Patent GB-118381-A (GB)
Title: Improvements in and relating to Operating Mechanism for Artificial Hands.
Inventor: PRINGLE ALEXANDER
IPC: A61F2/58
Filed: 1918-01-17
Abstract: 118,381. Pringle, A., and Kirk, T. S. Jan. 17, 1918. Limbs, artificial.-To enable the grip exerted by a hand to be increased as the hand closes, the operating-mechanism is arranged so that the cumulative effect of more than one movement thereof can be transmitted to the hand-operating wire or cord, and it may also be arranged that the leverage is increased as the hand is being closed. Fig. 1 shows operating-mechanism for applying a cumulative pulling action to the operating-cord due to several movements of the arm stump. The operating-wire 15 is connected to the pivoted arm 4 on which slides a rack 1 butting against the outer member of the operating-wire 15. The rack is slid step by step by a spring pawl 7<a> pivoted to the shoulder pad 6 to which is pivoted the arm 4 also connected to the stump sleeve 8, so that an inward movement of the arm stump causes the rack 1 to slide one step forwards on the arm 4. The rack can be released step by step by moving the arm stump outwards until a pin on the pawl 7<a> contacts a part of the shoulder pad and releases the pawl from the rack which is then left under the control of an escapement catch 13 carried by the arm 4. The release step by step is effected by further outward movement of the arm stump, the movement of the escapement catch being effected by an arm 14 pivoted to the shoulder pad; or the escapement may be controlled by a strap attached to the shoulder, arm, or other part of the body. The shoulder pad 6 has a triangular reinforcing frame of spring steel members held in position against the push of the lever 4 by body harness. In a modification, the mechanism is arranged in the small of the back on a pad secured to the body by a belt, the mechanism being operated by shoulder straps connected to the pivoted arm on which the rack slides and to the catch which moves the rack forwards step by step. In another modification, adapted to be arranged in the small of the 'back and operated by the shoulder movements, the operating-wire is secured to an eccentric grooved segment mounted on a pivoted sector with peripheral teeth to enable it to be operated step by step by a pawl pivoted to a lever operated by a shoulder strap. The grooved segment produces an increased leverage as the hand closes. To prevent the grooved segment, when released, from springing back too quickly under the pull of the hand-operating cord, a brake member with a friction pad to act on the side of the segment is provided and a similar friction pad is provided between the sector and the plate on which it is mounted. The brake can be released by a strap to give a quick return of the segment and wider opening of the hand. Fig. 6 shows the operating-wire 15 connected to the end of one of a pair of links 43, 47 which connect. arms 44, 46 operated by bearing-pads 45<a>, 46<a>. A pivoted rack 49 engages a pin on the arm 44. In a modification, the end of the operating-wire is connected to a pivoted disk with a notched periphery to engage the spring-pressed tooth of an operating- arm, a toothed segment being arranged on the underside of the rotatable disk to engage a detent pivoted to a fixed circular plate Fig. <8> shows the operating-wire 15 connected by a spring to one pivot 63 of the parallelogram links 65, 66, 67, 68, the links 65 being secured to a member 69 carried by the pad 70 and the link 66 being operatively connected to the pad 72. A pin 75 on the link 65 engages apertures in a spring quadrant 73 carried by the link 66, the quadrant being released by a backward pressure of the arm causing a pivoted member 76 to turn and press an arm 82 against the underside of the quadrant. In another modification, the end of the operating- wire is connected to a shoulder strap and a chest or arm strap and passes partly round an eccentric pulley pivoted on a plate connected to shoulder and body straps. A detent pivoted to the plate engages a ratchet wheel on the pulley. When the wrist joint is of the ball-and-socket type it is locked by the pulling of the operating-wire which passes through interchanging spigots and sockets on two parts which act as clamping-members on opposite sides of the socket on the forearm. The clamping may be effected by a bolt operated by the wire.