GB1287175A - Torque control impact wrench - Google Patents

Abstract

1287175 Impact wrenches INGERSOLLRAND CO 25 Sept 1970 [2 Oct 1969] 45832/70 Heading B3N A rotary impact wrench comprises a motor 7, a rotary impact mechanism 9 and a spindle 12, there being a resilient torsion member 17 between the impact mechanism and spindle adapted to transmit a torque load and to yield in response to said torque load, a rigid member 33 for winding and holding said torsion member to apply a predetermined preload to it preventing it from yielding further until the torque load on the member rises above said preloaded value of torque and an arrangement for creating a signal in response to further yielding of said torsion member and a valve 37 operative in response to said signal, to stop said motor. An anvil 11 has a tubular portion 15 and the inner end 18 of the torsion member rigidly connected thereto. The lower end of the torsion member is rigidly connected to the spindle 12 and has two wings 21 positioned in slots 26 of a tube 25. Tube 25 has splines 30 which are also provided with a thread 31. Portion 15 has splines 29 and there is a sleeve 33 mounted on the portion 15 and tube 25. A nut 34 on tube 25 can be moved upwardly to cause anticlockwise twisting of the torsion member 17. This twisting causes ports 23 in the member 17 to be sealed against the sides of slots 26. In operation, these ports are kept sealed until the impact load torque exceeds the predetermined preload on the member 17 which causes further anticlockwise twisting of the member thus allowing the ports 23 to be vented. This causes a signal to pass along passages 20 and 47 to valve 37 which operates to cut-off the air supply to the motor. The nut 34 can be locked to sleeve 33 and is operable by a chuck key 55. In another embodiment, Figs. 6 and 7 (not shown), the torsion member is positioned between the motor and the rotary impact mechanism.