Patent GB-1305701-A (GB)
IPC: A61F2/58
Filed: 1968-10-29
Abstract: 1305701 Artificial arms NATIONAL RESEARCH DEVELOPMENT CORP 29 Jan 1970 [29 Oct 1968] 51265/68 Heading A5R An artificial arm includes an elbow joint 11, Fig. 6, which comprises two pairs of four-bar chain linkages (61, 62, 63, 64), one pair attached to the forearm 12 and the other pair to the upper arm 10, each pair of linkages providing half the total relative angular displacement between the upper arm and the forearm about a pivot rod 65. The linkages at each pair are operated by a double-acting piston and cylinder assembly 60. The pivot rod 65 spans a frame 67 which provides a fixed link 61a (62a, 63a, 64a) Fig. 8 not shown, of each linkage and the piston 60a and the cylinder (60b) are connected respectively to crossmembers 68a (68b). Cranked links 61d (62d) of one pair of linkages are pivotted to the fixed links 61a (62a) and connected at pivots 61w (62w) to one cross-member 68a. Cranked links 63d (64d) of the other pair are similarly connected at pivots 63w (64w) to the other cross member (68b). Links 61b (62b, 63b 64b) are pivotal on the rod 65, the links 61b (62b) of one pair being formed as plates and being connected to the forearm 12 and the links 63b (64b) of the other pair being extended and connected to the upper arm 10. An actuation of the piston-cylinder assembly 60, the cranked links 61d (62d) of one pair of linkages are moved in one direction by the piston 60a thus moving the links 61b (62b) of the same pair in the same direction to pivot the forearm 12 about the rod 65. Simultaneously, the cylinder (60b) moves the cranked links 63d (64d) at the other pair and the links 63b (64b) in the opposite direction so that the upper arm 10 is pivotted about the rod 65 by the same angular amount but in the opposite sense to the angular movement of the forearm 12. The arm is connected through an abduction/adduction unit, Fig. 5, not shown, at the shoulder. The unit includes a plate 37 which is journalled in a support plate (32) Fig. 3B not shown, mounted on a telescopically adjustable tube 31 carried by a body harness (not shown). The abduction/adduction unit comprises a housing 39 which rotatable receives a cylinder 38 of the plate 37 and which is connected through balljoints and an adjustable telescopic link 54 with a crank arm 51 rotatable with a pinion 50 driven by a rotator (30) Fig. 1, not shown, mounted in the upper arm 10. A journal 55 supports the housing 39 and is pivotted at 56 on a non-rotatable bracket 57 of the rotator (30) so that as the pinion 50 rotates and alters the effective length of the link 54, the pivotting of the journal 55 on the pivot 56 causes abduction or adduction of the arm. A sprocket 41 is mounted for rotary movement with the housing 39 on a part-spherical bearing member 40 which is carried by the housing. The sprocket may be rotated about its axis by a chain 42 to rotate the arm relative to the plate 37, the ends of the chain being connected to piston-cylinder assemblies (45, 46, 47, 48), Fig. 4, not shown, controlled by compressed gas and one supported on each side of the tube 31. The sprocket 41 can tilt on the bearing member 40 in a vertical plane which includes the axis, of the sprocket to compensate for misalignment in lifting.