GB323035A - Improvements in or relating to screw or nut driving devices for portable, power driven, rotary tools - Google Patents

Abstract

323,035. White, A. E., (Independent Pneumatic Tool. Co.). Sept. 13, 1928. Bolts, nuts, and screws, screwing-up and unscrewing; yielding-drive attachments.-In portable power driven machines or attachments for screwing- up or unscrewing nuts, screws &c., a tool-spindle is rotatably supported in the driving shaft of the machine and is driven therefrom through two clutches whereof one i s adapted to slip when the nut &c. is screwed home. In an electrically driven machine the armature shaft 6 drives the main shaft 4 through triple reduction gearing 11, 9, 7 enclosed in a casing 2. The shaft 4 has an axial bore in which is slidably and rotatably mounted the tool-spindle 12 which carries a removable spanner 45 or a screw-driver &c. For right and left hand screwing the tool 45 is secured by a keyed connection instead of the screw-thread shown. The spindle 12 has a clutch part 23 slidably keyed thereto by means of three sets of balls 24 kept in position by a washer 32 pressed upwards by a spring 31 which engages an adjustable abutment 33 on the spindle. The clutch part 23 is normally pressed by the spring 31 into engagement with an intermediate clutch part 16 rotatably attached to the spindle by balls 18, and having clutch teeth 17 on its upper surface corresponding with teeth 14 on a clutch part 13 attached to the shaft 4. A spring 37 in the bore of the shaft 4 normally maintains the clutch 13, 16 disengaged, with a part 23 resting on a flanged part 42 of a casing 41 attached to the gear casing 2. In operation, with the parts in the positions shown in the figure, the friction of the clutch 23 on the flange 42 prevents the spindle 12 from being rotated by the motor and the tool 45 may be engaged on the nut &c. Pressure on the device then engages the clutch 13, 16 and the tool is rotated until the nut is screwed home, whereupon the clutch parts 16, 23, whose teeth are bevelled more acutely than the teeth 14, 17, are separated against the pressure of the spring 31. The clutch parts 16, 23 continue to slip and give an audible signal until the device is removed from the work, some clearance being provided between the teeth and recesses of the clutch to allow blows to be imparted to the tool without imposing the) full torque of the motor on the operator. The spaces in the clutch 13, 16 are considerably larger than the teeth in order to facilitate complete engagement.