GB773112A - An improved pneumatic spike extractor - Google Patents

Abstract

773,112. Spike extractors. SVENSKA TRYCKLUFTMASKINER S. A. SWALLERT & CO. June 29, 1955, No. 18771/55. Class 61 In a spike extractor comprising two jaws 23 pivoted on the outer end of a rod 11 fixed to a piston 10 operated by compressed air, the piston being enclosed in a cylinder 5 provided with devices for alternately connecting the chambers on both sides of the piston with a source of compressed air, a double armed locking lever 29 pivoted on the piston rod is provided with locking hooks 31, 32 to co-operate with corresponding teeth in the jaws, the hooks being arranged to lock the jaws in open and gripping positions respectively when the rod is retracted and protruded respectively. The piston rod and jaws are surrounded by a cylindrical casing 38 having an opening 39 through which the jaws may project. The jaws 23 are carried by semicircular discs 22, projections 26 on the discs engaging in slots 40, 41 in the casing. Two rows of teeth 27, 28 are provided in the upper edge of each disc, the locking lever 29 being curved to partly surround the upper portions of the discs. Upward movement of the rod 11 is limited by the projection 26 of one disc engaging the upper end of the slot 41, the projecting end Of the locking lever being limited by the upper end of the slot 40. The two jaws are locked in open position by the hook 31 engaging the rows of teeth 27. On downward movement of the piston the points of the jaws pass the bottom wall of the casing 38 and the projecting end of the lever 29 engages an abutment 43 in the slot 40 so that the lever is rocked and the hook 31 released. Thereupon the projections 26 of the discs engage the lower edges of the slots 40, 41 to cause the jaws to approach each other as the piston rod continues to move outwards. The jaws on reaching the position wherein they grip the spike are locked by engagement of the hook 32 with the rows of teeth 28.