GB1352585A - Impact wrenches - Google Patents

Abstract

1352585 Impact wrenches NIPPON PNEUMATIC MFG CO Ltd 19 July 1971 [20 July 1970] 33834/71 Heading B3N A pneumatic impact tool comprises an air inlet port 21 having an air inlet valve 24 operable by a control member 19 and, an air passage 23 communicating with the inlet port 21 via the inlet valve and communicating with the inlet port 64 of an air motor 15 via a time delay valve 32. Control member 19 is operable via control piece 16 to open port 22 and allow air to pass into air passage 23. When control piece is released and member 19 is biased upwardly by spring 25, air passage 23 is connected to atmosphere via ports 27, 28 and 29. The time delay valve 22 is positioned in a chamber 30 and is biased to one end of the chamber by spring 35. Passage 23 is connected to the motor inlet port 64 via ports 38, 39, annular groove 37 and passage 40. In operation port 22 is opened to allow air to enter passage 23 and pass via ports 38, 39 to inlet port 64. Air also passes from passage 23 to air receiver 52 through a port 53. An adjustable needle valve 55 controls the rate of flow of air to the receiver 52. Port 54 connects receiver 52 to one side of valve 32. As pressure builds up the valve is moved against the pressure of spring 35. When the end of valve 32 passes port 52 the pressure acting on the valve rapidly increases to cause the valve to move quickly to an opposite end position in which air flow to the motor is stopped. A changeover valve 66 enables the motor to be driven in either direction.