GB115753A - Improvements in Artificial Arms. - Google Patents

Abstract

115,753. Troendle, H. Aug. 9, 1917. Limbs, artificial.-In an arm, the bending and extension of the forearm are due to the action of a connecting-rod having one end connected with the body of the bearer and the other end with a point on the forearm below the elbow joint; a releasable eccentric connexion is provided between the elbow-joint axle and the axis of the wrist, so that when the forearm is bent, there may be a corresponding bending of the hand on the wrist, while the hand may also be rotated by the bending movement of the arm through bevel-gearing, a tube serving to transmit this movement and also to accommodate the transmitting-device for opening and closing the fingers. The upperarm 1, Fig. 1, is pivoted to a saddle 5 secured to the shoulder by bandages 4, and the edge strap 6 of the saddle carries a journal box 7 for the upper end of a connecting-rod 8, of which the lower end is contained in a box 9 on the forearm 2, so that the arm is bent at the elbow when the stump is raised. Bevel-wheels 11, Fig. 4, loose on the elbow-joint axle 13, gear with a bevelwheel 12 on a tube 14 rotatable within the forearm. A double pawl 16 controlled by cords 17 from the sound shoulder may lock either bevelwheel 11 or may release both, the hand 3 being turned by the tube 14 when the arm is bent at the elbow-joint if either wheel 11 is locked. A rod 26 is eccentrically connected to the hand at 27 and to the elbow-joint axle 13 by a cross-piece connecting two flaps 25 on the axle, and teeth on parts controlled by the cords 17 are adapted to lock the flaps 25 to either internal teeth on rings 19 fixed to the upper-arm or to external teeth on disks 20 on the axle 13 and fixed to the forearm, so that bending of the arm either produces bending of the hand or not, as desired. The opening and closing of the fingers is controlled by a cord 38 connected at one end to a spring-controlled lever 29 and passing through the rod 8 to a connexion at the hip of the bearer. Raising of the shoulder thus causes upward movement of the lever 29 and of a sleeve 28 slidable on the tube 14 and carrying a spring pawl 37. The tube 14 has slots 33 through which extends a cross-bar 32 connected to the link 30 that actuates the fingers and carrying pawls 31 adapted to engage teeth 34 in the slots 33. Further pawls 35 are pivoted to the pawls 31, and when these pawls 35 have their lower ends touching one another, they are raised by the pawl 37 on the sleeve 28 and free the pawls 31 from the teeth 34, so that the cross-bar 32 may be lowered to open the fingers. At the next upward movement of the sleeve 28, the pawl 37 passes between the pawls 35, and the sleeve makes contact with the pawls 31 to raise the cross-bar 32 and close the fingers, the pawls 31 engaging the teeth 34 when the tension on the cord 38 is released, so that the fingers are locked in the closed position. The tube 14 terminates in a segmental head 43 on which turns a cup-shaped guide-piece 44 when the hand is being bent, the piece 44 being free to rotate on the axis of the forearm owing to the spherical shape of the wrist, which has openings for the controlling-parts 14, 26.