GB965516A - Improvements in or relating to impact wrenches - Google Patents

Abstract

965,516. Nut runners. FORGES ET ATELIERS DE MEUDON. Jan. 11, 1963 [April 27, 1962; Nov. 5, 1962], No. 1328/63. Heading B3N. A portable nut runner of the impact type comprises a tool holder having two opposite anvils, a carrier having a diametral passage, and an axial stub shaft rotatably driven from a motor, a pair of hammers radially slidable in the diametral passage, adapted simultaneously to strike the anvils, resilient means for urging the hammers inwardly to disengage them from the anvils, and a locking member rotatable with the tool holder and spring urged axially to lock the hammers in their retracted position, a flat face on the locking member being adapted to engage a circular cam face cut in the end of the carrier, to allow the locking member to lock the hammers, during slightly more than a half revolution of the carrier. The nut runner comprises a casing 30, Fig. 1, a reversible pneumatic motor controlled by a reversing knob 31, and an output knob 32, a splined motor shaft 34 engaging a splined bore in a hammer carrier 36, hammers 38, 39 in the carrier, a tool holder 51 having anvils 72 and a locking member 48. Hammers 38, 39, Figs. 1, 2, 3, are urged inwardly in a bore 65 in carrier 36 by a toroidal rubber ring 40 which engages grooves in pins 42, 43 carried by the carrier, and member 48 is rotatable with holder 51 through projections 54, 55 which also co-operate with a cam 66, 67 on the end of carrier 36 to move a face 64 on spring urged member 48 away from the hammers thus unclamping the latter. In operation member 48, Fig. 1, is moved axially by projection 55 and cam face 66, thus releasing the hammers, Fig. 3, which are moved outwardly by centrifugal force. Anvils 72 are held stationary by the nut to be tightened and as carrier 36 is rotated by the motor faces 73 on the hammers produce an impact on the anvils and therefore the nut to be tightened. The hammers are then moved inwardly by ring 40 and a disc 74, Fig. 7, which has cam faces 76 which engage pins 42, 43 and they are clamped by member 48 which has then moved axially. One blow is produced for each revolution of the motor. In a modification locking member 48 is replaced by two elements 48a, 48b, Fig. 24, which rotate relative to each other, but are relatively axially fixed, the hammers 38, 39 being locked by projections 82, 83, on member 48a, Figs. 41, 42, which engage elongated slots 88 in the hammers, and in this case the hammers are urged inwardly by ring 40 only.