GB190523617A - Improved Valve Mechanism for Pneumatic Percussion Tools. - Google Patents

Abstract

23,617. Pokorny & Wittekind Maschinenbau Akt.-Ges. Nov. 17,1904, [date applied for under Patents Act, 1901]. Percussive handtools.-In a valve mechanism for a percussive pneumatic tool, the differential valve 11, which has only one seating shoulder, has two sliding surfaces, and the fluid pressure supply is controlled by the outer edges and the exhaust by the neck. The supply passes along passage 16 and acts continually on the smaller end of the valve passing along the port 17 so as to drive out the piston 4, exhaust taking place through the port 24 and through passages 21, 22, the valve-neck, the passage 26, and the port 25 into the atmosphere. When the reduced neck 5 of the piston comes opposite the ports 19, 20, fluid pressure is communicated from the passage 16 to the larger end of tho valve which is consequently reversed. Fluid then passes also through the passage 18 into the space below the valve and into the passage 21 through the orifice 23, so as to return the piston, the exhaust passing through the conduit 17, the valve-neck, the passage 26, and the ports 25. When the end of the piston uncovers the port 20<1>, the pressure is exhausted from the lower end of the valve, which is returned. The Specification in the original form as published under the Act of 1901 comprises also a second valve mechanism for a percussive tool as shown in Fig. 3. Fluid pressure passes along the port 16 and the passage 27 and drives back the piston, exhaust passing through the port 24 and also through the passage 31, the valve-neck, and the ports 26, 25 into the atmosphere. When the piston closes in its rearward stroke the passage 31, the fluid enclosed between it and the valve causes the reversal of the latter. Fluid now passes down the passage 28 into the annular groove 29 and thence passes behind the piston, which is forced outwards, the exhaust passing out through the port 24 and also through the passage 27, the valve-neck, and the ports 26, 25. When the rear end of the piston passes the port 24, fluid pressure on the larger area of the valve is exhausted and the continued pressure on the smaller area forces down the valve. This subjectmatter does not appear in the Complete Specification as accepted.