GB867602A - Improvements in screwdrivers and like torque transmitting tools - Google Patents

Abstract

867,602. Wrenches; screwdrivers. OAKES, B. E. March 31, 1958 [March 29, 1957 ; Sept. 11, 1957], Nos. 10269/57 and 28601/57. Class 61. In an impact screwdriver or wrench the body and tool head or bit are associated so that when the body is rotated in either direction without being subjected to a blow, the body and tool head or bit are locked together in such manner that the tool can be used as an ordinary screwdriver or wrench, the association being such that when the body is subjected to a blow, the body and tool head or bit are thereby unlocked to allow relative axial movement to take place therebetween. As shown the cylindrical metal body 10 has a striking block 11 provided with holes 12 for a tommy bar. A cylindrical shank 16 which .is slidable in the bore 13 of the body 10 is provided with a tool head which carries a screwdriver bit 13, the shank being urged outwardly of the. body by a compression spring 22. The shank is formed with four helical grooves 20, four helical ribs 21 being formed thereby. The four. grooves 20.are engaged by four dogs on a unit 24 secured in a socket 14 in the body 10. The unit 24 consists of a series of flat metal rings 25 secured as by brazing, each ring having four radially directed dogs 26 forming four helical ribs. A diametrical peg 34 is provided in the shank 16 ; the ends of the peg extend into opposite grooves 20 and normally rest on the set of rings 24. Each rib 21 is cut away at one flank to provide a seating 31 at the end of the cut-away 30 remote from the spring 22. When the tool is rotated to screw up a right hand screw the dogs 26 engage in seatings 31. On rotating the tool in the opposite direction the dogs 26 bear against the ends of the pins 34. Subjecting the block 11 to a hammer blow causes disengagement of the dogs 26 from the seatings 30 and downward movement thereof along the grooves 20. The sleeve 38 prevents the hand of the user from coming into contact with the shank. The second Provisional Specification describes, also a construction of locking means comprising a frictional pad associated with the sleeve the pad being moved radially into or out of gripping contact with the shank by rotation of the sleeve. A modification is also described in which the sleeve is rotated to move a stop peg into or out of alignment with the grooves.