Patent GB-190219648-A (GB)
Title: Improvements in Pneumatically Operated Percussive Tools
Inventor: PAYTON WALTER
Filed: 1902-09-08
Granted: 1903-08-06
Abstract: 19,648. Payton, W. Sept. 8. Percussive hand tools; chisels. -A pneumatic percussive hand tool for chipping, caulking, &c., in which the valve is arranged axially within the piston, and the piston is of two diameters, the smaller and back end being always exposed to the live air &c., and the larger and front end alternately subjected to the pressure of the live air and to atmospheric pressure, is shown in Fig. 1. The smaller end of the piston works in a fixed sleeve D, and the larger end in the cylinder proper c. On the outstroke of the piston A, the air from the front end of the piston exhausts through the ports a, along the recess b in the outside of the valve B, through the holes a<2> into the space a<1>, and then into the atmosphere. On the instroke, air passes through the valve B, and ports a to the front of the piston, and escapes from the space a<1> into the atmosphere through a hole which is put out of communication with the space a' and into communication with small exhaust passages a<5> in the piston, when the latter nears the end of its stroke, and the air in space a' then acts as a cushion. The valve B is tubular, having its front end larger than its back end, and is provided with a collar b<1>, the space in front of which always communicates with the exhaust space a', while the space behind the collar b<1> communicates by the port a' with the exhaust space a' or the live air chamber c', according as the piston is at the outer or inner end of its stroke. In the former case, the air acting on the front end of the valve moves the valve towards the handle c<2>, and in the latter case the live air acting on the back of the collar b<1> moves it in the other direction, air being supplied through the hole b<2> to keep it in its foremost position until the port a<4> is opened to exhaust. The controlling-apparatus preferably consists of a piece e screwed into the handle and having a stopper e<2> at its upper end. Slots e<5> in the tubular valve E are made to register with slots e<6> in the piece e when the thumb-lever e<9> is depressed. The tool is made with a round end f and a hexagonal part F, which prevents the tool from rotating. According to the Provisional Specification, the front end of the valve may be closed and provided with lateral passages, which, in one position of the valve, coincide with the ports a, and the enlargement b<1> may be either near the centre of the valve, as shown, or at the front end of the valve, the spaces at the back and front of the enlargement b<1> then communicating at all times with the exhaust space a', and alternately with the spaces a', c' respectively or the valve may be arranged outside the cylinder, and such a valve outside the cylinder may be used for percussive tools in which the air is alternately admitted to and exhausted from the ends of a piston of one diameter. In order that air cannot be admitted to the cylinder until the tool is in its working position, the sleeve attached to the handle is made to side longitudinally on the end of the cylinder, and the sleeve and cylinder are provided with air ports which coincide when the tool is pressed to its work, but are moved out of coincidence by means of a spring placed between the ends of the sleeve and cylinder, when the pressure is taken off the handle. When the tool is to be used for riveting, it is provided with a sleeve or casing so that it may be extended by means of the motive fluid, in order to hold the tool between the work and a fixed frame or support.