GB122849A - Improvements in and relating to Screw-drivers. - Google Patents

Abstract

122,849. Lundmark, J. Jan. 27, 1919. Screwdrivers.-In screwdrivers of the kind provided with a gripping device for holding the screw while it is being driven, the gripping device comprises a pair of jaws flexibly connected together and slidable on the driver and controlled by a member also slidable on the driver and moved in one direction manually to open the jaws to engage the screw, and in the other direction by a spring to close the jaws to grip the screw. The jaws may be constructed to grip the screw by its head and also at one or more points along its length. In one form, Fig. 2, the jaws 8 are connected by a spring 11 tending to open them, and are provided with slots 7 for the passage of pins 5 and 9 connecting the arms of the controlling member 4. The pins 5, 9 also pass through a slot 6 in the driver 1, and the pin 5 is provided with guide flanges or projections 14. A spring 3 normally presses the member 4 and, with it, the jaws 8 towards the handle of the tool, so that the point of the driver projects beyond the jaws, and the tool may then be used as an ordinary screwdriver. In operation, the member 4 is pushed forward against the spring 3, the pin 5 engaging the outer end of the slots 7 and pushing forward the jaws 8 which open out by the action of the spring 11. The screw is then inserted between the jaws 8 and the member 4 released to allow it to be retracted by the spring 3 and by the engagement of the pin 9 with the inner ends of the slots 7 to withdraw and close the jaws 8 to grip the screw 12 and hold it firmly in engagement with the point of the driver, as shown. When the screw is driven in so far that the jaws 8 engage the work, the jaws are automatically pressed apart to release the screw and are fully retracted by the spring 3. In a modification, Fig. 5, the jaws are provided with two or more sets of notches 15, 16 to hold the shank of the screw 12 as well as its head, the jaws on meeting the surface of the work releasing the screw head from the first set of notches 16 and re-engaging it with the next set 15, finally releasing the screw as in the construction shown in Fig. 2. The jaws 8, Fig. 5, are provided with inclined surfaces 17 adapted to be engaged by the arms of the member 4 to close the jaws against the action of the spring 11, and this spring is .shaped to engage frictionally with the sides of the driver 1 so that the jaws do not move forward with the member 4 until the pin 5 engages the end of the slots 7, thereby ensuring the opening of the jaws by the spring 11 to receive the screw. Thumb projections 21 are provided on the member 4 for actuating it.