US2516791A - Artificial arm - Google Patents

Description

July 25, 1950 s. M. MOTIS ETAL ARTIFICIAL ARM 3 SheetsSheet 1 Filed April 6, 1948 JOS'EPH 0. CHHPMHN INVENTORS GILBERT M. M0776 QTTOBNEV July 25, 1950 cs. M. MQTIS ETAL ARTIFICIAL ARM 3 Sheets-Sheet 2 Filed April 6, 1948 O O b m! ON 3\ hm HTTOB/VEV m m 7 m 0 H m MHV .CW p T 2H EP 6 mm Patented July 25, 1950 ARTIFICIAL ARM Gilbert M. Motis, Burbank, and Joseph 1). Chapman, Inglewood, Calif., assignors to Northrop Aircraft, Inc., Hawthorne, Califi, a corporation of California Application April 6, 1948, Serial No. 19,375

9 Claims.

. I ,The present, invention relates to artificial arms, and its primary object isto provide an arm havinga wrist unit embodying passive, or manually pre-set fiexion and extension of the wrist, together with automatic supination of the wrist driven member responsive to fiexion of the forearm. More specifically, one of the objects of the invention is to provide a wrist unit having provision for both. fiexicn-extensicn and pronationsupination movements, and in which the pronation-supination movement takes place beyond, or .distally from the fiexion-extension axis. This is the ,exact reverse of the arrangement employed in all prior devices of like nature known to us, and results in certain advantages which are impossible of attainment with the prior devices.

With the present invention, the wrist unit consists of a first member which is pivoted on the forearm component for swinging movement about the flexion-extension axis, and a second member which is journaled on the first memher for rotation about the pronation-supination axis. Flexion and extension movements are passively, controlled; i. e., the aforesaid first member ofthe wrist unit is adjusted angularly with respect to the forearm by using the other hand, or by pressing the same against the body or some stationary object such as a table, chair, or the like.- When the wrist has been adjusted to the desired degree of fiexion, the unit is locked and remained in fixed angular relationship to the forearm centerline until readjusted.

Pronation and supination movements of the wrist unit are coupled to forearm fiexion, and are accomplished by means of a force-transmitting system ,which connects the rotatable memberof the wrist to the upper arm component. This force-transmitting system is so constructed and arranged that when the forearm is flexed, the, rotatablemember of the wrist unit is automatically turned in a manner closely approximating the supination of. the natural Wrist. Since the rotatable member of the wrist unit is journaled on the swingable first member, fiexion of the latter causes the supination axis tobe positioned at an angle to the forearmcenterline, and thehookor hand is thereafter caused to rotate about the inclinedaxis. When the wrist unit is thus positioned with a predetermined amount of fiexion'the coordinated supination of the wrist member about the inclined axis as the forearm is flexed produces a leveling action at the hand or hook, en ablingan eating utensil to be held level while 'itis being raised from ,the

table to the mouth. .This self-leveling action greatly facilitates ,the process of eating, as well as the performance of other acts such as smoking, shaving, and the like, wherein the hand is raised to the face. Such self-leveling action cannot be obtained in prior devices having the fiexion-extension axis located beyond the point at which supination begins, as this latter arrangement merely causes the flexed wrist and hand to be swung in an arcuate path about the fixed supination axis. I

Another important object of the invention is to provide an artificial armwhaving-a rotatable wrist member coupled to. the upper arm component, whereby the wrist .is supinated when the forearm is flexed; together, with means for interrupting the drive to the wrist member and simultaneously lockingthe latter againstrotation, so that the hook or hand-can be selectively locked in any angular, position about'the pronation-supination axis. V

Still a further object of the invention is to provide an arm of the class described, wherein the force-transmitting control member which operates the associated hook or hand passes through and is confined to a pointrepresenting the centerv about which all supination and fiexion movements take place. By thus confining the path of the control member to thefcommon center for both directions of movement of the wrist, the effective, distance, between the ends of the control member is held .constant at all times, and operation of the hook or hand is not affected by the position. of the same about either of its axes.

The foregoing and other objects and advantages'of the present invention will become apparent to those skilled in the art upon consideration of the following detailed, description of the preferred embodiment thereof, reference being had tothe accompanying drawings, wherein:

Figure 1 is a partially broken away perspective view of an extended arm embodying .the principles of the presentinvention;

Figure 2 is a ,cut away side view of the same;

Figure 3 is a view similar to Figure 2, but with the forearm flexed, and the, wrist unit turned on its pronation su'pination axis; I

Figure 4 isa sectional top plan view ,of the arm, as taken along the line '4-4 in,Figure 2;

Figures ,is a-slightly enlarged sectional view taken along the line 5.-5 in Figure3;

Figure 6 is a fragmentary top plan view of the wrist unit and hook, showing-the same in three positions ,of fiexion;

Figure 7 is an enlarged sectional view taken along the line 'l'| in Figure 4, showing the wrist unit coupled to forearm flexion;

Figure 8 is a view similar to Figure 'l, but showing the wrist unit disconnected from the upper arm component and locked against rotation; -l.

Figure 9 is an enlarged sectional view taken along the line 3-9 in Figure 4.

In the drawings, the reference muneral l designates the artificial arm in its entirety, said arm comprising an upper arm component H, to which a forearm component [2 is connected by an elbow joint l3. Mounted 'on the outer end of the forearm member 12 is a wrist unit M, the distal end of which is formed with an attach plate l that is adapted to receives. hook unit "5. In the embodiment illustrated, the upper arm component I 1 consists of a stump socket l3 which is preferably made up of laminated plastic-impregnated'fabric, formed to receive the stump in a snug-fitting engagement. The lower end of the stump socket l9 ismolded over and bonded'to an annular flange on a housing forming a part of the elbow joint unit 13. The elbowunit I3 is the same as that disclosed in the copending application of Meyer Fishbein, et al., S. N. 747,690, filed May 13, 1947, to which reference may be had for details of construction and operation. I 3 The-housing 201s generally cylindrical in shape, with a spherically curved outer end portion, and flats 2| formed on opposite sides thereof. A saddle 22 is mounted on the upper end of the forearm member I2, and has two laterally spaced ears '23 which are disposed to lie against the flats 2|.

Extending through the housing 23 and journaled suitable bearings therein is a hinge pin 24, the ends of 'which project from the flats 2i and are rigidly connected to the ears 23. Inside the housing 20 is a locking device (notshown) for locking the forearm member in any one of a large number of closely spaced angular positions relative to the upper arm component H. i

v The saddle 22 is semi-cylindrical in shape, and embraces the bottom half of the housing 20. flange 25 project from the outer end of the sade dle 2'2; and bonded to the flange is :a forearm shell '26, preferably of laminated plastic-impregnated fabric. An opening 21 is cut out of the top portion of the shell 26 adjacent the elbow joint to provide clearance for the housing 20 when the forearm member is flexed, as shown in Figure 3. At its outer end, the forearmfshell126 fits over and is bonded to an annular flange 30 projecting rearwardly from the back of a ring shaped memher 31. Projecting forwardly from the top and bottom edges of the rin 31 are tongues 32 and 33 which provide support for the wrist unit M.

The wrist unit [4 consists of a housing 34 which is pivoted on the forearm component [2 for angular movement about the fiexion-extension axis, and the attach plate 15 that is journaled on the housing 34 for rotation about the pronationsupination axis. For the purposes of thepresent invention, the wrist-flexion-extension axis is considered to be disposed at right, angles to the elbow hinge axis; while the pronation-supination axis extends generally forwardly from the flexion-extension axis and is perpendicular, thereto. When the'w'rist unit [4 is straightened out, the prone.- tion-supin ation axis substantially coincides with the longitudinal centerline of the forearm "component I2, and when the wrist member 34; is swung around on the flexion-extension axis, the pronation-supination axis swings with it. Flexion 4 is the bending of the wrist to move the hand or hook toward the body; while extension is the 0pposite movement, tending to straighten the wrist, or move the hand away from the body. Pronation is the turnin of the hand to a palm-down position; while supination is the turning of the hand to :a palm up position.

The hinge connection forming the fiexion-extension axis of the wrist includes two vertically spaced tongues 36, 31 which extend rearwardly from the member 34 and overlap the tongues 32, 33, respectively. A pivot pin 40 is inserted into a hole in the top tongue 32 and is held therein by a set screw 39, said pin being journaled in a bushing 4| in tongue 36. In axial alignment with the pin 40 is another pivot pin 42 which is inserted into a hole in the bottom tongue 33 and is journ aled in a bushing 43 in tongue 31. The pin 42 is held against turning by a set screw 44 (Figure 9) that is threaded into a tapped hole in a boss 45 formed on the inside surface of the tongue 33. Thewrist housing 34 is adapted to be-locked in any one of several angularly spaced positions of flexion, and to this end a bifurcated locking lever 46 is pivoted at 41 on :a blade-like projection 50 extending upwardly from the top end of pin 48. The lever 46 extends-longitudinally 0f the wrist housing 34, and its rear-end is pivotally connected at 5! to the head 52 of a pin 53 which is disposedwithin a hole 54 in the tongue 36. The bottom end of-the pin 53 normally projects below the tongue 315 and is adapted to seat in an one of several holes 55 formed in the tongue 32,;said holes being arranged in :a circular arc about the axis of pin 40. In the preferred embodiment illustrated, there are five of the holes 55, the middle one of which gives a straight-out position for the wrist, and the others giving positions of 22 and 45 degrees of flexion or extension to either side of the straight-out position. A spring 56 bears upwardly against the freeend of the locking lever 45, urging the same into locking engagement.

The outer end of the cylindrical wrist housin 34is threaded internally at fill to receive the threaded barrel 6l of an annular bearin sup port member 62. Pressed intoa cylindrical seat 63 in the member 62 isthe outer race '64 of ball bearings 65. The inner race 66 0f the ball bearings is mounted on the outer suriiace 'lfl'of an annular flange 'llgprojecting rearwardly from the back of the attach plate l5 The inner surface of the flange H is threaded at 72 to receive a locking ring 13, the back end of which is provided with a radial flange 14 that engages the inner race 66 to clamp the latter inplace.

Projecting rearwardly from the'back side of the attach plate I5 through the center or'uie locking ring 13 is a tubular extension 15 having a central bore 16 formed therein. The tubular extension 15 might be formed integrally with the attach plate, as shown, or made as a separate part to facilitate manufacture. A sleeve bushing 30 is pressed into thebore '16, and slidably-dis-J 'posed'within the bushing is a cylindrie al coupling member 8!, the outer end of which is formed with a socket '82 that 'is adapted to r e ceijve a companionate couplingmember on theliool; 16 so as to provide an operating connectioii there with. Thecoupling memberjal has pins]?! pro- Jctin re l 'l m e l i s d s t e f and ns t. gi s sl i ehg u v rtsndifie grogvs. 1 in F b h ng w om th QQUPl member against turning,

fflh hook it websi is .da i a iy mounted on'the-outer-faceof theattach plate It,

- outer face of the attach platelli. 1.;A-hook;control coupling member- ;(not shown) projectsfrom the vback face of the .coupling-.plate.1l.4 .andis :adapted .toseat in: the socket-.82. of the coupling :member. 8 I v as. the coupling .p1ate.34-.approaches full zseating engagement withv -the::-attach:.=p1ate-..I 5.; .and :theci u said coupling members are thereafter connected togethertomovei 'as oner-c Thea-coupling member -on the unit IIi:isoperativelyconnected to apiv- .oted. hook 86,-.and. causes =.the lattertto ;;be -closed against a stationary :hookvll. I whenzthelinterconz: 15

- nected coupling. members were movedaxially toward the right in the bore;-of-.-bushingz.80. l!l2he mechanism for actuating that pivoted :hookaBB forms no part of thepresent-invention, and therehereln; .s s, A control wire90 ;is-;attached-.-1n anysuitable manner to the inside. of the coupling member 8| and extends rearwardly therefrom through the bushing 80 into the forearm shell n. The rearend of the wit-e90- is' trained over the top of a small pulley 9I formed-in.oneendofwahub:92 which is journaledrfor rotation on..-a transversely disposed tubular support 93. The tube 93 is held at its ends by two insert members 94 and 945-);30

which are embedded in the side walls of theshell 26. One end of'the tube 93"has a splined; connection at 95 with the member 04?, thereby-locking the tube against rotation;

. Projecting radially *from the. hub- 92 alongsideadm the small pulley 9| antarm having apin-'91 extending through .a. holein its-router end. A fitting I00 attached to'the end of control wire 90 .is engaged on one projecting endof the .pin 9.1,

to form an anchorage for thezwlrei The-Othemsm end of the pin- 91'projectslaterally-from the opposite sideof the-arm Stand. is engaged by. one end of a spring IOI; the other end of the. spring being anchored to a-screww I02 which extends through the shell 28 and flange-25 of the-saddle 22. The spring-IOI pullsnonrthearm 96, exerting a counterclockwisetorque onthehub. 92. s'sAt the outer end of the hub 92 is-a-large -pu1ley. I-03, and trained around the -Iatter is: a control -cableizl04.

The cable I04 is attached tohthe pulley I03 and-s50 extends rearwardly. from the. top. part .thereof through the opening 21 and.upwardly-alongthe upper arm component I I. The cable I04 is preferably enclosed within-a spring-woundhousing (not shown) and is attached atritszupper end.to.;-, 55

the usual shoulder harness, whereby aipull can be applied to the .cable whenetheoharnessed shoulder is shrugged downwardly-and forwardly. Automatic supinationv of the wrist member I 5 responsive to. forearm flexion iswobtained-bymo means of a force-transmittingesystem which will now be described. "Pivotedcat I05 on opposite sides of the elbow housing .-.2.0.-:are-two side bars I06 which are connectedat their. front ends by a crossbar I01 to forma yoke I I0-.- The crossban m g I0'I extends throughand is slidable withina hole I II (see Figures 7 and 7.8).. formed in the outer end of a lever arm-I I2. -The leverarmJ I2 is journalled intermediate. its-ends on the tubular support 93 and isslidable axially thereon; The-=b0t- 7 -is..disposede: generallymarallel months forearmmd- .=on.by means of set screws. 1213.:1- j 1' at, mSlida-bly: mounted: on the tubular support? alongside the lever arm :II2 iscadownwardly exroller.

-centerline; and is SllPDOl'llEdi-fIiOIIlwUBiOWIbY azb'all bearing roller I I6, which is mounted on a pim:t

. securedin alinedholes in;the.-ends;of two bracket iiarms .:I2 I.t.-and I22. ;:.The bracket zarms -I2I,.;I22 are mounted. on and depend. from 'thertubular support 93,.and are locked against turning there.-

tending stationary gear sector. :I.2 4'- -.having. .teeth 125 of the same pitch and pitch diameter'as'the teethz-l I4. The gear sector I24.is adapted toxabe shifted axially along the. tubular; supportzz93,

carrying the lever arm I .I2 and rotatablegearsector-H3 with it, and to this end a rod .-I2 6-is:slidably. disposed within the tubular. supportmem- .ber. The ends of the rod I 26 project a'short dis- :tance-beyond the'ends of the tubular member. 93 and have buttons I30 provided thereon, whereby fore need notebe describedrzin *furtherixdetail go' the amputee cancs'hift the rod' in one; direction or the other by pressing on one of the buttons.

The stationary sector I 24. is connected to :the'rod IZB-bymeans of a screw I3I whichisthreaded into both of the members I24 and I26, and extends through axially elongated slots I32 in opposite sides of the-tubular support member 93.

The lever arm' I I2 is confined on the opposite side by a ring I33 which'lis: slidably mounted on .the tubular support [93. \The ring I33 :.is connected to the rod .I26 by means of" a;.screw-I34 which is threaded into both of the members I33 and I26, and extends through axially elongated slots 13%: in opposite sidesof. the tubular support member 93. Thus;= .whenthe rodrflIZG iis shifted axially within the support member 93,the

'ring a I33 -and stationary gear sector- 124: are moved with it, and since the lever arm. II2-is confined between these members, the lever arm is also shifted axially withthe rod-- I26. Detent means are provided for holding the rod I26 in -either of itstwo positions; said-detentmeansbeadapted to-seat ineither of two notches l40'or I M (see Figures 7 and: 8) in-the 1 inside surface of the tubular member 93. l

J The rack II5-is clamped between two sidebars 142 which extend down over the sides ofthe roller IIB, thereby centering the rack-on the Downwardly extending projections I43 and I44 at the front and rear ends ofthe rack II5 are'engageable with theroller IIG to limit the fore and aft travel of the rack. v i v The side bars I42 extend forwardly and'upwardly from the rack I I5 and aresecured at their front ends to opposite sides of another rack I45. The teeth of the rack I45 are disposed along one side thereof, and mesh with a pinion I4Bthat is journalled on the-pin 42. The rack I45 is confined on the other side by a ball bearing roller 1% which is mounted on a pin I5I extending down into a hole in the boss 45 of tongue 33.

Fixedly mounted ontop of the pinion I46 isa bevel gear I52, the teethof'which mesh with another bevel gear I53-formed integrally with the tubular portion I5 at the rear end thereof. Thus, the wrist member I5 is rotated about the prone.- tion-supination axis by bevel gears I52 and I53; the former being. coaxial with the flexion-extension axis, and the/latter. beingcoaxialwith the pronation-supination; axis. .Since the axesciof .the gears rzcoincidei withcrthe; axes of .rmoyement .or the. .wrist;member...J 5.2.:2the :meslri. ofzthe'z'gears unaffected by the. position. of the wrist memher.

In. order to maintain the path of the control wire 90 at a substantially constant length for-all angular positions of the wrist member I about either of its axes, the control wire is confined between two laterally spaced rol1ers.i54 which .areiarranged on opposite sides of the pronationsupination axis and slightly to the. rear of-the "fiexion-extension axis. The rollers I54 are spaced .apart just slightly. more than the diameter of the wire 90, as shown in Figure 5, and thezplane of their axes is preferably located about .078 to the rear ofthe flexion-extension axis. Thisarrangement has been found to give a substantially constant length to the path of the control wire forall angular positions of the wrist housing 34 aboutthe flexion-extension axis, and since the path of the control wirev also lies. directly on 'the pronation-supination .axis, the length of the :path of the control wire is unaffected by rotation of the wrist. member I5on its ball bearings releasing the lock, which is done by pressing, downwardly on'the free outer end of the locking lever 46 to unseat the pin 53 from its hole 55. The wrist housing 34 is then swung around to the desired position of fiexion, and the looking lever 46 is released, allowing the pin 53 to seat in another hole 55. If the arm is to be used with wrist supination coupled to forearm flexion, the left hand button I30 on the rod I26 is pressed inwardly, shifting the rod to the-right. Lever arm H2 is carried to the right with the rod I26, engaging the sector II 3 with the rack H5, and at the same time, the stationary gear sector I24 is moved out of engagement with the rack H5. In this position, flexion of the forearm with respect to the upper arm causes the yoke IiIl to move forwardly relative to the forearm component I2, rocking the lever arm H2 and gear sector H3 in a counterclockwise direction. This rotational movement of the gear sector I I 3 causes the rack H5 to be moved rearwardly,carrying the rack I45 with it and thereby rotating the pinion I46, and bevel gears I52, I53, which drives the wrist member I 5 about its pronation-supination axis.

If it is desired touncouple the wrist unit I4 from the upper arm component, the, right hand button I 30 on the rod I25 is pressed inwardly, shifting the movable gear sector H3 out of mesh with the rack H5, and carrying the stationary gear sector I24 into engagement therewith. With the rack I thus meshed with the stationary gear sector I24, the wrist member I5 is locked against rotation, and remains in a fixed position with respect tothe forearm component I2. One of the advantages of the invention is that the angular position of the hook unit I6 about the pronation-supination axis can readily be adjusted by merely flexing the forearm while the gear sector H3 is meshed with the rack H5, un-

rod: L I26 is athen shifted to the left, locking the wrist member"35in the adjusted position.

While we: haveshown and described in considerableodetail' what webelieveto bethe preierrediorm of our. invention, it is'to'be understood .that: such details are notrestrictive,- and that various changes may be-made in the shape and arrangement ofthe'. several parts without departing from the scope of theinvention, as defined in the appended claims.

.-We claim i -1. In an-artificial arm having an-upper arm component. and a forearm component swingably connected thereto by an-elbow joint, awrist unit comprisingawmember pivoted on the outer end of said-forearmcomponent for swinging movement aboutrthe wrist fiexion-extension axis;

another memberjournaled on said first named member for rotation about the pronationsupinationaxis, said last-named member being spaced outwardly from and swingable about said 'fiexion-extension axis, and drivingmeans connected to said upper arm component and having a portion thereof coaxial with said flexionextension axis for rotating said last-named member about said pronation-supination axis responsive to flexion and extension of .saida-forearm component with respect to said .upper arm component. 1 i

' 2. :In an artificial arm having a'forearm component, a wrist unit comprising a member pivoted on said forearm fcomponent"v for angular movement about the fiexion-extension axis, another member journaled. on said fir'st-named member a for rotation .a-boutrthe pronation-supination axis,

said pronation supination axis 'beingswingable a with said first-named member about said flexionextension. axis, said-last-named member having a portion extending rearwardly through said 15 first-named member coaxial. with said pronationsupination axis, and rotatable udriving uneans 'zcoaxial with :said fiexioneextension axis and engageable :with said rearwardly extending portiontoerotate'said last-named member about said pronation-supination axis. I

53. In .an artificialarm'having a'forearm component, a wrist unit comprising a'member pivoted extension -axis,- said :last-named member having a tubular portion extending rearwardly through .said -first-n'amed. member .coaxial with said ,pronation-supinationaaxis, a bevel gear fixedly mounted on saidxtuhular portion, and another bevel gear journaled on said forearm component coaxial with saidwflexion-extension :axis and :meshing with said first-named bevel gear to rotate said last narne'd member about said pronationesupination axis.

L'In an artificial .arm having a forearm component, a wrist unit comprising a member pivoted =on said "forearm component for angular movement abou'ttheflexion-extension axis, another member journale'd onsaid first-named member for rotation about a .pronation-supination axis intersecting said flexion-extension axis, the distal end 'of said-*last-namedzmember being adapted 'to receive a hand or hook having operatingmechanism provided therein,- said last-named member having a tubular portion-extending reartillthehook unit is :at. the desiredangle. The '(Q-AivartiIy through saidsfirst-named'member coaxial with said pronation supination' axis, a 'flexible control cable extending" through the center of said tubular member and having means at the outer end thereof adapted for connection with said operating 'mechanism, a pair of laterally spaced rollers disposed on opposite sides of said cable closely adjacent said fiexio'n-extension axis, said rollers confining the-path of saidcable to the intersection of said axes, whereby the length of said cable path remains constant for all angular positions of said last-named member, and rotatable driving means coaxial with said flexion-extension axis and engageablefwith, said tubular portion to rotatesaid last-named'memher about said-pronation-supination axis. j

5. In an artificial arm' having an upperarm component and a forearm component swingably connected thereto by an elbow joint, a wrist unit comprising a member mounted on said forearm component for angular adjustment about the wrist fiexion-extension axis, another member journaled on said first-named member for rotation about the pronation-supination axis, said pronation-supination axis being swingable with said first-named member about said fiexionextension axis, driving means connected to said upper arm component and to said last-named member for rotating the latter about said pronation-supination axis responsive to flexion and extension of said forearm component, and means for disconnecting said driving means and locking said last-named member against rotation, whereby said last-named member can be locked in any angular position about said pronationsupination axis.

6. In an artificial arm having an upper arm component and a forearm component swingably connected thereto by an elbow joint, a wrist unit comprising member mounted on said forearm component for angular adjustment about the wrist fiexion-extension axis, another member journaled on said first-named member for rotation about the pronation-supination axis, said pronation-supination axis being swingable with said first-named member about said fiexionextension axis, a gear sector pivoted on said forearm component and slidable axially thereon, a link connecting said sector to said upper arm component, whereby said sector is rocked when said forearm component is flexed and extended, a rack adapted to be meshed with said sector and to be moved longitudinally thereby, said rack being connected with said last-named wrist member to rotate the latter about said pronationsupination axis, a non-rotatable gear sector disposed coaxial with said first-named sector and slidable axially therewith to engage said rack and hold the same against longitudinal movement, and means for sliding said two gear sectors axially so as to disengage one of them from said rack and engage the other one therewith, whereby said last-named wrist member may be operatively connected to said upper arm component for supination coupled to forearm. flexion, or disconnected therefrom and locked against rotation.

7. In an artificial arm having a forearm component and an upper arm component swingably connected thereto by an elbow joint, a wrist unit comprising a member pivoted on said forearm component for angular movement about the wrist flexion-extension axis, another member journaled on said first-named member for rotation about a pronation-supination axis intersecting said fiexion-extension axis, the distal end 10 j of said last-name'd'm'emberj being adapted tore- 'ceive a hand or hook having" operating mcha nism provided-therein, said "last named member having tubular portion extending rearwardly through said first-named member coaxial with said pronatio'ri supination axis, flexible control cable extent ling' through the center of saidtubu lar'fmember and having means at the outer end thereof adaptedfor' connectionwith said operating mechanism, a pair of laterally spaced rollers disposed on opposite side's'of said cable' closely adjacent said=fiexion extension axis, said rollers confining 'thepathof said cable to the intersection of said axes, whereby thelength'of said cable "path remains constant" for all angular positions of said last named member, a bevel gear fixedly in'ou'ntedbn the rear end of said tubular portion, another bevel gear journaled on said forearm component coaxial with said flexion-extension axis and meshing with said first-named bevel gear to rotate said last-named member about said pronation-supination axis, and means connected to said upper arm component for rotating said last-named bevel gear responsive to flexion and extension of said forearm component.

8. In an artificial arm having a forearm component and an upper arm component swingably connected thereto by an elbow joint, a wrist unit comprising a member pivoted on said forearm component for angular movement about the wrist flexion-extension axis, another member journaled on said first-named member for rotation about a pronation-supination axis intersecting said flexion-extension axis, the distal end of said last-named member being adapted to receive a, hand or hook, said last-named member having a portion extending rearwardly through said first-named member coaxial with said pronation-supination axis, a bevel gear fixedly mounted on said rearwardly extending portion, another bevel gear journaled on said forearm component coaxial with said flexion-extension axis and meshing with said first-named bevel gear, a'pinion fixed to said last-named bevel gear, a rack meshed with said pinion, means connecting said rack with said upper arm component, whereby flexion and extension of said forearm component causes said rack to be moved longitudinally, thereby rotating said bevel gears and causing said last-named wrist member to rotate about said pronation-supination axis, and

means for disconnecting said rack from saidupper arm component and locking the same against longitudinal movement, whereby said last-named member can be locked in any ngular position about said pronation-supination axis.

9. In an artificial arm having a forearm component and an upper arm component swingably connected thereto by an elbow joint, a wrist unit comprising a member pivoted on said forearm component for angular movement about the wrist flexion-extension axis, another member journaled on said first-named member for rotation about a pronation-supination axis intersec ing said flexion-extension axis, the distal end of said last-named member being adapted to receive a hand or hook, said last-named member having a portion extending rearwardly through said first-named member coaxial with said pronationsupination axis, a bevel gear fixedly mounted on said rearwardly extending portion, another bevel gear journaled on said forearm component coaxial with said flexion-extension axis and meshing with said first-named bevel gear, a pinion fixed to i said lastena b v s as, 3-1 39 meshed with said pinion, a gear sector pivoted on said component and. slidable axially into and out of mesh with saidLrack, a link connecting said sector to said upper arm component, whereby said sector is rocked when vvsaid forearm component is flexed and extended a non-rotatable gear sector disposed coaxial with said firstnamed sector and: slidable axially therewith to engage said rack and hold the same against longitudinal movement; and neans for simultaneously sliding said two gear-seotorsiaxially so as to disengage one of them from .saidrack and engage the other one therewith, whereby said last-named wrist member maybe operatively connected to said upper arm component for supination coupled to forearm flexion, or. disconnected therefrom REFERENCES men The following references are ofrecord in the flle o! this'patentr I a UNITED STAT S PATENTS Number Name Date ,7

999,484 Carries I --I Aug. 1, 1911 1,046,966 Carnes III I -Dec. 10, 1912 1,507,682 Pecorella etal, Sept. 9, 1924 2,287,781

Carne s II .June 30, 1942

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