GB656582A - Improvements in or relating to pneumatic vibrators - Google Patents

Abstract

656,582. Compressed air engines; vacuum engines. KNIGHT, H. G. W., and BURGESS, P. Aug. 25, 1948, No. 22452. [Classes 122(ii) and 122(iii)] A pneumatic vibrator comprises a piston 19, 20 reciprocably mounted in a cylinder 12, a valve carried by the piston and having an operating member 22 reciprocably mounted in the piston and adapted to project from the cylinder to operate as a striker, means for supplying pneumatic pressure to one side of the piston to cause it to move against a spring 36 until the striker, and means for supplying pneumatic ted, whereupon further movement of the piston causes the valve 24 to be opened allowing the spring 36 to reverse the movement of the piston and the valve is subsequently closed. The cylinder 12 having a piston reciprocable therein is open to atmosphere at one end via perforated plates 29 and a felt sheet 30 and communicating with a source of vacuum at its other end through ports 16. A resilient disc valve 24 controls ports 21 in the crown 20 of the piston and is operated by a spindle 22 which is reciprocably mounted in the piston, extends through the bottom wall 15 of the cylinder and is attached to a striker 25. During downward movement of the piston due to vacuum on the underside thereof the valve 24 is closed until the striker 25 contacts the object 68 to be vibrated whereupon continued downward movement of the piston, which is limited by a stop 27 on the spindle 22, opens the valve 24, thereby equalizing the pressure on both sides of the piston, and allows it to be returned under the action of a spring 56, arranged between the piston and the bottom cylinder wall, to its upper position when the valve 24 is closed by being pressed against the perforated plate 29 and the cycle recommences. In a modification the upper point of reversal of the piston can be varied by positively arresting the valve 24 by means of a threaded spindle screwed through' the top of the cylinder and the valve is attached to a stem having a rod attached to the striker reciprocably mounted in a recess therein which recess also houses a spring so that the striker rod and the valve stem are urged apart and have relative movement. Specification 656,581, is referred to in the Provisional Specification.