US2560286A - Knee lock for artificial limbs - Google Patents

Description

July 10, 1951 J. E. HANGERJJI KNEE LOCK FOR ARTIFICIAL LIMBS 4 Sheets-Sheet 1 Filed May 19, 1948 o INVENTOR. JamiesElHangezgH 7 qwmuf July 10, 1951 J. E. HANGER,I]I

KNEE LOCK FOR ARTIFICIAL LIMBS 4 Shets-Sheet 2 Filed May 19, 1948 I E! Z.

INVENTOR. EHan 381, H

Jalnes BY July 10, 1951 -J. E. HANGERJE KNEE LOOK FOR ARTIFICIAL LIMBS 4 Sheets-Sheet 5 Filed May 19, 1948 INVENTOR.

Jamesl'l'flanyenm BY y 10, 1951 J. E. HANGER, 111: 2,560,286

KNEE LOCK FOR ARTIFICIAL LIMBS F iled May 19. 1948 4 Sheets-Sheet 4 IN V EN TOR.

Patented July l0, 195i UNITED S TAT ES PATENT O F Fl "2,560,286

KNEE LOOK FOR ARTIFICIAL LIMBS James E. Hanger, ,II-I, Washington, .D. 13., assignor to Metal Limb Manufacturerall-nc Washington, D. (3., a corporation of Delaware Application .May 19, 1948, Serial No. 27,87 6

15 Claims.

The present invention relates to a new and improved knee lock for artificial limbs.

An important feature of the invention consists in associating with the knee joint of an artificial limb, a releasable locking mechanism including means for maintaining the thigh member and the calf member of an artificial limb in a vertical or straight position when the wearer is taking a forward step, and providing means operable by the application of pressure on the ball or too of the foot to release the locking mechanism. In order to re-engage the locking connection of :the thigh member with the calf member, when the thigh member and calf member are in vertical or aligned position, it is necessary for the wearer to apply weight on the heel of the foot which causes the locking mechanism to be moved to its latched position, andthus prevent bending :of the thigh member and the calf member at the knee joint or buckling of the knee as the wearer ;pro ceeds to take a forward step. As the body of the wearer approaches a vertical position above the artificial leg, his weightshifts over the 'knee center andit is no longer necessary for the artificial leg to require the knee lock to prevent it from buckling at the knee joint. Therefore, as the body of the wearer moves forward, .depression of the toe or ball of the foot causesthe knee lock to unlatch allowingthe wearerto bend the knee so as to begin the next forward step,

thus providing simple,eificient and positive means for fiexingthe knee joint, and for preventing the collapse-of the limb when the weight of the-wearer is placed on the knee joint in the act of walking.

A further object consists in associating with the knee lock mechanism, a lost motion connection which is operable when the locking 'pawl'is moved out of engagement with a latch on vthe thigh member and the foot member is returned to its normal position, to prevent engagement-of the pawl with the latch upon the return ;-movement of the foot member. Additionally, yieldable means-are provided when the pawl is moved into locking engagement with the latch forallowingreturnof the foot member to its normal horizontal position without disturbing the locking .connection'of the pawl with thelatch member-so that the thigh member .and the calf member will be maintained in vertical alignment until the toe .of-the .foot is again depressed.

Another object consists in providing a knee lock mechanism which .is connected to .the .calf member and includes a pawl arranged to be moved ,intoand out of engagement with .pawl

2 receiving means on the thigh member. h'control bracket is fixed to the lock mechanism and has means rotatably connected thereto which areoperatively connected to the pawl, and also to an operating rod which is connected to the ,foot member, so that upon rocking' of the foot member relative to the calf member fromits normal position and in one direction when the thigh member and calf member are in aligmnent, for actuating the rotatable means to move .the pawl into locking engagement with the latch means,

andupon :rocking the foot1-memberfrQm -its ;nor- 7 mal position and in an opposite direction, :for actuating the rotatable means to ,mov e -.the ;paw1 out ofengagement with the latch ,mea-ns.

O.t-her objects and advantages of the invention vwill become apparent from the following description-when taken in conjunction with the accompanying claims and-drawings. t

Referring to the drawings in which are disiclosed several preferred embodiments of ,the in- .;vention:

Figure l is a vertical sectional view of anartificial limb constructed in accordancewith-the present invention, showing the --th-igh portion locked to the -calf portion and the parts in-the .EDQsi-tion they assume when the wearer -takes a :forward step.

.Figurezis anenlarged detailedrearview of the knee jointshown inFigure ,1.

. Figure .3 a sectional view taken substantially alongthe dine .3.,3.zof, Figure l Figure 4 is an enlarged verticaksectional view takenlsubstantially alongthe line.44.of;Eigure;2.

Figure :5 :is an enlarged detailed :sectionalwievv staken substantially along the line 5-5 .of Figure 4.

.Figure 6 :is anxenlarged detailedsectional xview 'takensubstantially along the linens-6 .Of'ZEIig ure 14.

Figure .7 is a sectional view. taken substantially along-the line 1-? of Figure '6.

Figure 8 is -a detailed side view showing'the position -of the friction lever, transfer pin, and operating rod when'the parts are-in locking position.

-Figure 9 is 'a view similar to Figure f3 showing the parts when the locking. mechanismis moved to its released position.

Figure 10 is an enlarged "sectional plan wi'ew taken substantially along the '1ine. |"ll ll]. of I'Fig- 111191. m ,Figure l1 is a sectional viewtaken-subfillg ptially along the line fill-1H ,o'f .Eigure .110.

Figure 12 is a perspective view of the transfer lever.

Figure 13 is a perspective view of the friction lever.

Figure 14. is a perspective view of the control bracket.

Figure 15 shows the position of the artificial limb as the leg is moved forward, and shows the locking pawl in full lines just prior to the operating rod taking up the lost motion and moving the locking pawl into engagement with the bot tom of the thigh member.

Figure 16 shows the position of the artificial limb and the locking mechanism when the body of the wearer is moved over the artificial limb with the parts in locked engagement, and also shows in dotted lines the release of the locking mechanism after the application of pressure on the ball of the foot and when the knee is bent to begin the next forward step.

Figure 17 is a vertical rear section-of a modified form of artificial leg constructed in accordance with the present invention.

Figure 17a is an enlarged vertical sectional view taken substantially along the line lla-l'|a of Figure 19;

Figure 18 is a rear view of the knee joint structure shown in Figure 17.

' Figure 19 is a sectional View taken substantiall y at right angles to that shown in Figure 17, and

Figure 20 is an enlarged sectional view taken substantially along the line 2ll20 of Figure 19.

' Referring to the drawings, the artificial limb constructed in accordance with the present invention includes a hollow thigh member or section 21, a hollow calf member 22, and a foot member' 23,'which maybe made of any suitable light, durable composition or metal. The bottom of the thigh member is curved as at 24 and shaped to fit; within the upper hollow portion of the calf member '22 in order to provide a movable knee joint and permit free movement of the knee joint without danger of a garment of the wearer becoming caught between the joint. Extending upwardly from opposite sides of the calf portion 22 adjacent the top thereof, are a pair of fixed bearing lugs 25 (Fig. 2) having transverse aligned openings through which extends a fixed knee bolt 21 provided with enlarged head portions 28 at its opposite ends that bearagainst the lugs 25. The thigh member 2| adjacent the knee joint 24 is rotatably mounted on the knee bolt 27 and the bottorn or the knee joint 24 is provided with a notch or recess 29. A metal guard plate lB having an opening [Si-registering with the recess 23, may be secured by the screws 20 to the bottom of the knee joint 24, (Fig. 3).

- The locking mechanism associated with the artificial limb, may include a metal member or bar 33 having at its upper end a lateral projecting'portion 3| (Fig. 4) provided with a transverse opening 32 through which loosely extends the knee bolt 21. The bar is preferably formed with a depending channel-shaped portion or member 33 which extends downwardly through a central slot 34 in the rear of the thigh member 2 l', and has spaced parallel sides 35 (Fig. 3). The depending portion 33 is firmly secured to the rear wall of the calf section in any suitable manner such as by the retaining screws 36. A flat spacer Spring 31 may be connected at its lower end as at 38 (Fig. 4) to the portion 33 and has its upper portion extending over and engaging the underside of a transverse pin 39 as at 40. A locking pawl or lever 4| is pivoted at one end as at 42 to the aseofas 4 spaced sides 35 of the channel portion 33 of the member 33, and is provided at its opposite end with a nose 43 which is arranged to be moved into the recess or detent 23 when the thigh member 2| and the calf member 22 are in alignment, so as to lock these members together and prevent buckling of the artificial limb at the knee joint. The end of the pawl 4| may be faced with a leather covering or the like 4| to prevent scraping of the pawl on the knee in te event the lock does not entirely disengage. The forward wall of the slot 34 may be provided with a rubber buffer 44 that bears against the bar 33 when the latter is in its vertical position. A control bracket or member 45 is provided at one end with a bent flange portion 46 (Fig. 14) which extends into the channel member 33 (Fig. 3) and may be secured thereto by the retaining bolt 33 and the spaced screws 4?. The opposite end of the control bracket 45 terminates in an enlarged circular head 48 having a central opening 49. A friction lever 50 is provided at one end with an enlarged circular portion 5! having an opening 52 (Fig. 13) which registers with the opening 49 in the control bracket 45. The lever 50 has intermediate its ends, an enlarged opening 53 and ter- Inmates at one end thereof in a laterally extending flange 33 formed with a vertical through opening 55 through which loosely extends a slidable connecting rod 56 having a head 5'! at its lower end and positioned below the flange 54. The upper end of the rod 56 extends into an opening 58 in a boss or member 59 so as to be rigidly secured thereto such as by welding or the like. The upper end of the boss 59 is bifurcated so as to form the spaced arms 69 which overlap the pawl 4! and are pivotally connected thereto by the pin 6i (Fig. 5). Surrounding the rod 56 and confined between the flange 54 and the boss 59 is a coil expansion spring 62 which provides a lost motion connection between the friction lever 50 and the pawl 4| in a manner and for the purpose that will subsequently be described. A transfer lever or member 63 is positioned adjacent the control bracket 45 opposite to the friction lever, and has at one end an opening 64 which registers with the opening 49 in the control bracket, and has extending laterally and outwardly therefrom a transfer pin or stud 65 which extends into the opening 53 in the friction lever and is of much smaller diameter than the opening 53 so as to be loosely mounted therein for the purpose of permitting lost motion or movement of the transfer lever a limited or predetermined distance before operating the friction lever. The pin 65 may carry, a flexible rubber sleeve 65' also of smaller diameter than the opening 53 and arranged to engage the wall thereof upon vertical movement of the rod 18. The transfer lever 63 is also formed with an opening 66 through which rotatably extends a screw 61 that is threaded as at 68 to a sleeve 63 to permit independent movement of the transfer lever relative to the sleeve 69. A spring metal washer H3 is positioned adjacent the friction lever 50 and has a central opening which registers with the opening 52 on the control lever and may be spaced therefrom by a friction fiber washer H. A shoulder washer 12 having a threaded central bore 13 (Fig. 5) registers with the openings in the control bracket 45, friction lever 50, transfer lever 63, and spring washer Hiv so as to receive a threaded bolt 14 in order to firmly clamp these parts in position. The shoulder washer 12 preferably carries a metal washer 15 which bears against the transfer lever escapee 6'3. Interposed between the transfer lever and the bracket 45 may be a friction fiber washer I6. A threaded locking nut I1 is connected to the threaded bolt I4 so as to bear against the shoulder washer I2 in order to releasably maintain these parts in a fixed position. An operating rod I8 has its upper end portion i9 extending through the sleeve 59 and a tubular bearing member 80 (Fig. 6) which is internally threaded as at ill to receive the external threads on a reduced split portion 82 of the sleeve 69. The upper end of the portion 82 may be provided with flared arms 83 through which extends the outer end of the portion I9 of the rod I8. It will be seen that screw 61 extending into the sleeve 69 bears against the portion I9 of the rod so as to provide means for maintaining the rod 78 in any desired adjusted position.

The foot member 23 is preferably formed with a hinged toe section 84 that is connected to the foot section by a rubber insert 95. The foot member also has an intermediate raised ankle portion 86 and recesses 81 and 99 on opposite sides of the raised portion 95. The lower end or bottom 94 of the calf member 22 is provided with a depending curved lip portion or member 89 (Fig. 1) which bears against a rubber insert 90 in front of and adjacent to the raised portion 85. Within the heel recess 88 is a resilient rubber plug 9I which at its lower end bears against a rubber strip 92 and is of sufficient length as to extend upwardly into a recess es formed in the bottom wall 94 of the calf member 22. The rubber inserts 90 and SI on opposite sides of the pin 95 provide yieldable means for normally maintaining the foot member 23 in substantially a horizontal position, when downward pressure is removed from the toe and heel sections of the foot. A fixed transverse ankle pin 95 is embedded in the bottom 94 of the calf member 22, and the foot member 23 is rotatably connected to the calf member 22 by a looped or inverted U-shaped bolt 96 that extends over the pin 95 and has depending threaded arms 9! projecting through openings 98 in the raised portion 85. The lower ends of the arms 91 extend into a recess 99 so as to be connected to the clamping bolts I09. A friction plate IOI within the recess 99 may be positioned so as to be engaged by the bolts I00 when the U-bolt 96 is secured in position. The U-bolt 96 has extending outwardly therefrom an arm I02 (Fig. 10) which is pivotally connected to a clevis I03 by the pin I00 (Fig. 11). The lower end of the rod I8 extends into an opening I05 in the top of the clevis I03 so as to be secured thereto.

The foot member 23 is movably connected to the lower end of the calf member 22 by the U-shaped bolt 95 through its pivotal connection with the pin 95, so that the foot may be rocked about its pivot in such a manner that the rubber insert 90 will allow a certain forward displacement of the foot member while the rubber plug 9|, which is more resilient than the plug insert 90, will allow a greater rearward displacement of the foot member. A yieldable strip of rubber or the like I06 may be positioned below the rubber insert 85 at the ball of the foot and overlaps both the foot member 23 and the toe section 84. The bottom of the foot from the instep over and above the toe 9 may be covered with a strip of leather or the like I01, and a flexible strap or piece I09 may be positioned in the space between 6 rubberportion 92 of the heel may similarly be covered with a leather piece I09 that is suitably secured to the rear portion of the foot member 23. In operation of the artificial limb, assuming that the thigh member 2| and the calf member 22 are in vertical alignment and the latch mecham's'm is released and about to be moved to its locked position to prevent collapse of the knee joint and the user moves his artificial leg forward to take a step (Fig. 15), the knee of the wearer will 'be in a straight position and as the weight of the body is placed against the heel 92, the rubber plug 9| is depressed within the recess 88 causing the U-shaped bolt 95 to rock on the pin 95 and the arm I02 to be moved upwardly, thus raising the rod I8, which in turn causes the transfer lever 63 and the friction lever 59 together with the metal and fiber washers, and the pin I0 to be rotated relative to the fixed control bracket 45. A the friction lever is operatively connected by the rod 56 to the pawl l I, this upward movement raises the pawl so that the nose 43 is moved and maintained within the opening or catch 29 in the bottom of the knee portion 94 (Fig. 4-). In other words, the pawl AI is moved from its disengaged position as shown in full lines to its locked position as shown in dotted lines in Figure 15. The transfer pin 65'i also moved upwardly in its slot 53 (Fig. 8) so as to bear against the upper wall thereof in order to cause simultaneous movement of the friction lever 59 and the transfer lever 93 when "the rod I8 is raised beyond a predetermined limit. It will be seen that during this forward movement of the artificial leg, that the locking mechanism maintains the thigh member 2| in a straight fixed position relative to the calf member 22 so as to prevent buckling of the artificial limb and that it is impossible to bend the leg-or for the members to buckle at the knee as the wearer takes a forward step and walks on the top of the shoe member 23 and the toe '84 so as to underlie the leather covering I01. The

his artificial leg. As the wearer approaches a vertical position above the artificial leg (Fig. 16), his weight shifts over the knee center and it is no longer necessary for the leg to have a knee lock to prevent it from buckling. It mi ht be mentioned that the instep rubber functions to stop the ankle movement of the foot member 23 as the wearers body moves forward so that when he depresses the toe portion 89, the artificial limb assumes the position as shown in dotted lines in Figure 16, with the result that as the pressure is applied to the ball of the foot, the yieldable rubber inserts 85 and 9e are compressed and the foot member 23 moved to an inclined position so as to cause the. U-shaped bolt 96 to rock on the pin and move the arm I02 downwardly. This movement of the rod I02 lowers the operating rod l8 thus causing the locking mechanism to move the pawl lI out of engagement with the recess 93 so that the knee joint may be flexed. As the compressed rubber inserts 35 and 99 return to their normal positions, the pawl 4! is prevented from being moved into locking engagement with the recess 93 by the lost "motion connection between the transfer'pin 65 in the opening 53 of the friction lever 50 which allow a predetermined upward movement of the rod I9 without disturbing the disengaged position of the pawl 4|. In order to reengage the pawl it is, of course, necessary to put the weight on the heel 92 of the foot (Fig. 15) which causes the heel rubber 9I to be depressed. Durin this upward movement of the rod I8 the lost motion between the'transfer pin 55 and the friction lever 50 is' taken up by pin 35 engaging the upper wall of the opening 53 (Fig. 8). When the heel rubber 9| and the foot member 23 return to their normal position (Fig. 16), it will not cause disengagement of the pawl 44, which remains locked until the toe 84 of the foot is again depressed. This is due to the fact that when the pawl AI is moved to its locked position and the foot member returns to its normal horizontal position, displacement of the pawl is prevented by the compression of the spring 62, which functions to take up the excess amount ofmovement of the friction lever 50 by the engagement of the lug 54 with the lower end of the spring 62 so as to compress the latter as the lug 54 i moved upwardly and away from the head 51 of the connectin rod 56 (Fig. 8), without disturbing or causing any vertical movement to be imparted to the connecting rod 56 and the pawl 4!, so that the pawl will remain locked until the toe of the foot is again displaced. In other words, the spring 62 constitutes a lost motion means which functions to take up the excess amount of movement of the friction lever 5| caused by the considerable displacement of the rubber heel member 9| when the latter is compressed. The adjustment of the shoulder friction washer E2 on the bolt I4 is just tight enough to overcome the pressure of the spring 62 on the connecting rod 55 so that the latter remains set against the pressure of spring 62 until it is moved by the transfer pin. Thus, it will be seen that the locking mechanism allows the knee to remain free to swin when it is unlatched and until the weight of the wearer is applied to the heel of the foot. Consequently, the wearer may convenientlyv bend the artificial limb at the knee to sit down or get up without causing the parts to be moved into locking engagement, and the knee will remain unlocked until the foot is straightened out and pressure applied to the heel (Fig.

In the modified form of the invention shown in Figures 17 to 21 inclusive, the thigh member III] is pivotally connected as at I I l to the calf section H2 by a transverse pin H3. The bottom H4 of the thigh section i is which forms the knee joint is provided with a centrally disposed curved slot IE5 that extends above the transverse pin H3. Within the slot H5 is a horizontal bar H3 which terminates at one end in a tubular portion or bearing sleeve H'I (Fig. 19) which preferably is locked to the transverse pin H3 by a set screw I I8. Extending downwardly and from the opposite end of the bar H6 so as to be movable as a. unit therewith, is a depending arm I I9, which is clamped or otherwise secured at its lower end as at I28 to a transverse bracket or strap I21 that is connected to the inner forward wall of the calf member H2 by the bolts I22. The lower intermediate portion of a flexible strap I23 passes under a roller I2l carried by the bar HE and is suitably connected at its upper ends to the waist belt of the artificial leg.

The bottom or knee joint portion H4 of the thigh member I I8 adjacent one of the side walls of the slot H5 such as the side I25, is provided with a recess or looking catch I26 that may be protected by a metal. plate I2!- having an opening registering with the recess I25. A locking mechanism substantially similar to the knee lock previously described, is connected to the rear inner wall of the calf, member H2 and preferably in cludes a vertical bar or member I28 having lateral projecting side arms I29 which are curved to conform with the curvature of the inner rear wall of the calf member H2 so as tobe secured thereto by the bolts Hill. The bar I28 above the arms I29 may be formed with spaced lugs I3I to which is pivotally connected as at I32 a locking pawl or latch E33. lhe bar I28 is positioned centrally and substantially in alignment with the slot H5 and in order that the pawl I33 may be moved into and out of locking engagement with the recess I25 in the side wall I25 of the bottom H4, the latch I33 is bent or ofiset as at I34 (Fig. 20) and has a forwardly extending free portion I35 provided with an arm I36 that engages the recess I26 when the thigh member IIB is moved into alignment with the calf member I I2 and the pawl I33 is raised to its locked position. A control bracket I3? is connected as at 538 to the bar I28 and has associated with it a friction lever I39, a transfer lever I49, a spring washer IGI, a metal washer hi2, and fiber washers U32 which are clamped together by a threaded bolt I43 and nut I42 so as to be rotatable upon the actuation of the operating rod 54%. The rod M4 is pivotally connected as at I i-5 to the transfer lever MB. The coil spring Hi5 carried by the connecting rod I4! provides a lost motion connection when the pawl I33 is in locked. engagement with the recess I26 and allows the foot member to be returned to its normal position after the heel has been moved to lock the pawl, without disturbing the pawl. The friction lever iBQ has an enlarged opening I39 for receiving a transfer pin M9 on the lever I49 for providing a lost motion connection similar in operation to the pin {55 (Fig. 3) The lower end of the operating rod Hi l is connected to an inverted U-shaped bolt carried by the foot member and similar in construction and operation to the foot 23 and its associated parts previously described. It will be noted that in this form of the invention the knee lock is not connected to the pin H3, and pawl H33 is offset so as to be moved into and out of locking engagement with its complementary oilset recess IZE, as contrasted to the centrally disposed latchd l and its associated parts previously described. Otherwise the construction and operation of both forms of locking mechanisms are the same. In both forms of the invention in order to release the locking mechanism, it is necessary to put the weight on the ball of the foot. To move the latch into locking engagement with its recess when the knee is in a straight position, it is required to put the weight of the user on the heel of the foot.

It will be seen that by reason of the novel locking mechanism as shown in the several figures of the drawing, that simple, eiiicie t, economical and positive means are provided for preventing blockling of the knee joint when the artificial limb is moved forward when taking a step, and that the knee lock can only be released upon the application of pressure to the ball of the foot. Moreover, this locking mechanism allows the knee to remain free to swing when it is unlatched until the thigh member and calf member are moved in alignment and Weight is applied to the heel of the foot. The knee lock is compact and constitutes a unitary structure which may be included as a permanent part of an artificial limb or may be readily installed on a used artificial limb at a minimum expenditure of time and effort. Additionally, the parts of the locking mechanism are conveniently positioned so as to be accessible for the purpose. of inspection and repair.

The invention is capable of various modificathigh member provided with a catch, a calf member pivotally connected to said thigh member,

a foot member pivotally connected to said calf member, a knee lock mechanism connected to the calf member and including a pawl. arranged to be moved into and out of engagement with said catch, a control bracket connected to the" calf member, rotatable means connected to said control bracket, means operatively connecting said rotatable means to said pawl, an operating rod connected at its lower end to said foot member, means pivotally connecting the upper end of said rod to said rotatable means, a lostmotion connection between the movable means and the pawl for allowing vertical displacement of the operating rod a predetermined distance when they pawl is disengaged from the catch without disturbing the position of the pawl, and-yieldable meansbetween the movable means and the pawl for allowing vertical movement of the operating rod without disturbing the pawl when the latter is in looking engagement with the catch, the parts being constructed and arranged so that upon rocking movement of the foot member in one direction to cause the operating rod and the rotatable means to move the pawl into engagement with the catch and upon movement of the foot member in an opposite direction to actuate the operating rod and the rotatable means to disengage the pawl from the catch.

2. An artificial limb having in combination, a.

f thigh member provided with a catch at the lower end thereof, a calf member pivotally connected to said thigh member, a foot member pivotally connected to said calf member, knee lock mechanism connected to the calf member and includof engagement with said catch, a control bracket connected to the calf member, a friction lever on one. side of said control bracket, means operatively connecting the friction lever to said pawl, a transfer lever on the opposite side of said bracket, means rotatably comiecting said levers to said control bracket, an operating rod connected at its lower end to said foot member, and means pivotally connecting the upper end of the operating rod to said transfer lever, the partsbeing constructed and arranged so that upon rocking of the foot member in one direction for rotating the friction lever and the transfer lever to move the pawl into engagement with said catch when the thigh member is in alignment engagement with said catch, a control bracket connected to the calf member, a friction lever on one side of said control bracket, means operaing a pawl arranged to be moved into and out means pivotally connecting th upper end of the operating rod to said transfer lever,- andmeans providing a lost motion connection between said transfer lever and said friction lever, the parts being constructed and arranged so that upon rocking of the foot member in one direction for rotating the friction lever and the transfer lever to move the pawl into engagement with said catch when the thigh member is in alignment with the calf member, and when thefoot member is rocked in an opposite directionfor rotating the friction lever and the transfer lever for releasing engagement of the pawl with said catch.

4. An artificial limb having in combination, a thigh member provided with a catch at the lower end thereof, a calf member pivotally connected to said thigh member, a foot member pivotally connected to said calf member, knee lock mechanism connected to the calf member and including a pawl arranged to be moved into and out of engagement with said catch, a control bracket connected to the calf member, a friction lever on one side of said control bracket, means operatively connecting the friction lever to said pawl, a transfer lever on the opposite side of said bracket, means rotatably connecting said levers to said control bracket, an operating rod connected at its lower end to said foot member, means pivotally connecting the upper end of the operating rod to said transfer lever, and yieldable means for providing a lost motion connection between the frictionlever and said pawl. for allowing vertical movement of the operating'rod without disturbing the pawl whenv the latter is in locked engagement with the catch, the parts to said thigh member, a foot member pivotally connected to said calf member, knee lock mechanism connected to the calf member and including a pawl arranged to be moved into and out of engagement with said catch, a control bracket connected to the calf member, a friction lever on one side of said control bracket, means operatively connecting the frictionlever to said pawl, yieldable means providin a lost motion connection between the. friction lever and the pawl for allowing displacement of the friction lever without disturbing the position of the pawl, a transfer lever on the opposite side of said bracket, means. rotatably connecting said levers to said control bracket, an operating rod connected at its lower end to said footmember, means pivotally connecting the upper endof the .operatingrod to said transfer lever, and means providing a lost motion connection between said transfer lever and said friction lever, the parts tively connecting the friction lever to said pawl,

a transfer lever on the opposite side of said bracket, meansrotatably connecting said levers to said control bracket, an operating rod connected at its lower end to said foot member,

' rotating the'friction lever and the transfer lever 11' for releasing engagement of the pawl with said catch.

6. In an artificial limb, a thigh member having a locking catch in the bottom thereof, a calf member, pivot means extending transversely of the thigh member for connectin the upper end of the calf member thereto to provide a movable knee joint, a bar rotatably connected to said pivot means and extending downwardly into said calf member, means connecting said bar to said calf member, a foot member pivotally connected to the lower end of said calf member, a locking pawl pivotally connected to said bar and arranged to be moved into and out of locking engagement with said catch, a control bracket connected to said bar, an operating rod operatively connected at its lower end to said foot member, a friction lever operatively connected to said pawl, a transfer lever pivotally connected to said operating rod, means rotatably connecting said friction lever and said transfer lever to said control bracket, and means providing a lost motion connection between said transfer lever and said friction lever, the parts being constructed and arranged so that upon rocking of the foot member relative to the calf member in one direction, when the thigh member and calf member are in alignment, for moving the pawl into locking engagement with said catch and when said foot member is moved in an opposite direction relative to the calf member for releasing the engagement of the pawl with said catch.

'7. In an artificial limb, a thigh member having a locking catch in the bottom thereof, a calf member, pivot means extending transversely of the thigh member for connecting the upper end of the calf member thereto to provide a movable knee joint, a bar rotatably connected to said pivot means and extending downwardly into said calf member, means connecting said bar to said calf member, a foot member pivotally connected to the lower end of said calf member, a looking pawl pivotally connected to said bar and arranged to be moved into and out of locking engagement with said catch, a control bracket comiected to said bar, an operating rodoperatively connected at its lower end to said foot member, a friction lever operatively connected to said pawl, a transfer lever pivotally connected to said operating rod, means rotatably connecting said friction lever and said transfer lever to said control bracket, yieldable means between the friction lever and said pawl for allowing vertical displacement of the operating rod without disturbing the pawl when the latter is in locked engagement with the catch, and means providing a lost motion connection between said transfer lever and said friction lever, the parts ,being constructed and arranged so that upon rocking of the foot member relative to the calf member in one direction, when the thigh member and calf member arein alignment, for moving, the pawl into locking engagement with said catch and when said foot member is moved in an opposite direction relative, to the calf member for releasing the engagement of the pawl with said catch.

8. In an artificial limb, a thigh member having a locking catch in the bottom thereof, a calf member, pivot means extending transversely of the thigh member for connecting the upper end of the calf member thereto to provide a movable knee joint, a bar rotatably connected to said pivot means and extending downwardly into said calf member, means connecting said bar to said calf member, a foot member pivotally connected to the lower end of said calf member, a locking pawl pivotally connected to said bar and arranged to be moved into and out of locking engagement with said catch, a control bracket connected to said bar and having an inwardly extending arm provided with an opening, a friction lever on one side of said control bracket, a transfer lever on the opposite side of said bracket, a spring washer adjacent said friction lever, a friction washer adjacent said transfer lever, said levers and said washers having aligned transverse openings, a clamping bolt extending through, said openings for rotatably connecting said levers and said washers to said control bracket, an operating rod pivotally connectedat its upper end to said transfer lever, means operatively connecting said friction lever to said pawl, means providing a lost motion connection between said transverse lever and said friction lever, means providing a lost motion connection between said friction lever and said pawl, and means operatively connecting the lower end of said rod to said foot member, the parts being constructed and arranged so that upon rocking of the foot member relative to the calf member in one direction when the thigh member and calf member are in alignment for moving the pawl into locking engagement with said catch, and when said foot member-is moved in an opposite direction relative to the calf member for releasing the engagement of the pawl with said catch. 7

9. A knee lock for artificial limbs including a fixed bracket connected to a limb member, a support rotatably connected to said bracket, a friction lever carried by said support, a transfer lever carried by the support, a pawl pivotally connected to the lock, means operatively connecting the friction lever to said pawl, and an operating member connected to said transfer lever for operating the pawl upon rotation of said levers by the operating member.

10. A knee lock for artificial limbs including a fixed bracket connected to a limb member, a support rotatably connected to said bracket, a friction lever carried by said support, a transfer lever carried by the support, a pawl pivotally connected to the lock, means operatively connecting the friction lever to said pawl, an operating member connected to said transfer lever for operating the pawl upon rotation of said levers by the operating member, and means providing a lost motion connection between the transfer lever and the friction lever.

11. A knee lock for artificial limbs including a fixed bracket connected to a limb member, a support rotatably connected to said bracket, a friction lever carried by said support, a transfer lever carried by the support, a pawl pivotally connected to the lock above said bracket, means operatively connecting the friction lever to said pawl, an operating member connected to said transfer lever for moving the pawl upon rotation of said levers by the operating member, and means for providing a lost motion connection between the friction lever and said pawl.

12. A knee lock for artificial limbs including a fixed bracket connected to a limb member, a pin rotatably connected to said bracket, a friction lever carried by said pin on one side of said bracket, a transfer lever carried by said pin on the opposite side of said bracket, a locking pawl pivoted to said lock above said bracket, a rod connected to. said pawl and extending loosely through said friction lever, a coil spring surrounding said rod and confined between said friction lever and said pawl for providing a lost motion connection between the friction lever and the pawl, and an operating member pivotally connected to the transfer lever for rotating the transfer lever and the friction lever so as to operate said pawl.

13. A knee lock for artificial limbs including a fixed bracket connected to a limb member, a pin rotatably connected to said bracket, a, friction lever carried by said pin on one side of said bracket, a transfer lever carried by said pin on the opposite side of said bracket, 9, locking pawl pivoted to the knee lock above said bracket, a rod connected to said pawl and extending loosely through said friction lever, a coil spring surrounding said rod and confined between said friction lever and said pawl for providing a lost motion connection between the friction lever and the pawl, means providing a lost motion connection between the transfer lever and the friction lever, and an operating member pivotally connected to the transfer lever for rotating the transfer lever and the friction lever so as to operate said pawl.

14. An artificial limb having in combination, a thigh member provided with a catch, a calf member pivotally connected to said thigh member, a foot member pivotally connected to said calf member, a knee lock mechanism connected to the calf member and including a pawl arranged to be moved into and out of engagement with said catch, a control bracket connected to the calf member, a friction member rotatably connected to said bracket, means operatively connecting said friction member to said pawl, a transfer member rotatably connected to said bracket, means operatively connecting said transfer member to said friction member, an operating rod connected at its lower end to said foot member, and means connecting the upper end of said rod to said transfer member, the parts being constructed and arranged so that upon rocking movement of the foot member in one direction to cause the operating rod to actuate the transfer member and the friction member to move the pawl into engagement with the catch and upon movement of the foot :member in an opposite direction to actuate the operating rod, the transfer member and the friction lever so as to disengage the pawl from the catch. 15. An artificial limb as called for in claim 14 in which the transfer member and the friction member have coacting means for providing a lost motion connection between said members.

JAMES E. HANGER, III.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 9,202 Russell Aug. 17, 1852 2,071,711 Sprouls Feb. 23, 1937 FOREIGN PATENTS Number Country Date 171,613 Great Britain Nov. 24, 1921 518,258 Great Britain Feb. 21, 1940

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