GB190405818A - Improvements in or relating to Pneumatic Percussive-tools. - Google Patents

Abstract

5818. Boult, A. J., [Imperial Pneumatic Tool Co.]. March 9. Rock drills.-The valve 8 of a pneumatic tool for drilling &c. is annular, with one end closed, and works between a part of the cylinder barrel or a separate bushing 7 and a four-grooved valve box 6. When the valve is in the position shown, air passes through the passages and ports 20, 19, 12, 16, 13 to the front of the piston 11 and exhausts through the ports 18, 17 and the groove 14. In the other position of the valve, air passes through the ports 16 and round the back end of the bushing 7 to the back of the piston, and exhausts from before the piston through the grooves 15, 14. Near the end of the out-stroke, the piston uncovers the port 37, and live air passes to the back of the valve and moves the same ; near the end of the return stroke, the piston groove 42 puts the port 37 in communication with the passage 41 and exhaust groove 14, and, when the piston closes the ports 18, the cushioned air moves the valve. The annular space in front of the valve end 9 communicates with the atmosphere by a hole 43. The supply of air is controlled by a thumb-lever and by a screw - plug 23 which is slotted at 21 and serrated to be engaged by a spring catch 24.