Patent GB-190218434-A (GB)
Title: Improvements in Pneumatic Hammers
Inventor: BURLINGHAM WILLIAM
Filed: 1902-08-21
Granted: 1903-04-30
Abstract: 18,434. Burlingham, W. Aug. 21. Percussive hand tools.-Figs. 1 and 3 show sections of one form of tool, Figs. 24 and 25 show sections of a modified form, and Figs. 21 and 22 shows two forms of handle. The tool has means for varying the opening of the throttle valve 11 and means for varying the point at which the supply of c o mpressed air &c. to the rear of the piston is cut off. The force of the blow may thus be varied. The piston 35 and annular main valve 19 are pressed constantly, the piston backwards and the valve forwards, by air acting on the shoulders 95, 96 respectively. For this purpose motive fluid is constantly supplied to the annular spaces 97, 6 through channels 7, 8, 9 and port 10 and through the channel 4, respectively. During the forward stroke, air reaches the rear of the piston through ports 20, 27, 29, as shown in Fig. 3. The space in front of the piston is always in communication with the outside air through ports 98. The main valve 19 between the cylinder 3 and the breech-piece 2 of the handle 1 is then moved to the right, as shown in Fig. 3, by air from the space 97. This passes through the port 40, channels 38, 39, port 33, channel 31, and port 34. The space behind the piston then communicates with the exhaust through ports 29, channel 26, and ports 28, 23, 30. The valve is next moved to the left to complete the cycle by putting the spa e in front of the valve in communication with the exhaust. This is done through the port 34, channel 31, ports 32, 41, and the annular space 36. The point at which the air pressing on the rear of the piston is cut off is determined by the ports 43, 44, 45, any one of which may be put into communication with the space 100, by turning the perforated tube 47 until one of the holes in it register with one of the ports 43, 44, 45. The head 16 of the tubular cut-off valve is thus pressed to the right, to cover the stem of the throttle valve 11, and thus stop the supply of fluid. The opening of the throttle valve may be varied by turning the screw 17. This valve is opened by the trigger 13 and closed by motive fluid passing along the channel 18. The piston and main valve are cushioned by extensions, such as 101, fitting into closed sockets. In the modification shown in Figs. 24 and 25, air enters by the channel 64, and during the forward stroke enters behind the piston 70 from the space 65 through the port 66 and channel 67. The valve 68 is shifted to the right by air passing through the ports 71, passage 72, ports 73, 74, and passages 75, 76. The space behind the piston then communicates with the exhaust through passage 67 and ports 79, 80, Fig. 25. Pressure on the shoulder 81 forces the piston to the rear, and the valve is again shifted to the left when the piston passes behind the port 83, a constant pressure acting on the shoulder 77. The extent of travel of the valve 68 may be varied by a screw 84. The piston and valve may carry packing-rings 87, 88. The cylinder 3, Fig. 1, and the breech-piece 2 of the handle are screwed together and are locked by a soft metal plug 52, Fig. 1, which is kept in place by slightly turning the parts 2, 3 after the insertion of the plug. Fig. 21 shows a form of handle where the grip 58 is connected by a spring strip 59 to the breech-piece 2. The parts 58, 59, 2 may be in one piece. Fig. 22 shows another form of handle to absorb shocks. The grip 61 has a stem carrying a disc 62 which moves in a chamber supplied on both sides of the disc with the motive fluid.