GB799442A - Improvements in or relating to air-operated percussive tools - Google Patents

Abstract

799,442. Percussive tools. TURNER, S., and BAVERSTOCK, J. March 22, 1957 [Jan. 4, 1956], No. 363/56. Class 124. A pneumatic percussive tool, having a free piston in a cylinder and an air distributing valve with an actuating rod slidable lengthwise of the cylinder, the actuating rod and a bit holder being normally biased towards the work with the piston at the return end of the stroke and the bit holder clear of the actuating rod, is so arranged that pressure of the bit on the work moves the actuating rod and valve to admit air to the cylinder and cause the piston to strike a blow, the recoil of the cylinder restoring the valve and actuating rod to the normal position. As shown, the tool comprises a cylinder 10 having a piston 15, a head 14 at one end and a bit holder at the other. A valve 54 in the head admits air to a passage 37 leading to the piston cylinder in one position, and in another to a port 52 at the working end of the cylinder, a spring 60 biasing the valve to the latter position. A rod 55 attached to the valve 54 extends parallel with the cylinder and ends a short distance before a bit holder carrying, for example, type for marking billets. A rod 18 is slidably supported in a carrier screwed to the cylinder and is biased by a spring 17 towards the work. When the type is pressed against the billet, the rod 18 and the bit holder move against the spring 17 until the bit holder makes contact with and moves the rod 55 and valve 54 against the spring 60 to admit air to the cylinder and drive the piston forwards. The recoil of the cylinder is sufficient to move the valve back to its biased position and the cycle will be repeated so long as the type is pressed against the billet. The tool may be supported from an overhead beam and guided by handles 70.