Patent GB-1014081-A (GB)
Title: Power operated rotary impact tool
IPC: B25B21/02
Filed: 1961-12-14
Abstract: 1,014,081. Nut runners. S. B. MAURER. Dec. 14, 1961 [Jan. 11, 1961], No. 44795/61. Heading B3N. [Also in Division F2]  A rotary impact tool comprises a pneumatic motor 122, including a rotor assembly, a reaction shaft 118, a hammer 124, and an anvil 115, connected to the shaft by a lost-motion means. Shaft 118 is journalled in anvil 115 and has a flat 76, Fig. 5C, which co-operates with a pin 75 in the anvil, to thus allow relative rotary motion of approximately 80 degrees. The rotor comprises end plates 121, 123 and a cylinder 122, and these members are bolted to hammer 124. A sleeve 127 is keyed to shaft 118, and has a lug 128 which engages a valve plate 129 with lost motion. Cylinder 122 is divided into two pressure-tight portions 167, 168, by vanes 136, 137, vane 136 being carried by the cylinder, and vane 137 being carried in a slot in shaft 118. The latter is keyed to a hub 140 which is frictionally connected to a sleeve 143 by a rubber member 142 to form an overload clutch. Sleeve 143 has a bore which contacts rollers 144 carried by a cage 145, the rollers engaging the hexagonal end 147 of a bush 119, press fitted into housing 116. A reversing lever 154 carries a spring-urged detent 155, which is adapted to bias cage 145 either clockwise, or counterclockwise depending on the desired direction of rotation of the tool. In operation, air is admitted to a port 161, passes through conduits 162-166, to the bottom of vane 137, and thence radially outward between the vane and the side 134 of a slot into chamber 167. Chamber 168 is vented through exhaust port 171 in plate 123, port 170 being closed by valve plate 129. Pressure in chamber 167 tilts vane 137 to seal off side 135 and creates a counterclockwise torque on the rotor assembly, and a clockwise torque on shaft 118. Cage 145 is held in a counterclockwise direction, Fig: 5D, thus allowing sleeve 143 to  move only in a clockwise direction. Shaft 118 is effectively connected to the sleeve and therefore moves in the same direction, until flat 76 contacts pin 75, whereupon the torque is transferred to anvil 115. The rotor assembly moves in the counterclockwise direction until lug 128 vauses valve plate 129 to be shifted to the position of Fig. 6B, to close port 171 and open port 170. Chamber 167 is vented, and chamber 168 is sealed. The rotor assembly continues to move in the counterclockwise direction due to its kinetic energy until it reaches the position of Fig. 7A. Chamber 168 is pressurized, and chamber 167 is exhausted, to thus apply a counterclockwise torque to shaft 118, and a clockwise torque to the rotor. Shaft 118 is restrained from moving in the counterclockwise direction by the roller clutch 144. The rotor rotates until port 170 is again closed, the pressure builds up in chamber 167, but before appreciable kinetic energy is lost the impact blow is struck to drive shaft 118 in a clockwise direction until flat 76 again contacts pin 75. To operate the tool in reverse, lever 154 is moved to the position of Fig. 5D. Specification 1,014,082 and U.S.A. Specification 2,898,791 are referred to.