GB699051A - Improvements in or relating to rotary impact tools - Google Patents

Abstract

699,051. Screwing-up nuts etc.; tapping; drilling. INDEPENDENT PNEUMATIC TOOL CO. Oct. 2, 1951, No. 22918/51. Class 83 (iii). [Also in Groups XXIII and XXIV] A rotary impact tool comprises an anvil 56 having a pair of arcuate slots 66, a hammer 60 having openings 63 in which slide a pair of impact rods 64, a cam bush 80 fixed on a drive shaft 50 and a cam plate 70 having forked ears 69 engaging grooves on the rods. The cam plate is loaded by a spring 71 so that the impact rods are pressed forward into the slots 66 until increased resistance arrests the anvil and cam surfaces 79, 78 on the cam bush and cam plate withdraw the rods so that they each pass into the next slot 66 and, as the hammer 60 is speeded up by the acceleration of the electric driving motor 30 and the forward movement of the cam plate down the cam slope, deliver a hammer blow to the anvil 56 when they reach the end of their respective slots. A squared section 57 on the anvil carries a socket for engaging a nut or for carrying a screwdriver, tap, reamer, drill, sander, polisher or wire brush. A trigger 94, controlling the motor switch 97, may be locked in the on position by a plunger 112, and a rotatable ring 28 operates contacts for reversing the leads to the motor brushes so that the motor may be reversed. The motor shaft 26 carries a cooling fan 43 and its end is formed as a gear 46 engaging planet wheels 74 carried by a spider 49 on the drive shaft 50. To ensure alignment of the impact members, the flat inner sides of a pair of sectorshaped projections 87 on the hammer 60 engage closely with flattened surfaces 88 on the sides of the cam plate 70. The bearing supporting the anvil in the housing 20 and the bearings supporting the anvil and the hammer on the drive shaft allow a limited tilting movement of the anvil relative to the drive shaft.