GB502348A - Improvements in or relating to screwdrivers - Google Patents

Abstract

502,348. Screwdrivers. BRADSHAW, G. Sept. 13, 1937, Nos. 24855, 24856, and 24857. [Class 61 (iii)] [Also in Group XXII] A screwdriver with a coupling element or screw, helical part 18 to engage a threaded recess 21 in the screw 20 and a clutch element 19 to drivingly engage a clutch part 22 on the screw, these elements 18, 19 in the form shown in Fig. 1 being carried by a bit 17 secured by a coupling member 16 to the tool proper, comprises a spindle 2 helically grooved at 3 for engagement with a nut 10 having ratchet teeth 11 normally urged by a spring 9 within a cap 8 into engagement with ratchet teeth 12 on the handle member 1. For driving the screw 20 the threaded part 18 of the bit 17 is engaged in the threaded recess 21 in the screw and when the handle 1 is moved forwards the spindle 2 is rotated causing the clutch element 19 to bind against the clutch part 22 on the screw and drive it into position. On the backward stroke of the handle 1 the ratchet teeth 11, 12 become disengaged, the nut 10 rotating idly and the spindle 2 remaining stationary Nut 10 may be locked by means of a lever 15 having teeth 14 engaging teeth 13 on the nut so that on backward movement of the handle 1 the spindle 2 is rotated to disengage coupling screw 18 from the screw 20. The modification shown in Figs. 4 and 5 comprise a threaded element 25 on the end of a spindle 23 having also. an enlarged part 24 slidably guided by a key 27 within a sleeve 26 and a rotatable handle 29 with helical cam surfaces 33 at its forward end separated by thrust bearing balls 34 from co-operating helical cam surfaces 32 on the rear end of the sleeve 26, a spring 28 forcing the handle and sleeve together. In operation screw 25 is engaged with the threaded recess 21 in the screw 20 to be driven and handle 29 is rotated causing relative forward movement of the sleeve 26 until the clutch surface 35 at the forward end of the sleeve 26 binds with the clutch part 22 on the screw 20. Fig. 7 shows a tool similar to that of Figs. 4 and 5 but adopted for attachment to the tool of Fig. 1 in place of the bit 17 and comprises the screw 46 at the end of shaft 43, sleeve 45 with clutch surface at the front end and sleeve 49 pinned to shaft 43, sleeves 45, 49 having co-operating helical cam surfaces 51, 52 and slidable sleeve 45 prevented from becoming detached by co-operating shoulders 47, 48. Fig. 8 shows a screw removing tool comprising a spindle 36 with screw coupling element 37 and enlarged left-hand threaded part 39 for a sleeve 40 having a conical dutch surface 42 at the forward end which may be of ratchet form and a knurled or milled operating flange 41. A similar device with a right-hand threaded sleeve is adapted for screwing in a screw. The device shown in Figs. 4 and 5 could be modified for removing screws by inclining the helical cam surfaces in the opposite direction. Specification 501,548 is referred to in the Provisional Specifications.