GB1024340A - Improvements in or relating to a pneumatic hammer - Google Patents

Abstract

1,024,340. Fluid pressure hammers. MAR. TONAIR Ltd. Oct. 6, 1964, No. 40648/64- Addition to 868,771. Heading B3H. [Also in Division B4] A pneumatically-actuated hammer comprises a piston 15 movable in a cylinder 2 having an inlet and outlet port 30 at one end and a port 6 at the other end communicating with an air reservoir 1 which is provided with an inlet and outlet port 31, the arrangement being such that when air is fed through the inlet 30 and the port 31 is connected to exhaust, the piston moves until the port 6 is sealed by the piston and, upon subsequent reversal of the air flow, the air pressure in the cylinder drops below that in the reservoir so that when the seal between the port 6 and piston is broken, the pressure in the reservoir is applied to the entire area of the piston so as to cause a sudden outward stroke constituting a hammer blow. The piston is provided with a rod 10 for connection with a tool bit and also with a resilient ring 19 for sealing the port 6. In operation, with a control valve 32 in the position shown, air is fed through lines 33, 37 non-return valve 54 and port 30 into the cylinder to move the piston into the position shown, the reservoir being connected to exhaust via port 31, lines 36 and 34. Upon reversing the position of the spool 70 of the valve 32, air is fed to the reservoir, the air in the cylinder being exhausted via port 30 and a pressure regulating valve 50; the pressure-regulating valve is set so that the force acting on the inner side of the piston is greater than the force acting on the area of the piston defined by the port 6. In order to cause the piston to be driven on a hammer stroke a pulse of compressed air is fed via a valve 58 and port 56 to act on the top of the piston thereby breaking the seal so as to permit the full pressure in the reservoir to act on the entire area of the piston. The valve 32 may be operated automatically in synchronism with the movement of the piston as disclosed in the Parent Specification and the valve 58 may be operated automatically by a device responsive to the pressure in the cylinder or reservoir.