GB188061A - Improvements in or relating to pressure fluid operated hammers for use in pile extracting and similar operations - Google Patents

Abstract

188,061. Hiley, A. July 29, 1921. Combined fluid-actuated and mechanical gears. - In a pressure-fluid operated hammer for pile-extracting and like operations, the valve controlling the admission and exhaust of the pressure fluid is moved to the inlet position by mechanical means comprising a pivoted member projecting through the cylinder wall and operated by the ram of the hammer on its downward or idle stroke, and the valve is moved to the exhaust position by pressure fluid admitted through a port uncovered by the ram near the end of its upward or power stroke. An arm D, pivoted to a block D<2> capable of adjustment parallel to the axis of the ram A', projects through an opening in the wall of the cylinder B, and lies in the path of a shoulder on the ram, and pivoted to the arm is a rod d, the lower end of which operates the stem c of the piston valve C with a certain amount of lost motion, a buffer pad d<1> being preferably interposed. A spring d<2> normally holds the rod d out of contact with the valve stem c. At the end of the upward or power stroke, the ram uncovers a passage c<2> through which pressure-fluid is admitted under the piston C' of the valve C, which is thus moved upwards to exhaust fluid from the cylinder B through the ports C<3>, C<4>. The ram A<1> then rebounds and falls by gravity, and the fluid under the piston C' exhausts through the passage c<2> now uncovered, while the valve C remains in the exhaust position owing to friction. When the shoulder of the ram A' strikes the arm D, the valve C is moved downwards, and the port C<3> is put into communication with the pressure port C<5>, admitting fluid to the cylinder B under the ram which is thus driven upwards. The adjustable block D<2> enables the point of admission to be varied to give a cushioning effect.