GB938601A - Improvements in impact wrenches and the like - Google Patents

Abstract

938,601. Screwing-up and unscrewing bolts &c. INGERSOLL-RAND CO. April 10, 1961 [May 6, 1960], No. 12889/61. Class 83 (3). A power operated impact wrench comprises an air motor 10, the spindle 18 of which intermittently drives a spindle 12 having a nut engaging socket 14. Air is supplied through a throttle valve 30 controlled by a trigger 32, to a passage 36, into a chamber 42, and thence to motor 10 via a valve 40, chamber 44, passage 46, and ports 132, 134. Valve 40 is biased into its open position by a spring 64, is exposed to atmosphere at 70, and is controlled by a spring-urged latch 72, axially and rotatably movable in bearings 74, 82. An arm 76, and a toothed dog 88, are non-rotatably mounted on latch 72, dog 88 being slidable on the latter, and a toothed wheel 84, engageable with dog 88, is rotatably mounted on a rod 78 keyed to spindle 12 at 80. Wheel 84 has a pin 110 which is urged into engagement with a stop 116, non-rotatably mounted on rod 78 by a torsion spring 118, and is rotated when a second pin 112 carried by a disc 114 fixed to rod 78, engages pin 110, as spindle 12 rotates. Motor 10 may be reversible, in which case a reversing valve 130 is provided, and valve 40, and therefore latch 72 can be rendered inoperative by a hand-operated spring-urged plunger 150 which engages a notch 148 in the valve, through an aperture 146 in a bush 144. In operation the angular position of pin 112 is chosen by placing disc 114 on the hexagonal end of rod 78, and valve 30 is closed, thus allowing spring 64 to open valve 40. Spring 94 pushes latch 72 to the right to engage valve 40, and the pressure of any air in chambers 42, 44, will be equalized by a bleed hole 166. Lever 32 is depressed to open valve 30, thus moving valve 40 inwardly to push against arm 76, and rotate the latter, bringing tooth 92 on dog 88, into engagement with teeth 86 on member 84, which has been rotated by spring 118 until pin 110 abuts stop 116. Motor 10 rotates spindle 12 and rod 78 until pin 112 contacts pin 110, whereupon the torque in rod 78 overcomes spring 94, and latch 72 moves axially to release valve 40, which then shuts off the air supply to motor 10, and the latter stops. A spring-urged plunger 98 presses against arm 76 on latch 72, and rotates the arm to disengage dog 88 from member 84, whereupon spring 118 rotates member 84 until pin 119 hits stop 116, ready for commencement of another cycle. It is stated that the wrench may be driven by an electric motor.