECTION IS TO BE CONSTRUCTED, SAID HOISTING APPARATUS COMPRISING TWO VERTICALLY SPACED APART ROD-GRIPPING DEVICES EACH HAVING A TUBULAR GENERALLY CYLINDRICAL CASING CONCENTRICALLY SURROUNDING SAID CARRIER ROD WITH PLAY AND FORMING A RADIAL SPACE THEREWITH, AT LEAST TWO VERTICALLY EXTENDING FLUID PRESSURE CONTROLLED RAISING DEVICES SYMMETRICALLY DISPOSED WITH RESPECT TO AND RADIALLY SPACED FROM SAID CARRIER ROD, EACH RAISING DEVICE HAVING A TELESCOPING DRIVE COMPRISING A CYLINDER AND A PISTON MOVABLY DISPOSED THEREIN, MEANS FOR ARTICULATELY LINKING THE PISTONS OF SAID RAISING DEVICES WITH THE CASING OF ONE OF SAID ROD-GRIPPING DEVICES AND MEANS FOR ARTICULATELY LINKING THE CYLINDERS OF SAID RAISING DEVICES WITH THE CASING OF THE OTHER ONE OF SAID ROD-GRIPPING DEVICES, MEANS FOR ALTERNATELY SELECTIVELY CONVEYING PRESSURE FLUID RESPECTIVELY TO THE TOP AND BOTTOM OF THE CYLINDERS OF THE RESPECTIVE RAISING DEVICES TO EFFECT THE RAISING OPERATION THEREOF, AND MEANS IN THE RESPECTIVE ROD-GRIPPING DEVICES OPERATIVELY RESPONSIVE TO THE RAISING OPERATION OF SAID RAISING DEVICES FOR CAUSING THE CASING OF THE UPPER RODGRIPPING DEVICE TO ANCHOR ITSELF TO THE CARRIER ROD WHILE THE LOWER ROD-GRIPPING DEVICE SLIDES UPWARDLY THEREALONG TO A HIGHER LEVEL, SAID LAST NAMED MEANS COMPRISING A PLURALITY OF CLAMPING RINGS DISPOSED WITHIN THE RADIAL SPACE FORMED BY THE CASING OF EACH ROD-GRIPPING DEVICE WITH SAID CARRIER ROD, MEANS PROJECTING RADIALLY INWARDLY FROM THE WALL OF THE RESPECTIVE CASING FOR HOLDING SAID CLAMPING RINGS ON ONE SIDE THEREOF, AND SPRING MEANS ACTING RESPECTIVELY AGAINST SAID CLAMPING RINGS ON THE OTHER SIDE THEREOF FOR HOLDING SAID CLAMPING RINGS NORMALLY IN AN ANGULAR POSITION WHICH DETERMINES THE DIRECTION IN WHICH THE RESPECTIVE ROD-GRIPPING DEVICE IS TO BE RESPECTIVELY ANCHORED TO THE CARRIER ROD OR IS TO BE SLIDABLE WITH RESPECT THERETO.