GB972073A - Device for axial displacement of an elongated member - Google Patents

Abstract

972,073. Ratchet gearing. NITROGLYCERIN A.B. Jan. 30, 1961 [Jan. 29, 1960], No. 3416/61. Heading F2Q. [Also in Division E1] Ratchet mechanism for the axial displacement of a rod 28, in connection with the loading of bore holes with explosive, comprises a fixed upper clamping member 22 and a movable lower clamping member 24 which is connected with the pistons 58 of a fluid-operated actuator, the clamping members 22, 24 each comprising a housing 34 having a wall 30 of resilient material which is adapted to grip the rod 28 when fluid under pressure is supplied to a resilient annular housing 26 located within the housing 34. Control is effected automatically by a spool valve 66 and limit valves 102, 104 located at the ends of the stroke of the movable clamping member 24. The arrangement is such that whilst the rod 28 is being held by the upper clamping member 22, the lower clamping member 24 slides along the rod 28 to its lower position where it actuates the lower limit valve 104 thereby causing the lower clamping member 24 to grip the rod 28 and move it upwardly, the grip of the upper clamping member 22 being released. Upon reaching its upper position, the lower clamping member 24 actuates the upper limit valve 106 thereby causing the upper clamping member 22 to grip the rod 28 and the lower clamping member 24 to release its grip, the cycle then being repeated. By means of a pressure reducing valve 131 a reduction in the clamping power of the clamping member 24 may be effected. Also the upper clamping member 22 may be rendered inoperative by closing a valve 133 and resetting a valve 130. Under these conditions, the pipe 28 is given a downward step-by-step movement, slipping occurring during the upward movement. The pipe 28 may be brought downwards quickly by opening valve 133 and resetting valves 74 and 130. In a modification, an upper clamping member 24 is rigid with a piston 58 which is reciprocable with a housing 48 which is mounted in the wall of a bore hole 10 by a container having a resilient outer wall to which fluid under pressure is applied. The clamping member 24 carries the pipe with it during its up stroke and allows a sliding movement in the opposite direction. Specification 878,799 is referred to.