Patent GB-171015-A (GB)
Title: Improvements in and relating to artificial hands
IPC: A61F2/58
Filed: 1920-09-23
Abstract: 171,015. Betti, U., and Strata, C. Sept. 23, 1920. Limbs, artificial.- Comprises a construction of an artificial hand of the type in which the thumb and articulated fingers are operated by the rotation of a shaft journaled in the hand and connected to the fingers and thumb by link-work, the shaft being, in general, rotated by movement of the elbow-joint. Means are also provided in the present construction for permitting movement of the fingers and thumb independently of movements of the elbow-joint, and for locking the fingers &c. in desired positions. Upper and lower portions A, B of the artificial arm are pivotally connected at 6, and a hand portion C is rigidly secured to the forearm portion. The sections of the fingers are interconnected by links, the lowest sections being connected by links 36, 37, 38, 39 to lever arms 31, 33 formed on blocks 29, 30 secured to a rotatable square spindle 28. In another projection 32 of the block 29, slots are formed in which engage pins 41, Fig. 2, projecting laterally from a block 42 slidably mounted on a vertical rod 43 carried bv a fixed bracket 44. Depending from the block 42 is a link 45 which is mounted in a guide 46 on the bracket 44 and which carries, at its lower extremity, a pin 47 which engages a slot 48 in the end of a lever arm 49 fulcrumed at 50 to the bracket 44 and pivoted, at its other end, to a rod 51 which is slidably mounted in a bracket 52 carried by the hand casing and between which and an adjustable collar 53 is mounted a spring 54. Projecting from the block 42 is a pin 55 whereon is mounted one .end of a control rod D comprising links 56, 60, the other end of which is connected to a pin 64 carried by a crank 65 fast with the upper arm portion A. Teeth 57 are formed on the link 56 which also carries a pin or screw 63 and a frame 58 wherein is mounted a spring-controlled bolt 59, engaging a notch 66 in link 60. The link GO is slidably mounted in the frame 58 and has slots 61, 62 at either end for engagement with the pin 63 and to connect the link 60 to the pin 64 allowing a certain lost motion between the link 60 and the crank 65. A nut 68 secured to the interior of the casing 7 carries a screwed spindle 67 carrying a lever 69 loosely mounted thereon and a lever 70 securely mounted thereon. A toothed sector 71 on the lever 69 engages the teeth 57, and a cam 72 on the lever 70 engages the catch 59 to lift it out of engagement with the notch 66. The spring 54 tends always to depress the lever 49 and thereby, through the link 45, to maintain the block 42 at the top of the guide-rod 43 and thus to keep the fingers and thumb closed. .On bending the elbow-joint, the catch 59 is first caused to engage the notch 66, thereby locking together the rods 56, 60. Subsequent straightening of the arm draws the block 42 downwards, thus turning the levers 31, 32, 33 to unclench the fingers and thumb against the spring 54. To lock the fingers and thumb in any desired position, the spindle 67 is screwed down hard into the nut 68, thereby gripping the boss of lever 69 between its own boss and the casing 7 to secure the same, with the control rod D and the handoperating mechanism in any position in which they have been set. By turning the lever 70, the cam 72 is caused to lift the catch 59 from the notch 66 and thereby to disengage the links 56, 60 and to allow free movement of the elbowjoint to an extent limited only by the length of the slots 61, 62. To operate the fingers without moving the elbow joint, the lever 69 may be rotated and thus, through the engagement of the teeth 57, 71, the control link 56 and block 42 are moved. In a modification in which the fingers and thumb are not normally closed, the control spring 54 is housed within a telescoping control rod, which replaces the links 56, 60.