GB754318A - Means for exerting longitudinal thrust on a column, caisson or the like - Google Patents

Abstract

754,318. Driving and withdrawn piles &c. UNITED STATES STEEL CORPORATION. Nov. 9, 1954 [Sept. 10, 1954], No. 32448/54. Class 68(2) In apparatus for driving or withdrawing columns or caissons, more particularly in establishing or removing a barge-platform for off-shore oil-well drilling, the lower gripper, mounted on the barge, comprises a casing with wedging-slips which grip the column, and the upper gripper comprises contractible friction gripper means, poweroperated thrust means on the barge being connected with the upper gripper to produce the required longitudinal movements. The gripper casing 19 is secured to a base plate 16 which is clamped to the deck 11 of the barge 10 by a plate 17, the caisson or column 15 being passed through the grippers and through a well 14 which extends from the deck to the bottom of the barge. The casing 19 has oppositely tapered inner surfaces 21, 22 which co-act with rings of segmental slips 24, 44 which are urged into jamming positions by springs 25. Compressible material is arranged between individual slips 24, 44. The upper slips 44 are supported, when inoperative, upon a ring 45 which is carried by the piston rods 42 of a number of peripherally spaced fluid-pressure cylinders 40. When the rods 42 are lowered, the upper springs 25 bring the slips 44 into operation, and the ring 45 pushes the lower slips downwards out of operation. The cylinders 40 thus permit the grippers 19, 25, 44 to be set for raising or lowering the caisson 15 relatively to the barge 10. The actual relative movement is effected by double-acting fluid-pressure cylinders 34 which are anchored at 35 to the plates 17, the piston rods 36 being connected to a friction gripper assembly 30. This consists of a rubber ring 32 fitted with segmental shoes 33 having serrated gripping faces. The ring 32 is accommodated in a metal body in such a manner that fluidpressure admitted at 31a contracts the ring and segments upon the caisson 15 which is gripped firmly. By contracting and releasing the ring 32 and actuating the cylinders 34, the gripper 30 takes a fresh gripping position on the caisson. either higher or lower, and the slips 24 or 44 are actuated to. hold the caisson between fresh positionings of the gripper 30, by actuation of the cylinders 40. In a modification, Fig. 7, the slips 60, 61 are thrust selectively against the caisson 15 by a wedging-ring 53 slidable within the casing 50 and actuated by a number of screws 54 driven simultaneously by a chain 57a. Aligned slips 60, 61 are connected by links 63. When the barge is raised to the desired height on the caissons, it may be supported by semi-permanent means, eg., bolted brackets, to relieve the slips.