US2709007A

US2709007A - Car coupler

Info

Publication number: US2709007A
Application number: US125323A
Authority: US
Inventors: William J Metzger
Original assignee: National Malleable and Steel Castings Co
Current assignee: National Malleable and Steel Castings Co
Priority date: 1949-11-03
Filing date: 1949-11-03
Publication date: 1955-05-24
Anticipated expiration: 1972-05-24

Description

May 24, 1955 w. J. METZGER 2,709,007

CAR COUPLER Filed Nov.` 3. 1949 4 Sheets-Sheet l lll I FE. 2o.

IN VEN TOR.

WILLIAM u. rz ER QQ M May 24, 1955 w. J. Ml-:TzGER CAR COUPLER 4 Sheets-Sheet 2 Filed Nuv. 3. 1949 INVENTOR.

WILLIAM J. METZGER "ATTORNEY Mlay 24, 1095945 w, J, METZGER 2,709,007

v CAR coUPLER Filed NGV. 3. 1949 4 Sheets-Sheet 3 INVENTOR. WILLIAM WETZGER WM @f M A T TOF/VE Y May 24, 1955 w. J. METZGER 2,709,007

CAR COUPLER Filed Nov. 3. 1949 4 Sheets-Sheet 4 INVEN WILLIAM J. METZG.

A TTRNE Y United States Patent O National Malleable and Steel Castings Company,

Cleveland, Ohio, a corporation of Ohio `Application November s, 1949, serial No. l125,323

9 claims. (c1. 213-146) This invention relates to a railway car coupler, and more particularly to anti-creep means forthe lock and to an `improved lock operating'and knuckle throwing mechanisrn.

In the past, the vcoupler lock anti-creep mechanisms Vwere directed primarily to preventing undesired upward creeping or movement of the coupler lock due to the bouncing or vertical movements of the coupler in service. It has been found however, that such mechanisms generally failed to prevent the lock from moving to unlocked position under service conditions where the, coupler was subjected to the combination of end or 'buiiing shock and vertical shock, such as occurs during a sudden run in of slack betweencars having drooped couplers. Such a condition may cause suiiicient rotation of .the lock operating mechanism to release momentarily the. anti-creep so that uponthe vertical shock imparted to the coupler, the lock will be thrown upwardsto .unlocked position.

My invention provides a lock operating mechanism which serves to prevent unlocking of the lock even under the above named condition `of combined end and vertical shock applied Vto the coupler. The inertia of the lock is utilized under such conditions to assure that the anticreep will remain effective to preclude unlocking of the lock. However, during desired actuation of the uncoupling mechanism, the anti-creep is positively released with an accelerated motiony to permit movement of the lock to unlocked position. A feature of the lock operating mechanism is the provision of an arrangement for unlocking the lock and moving the knuckle to open position with a minimum of rotational movement of the uncou.- pling rod. A further feature of the inventionresides in the provision of improved contact between the lock leg andthe knuckle thrower to increase the power Vapplied to the thrower during the knuckle throwing operation.

Ctherfeatures. anduadvantages of the .invention will be set forth in .the following description taken in conjunction with the drawings in which:

Fig. 1 is a longitudinal vertical sectional view of a coupler embodying the. invention, showing the parts in locked position.

Fig. 2 is atransverse vertical sectional View taken along line 2-2 of Fig. 1.

Fig, 2a is a `detail view of the lock lifter link.

Fig. 3` is a partial view in longitudinal vertical .section showing the anti-creep moved out of active position by the actuation of the rotor lever.

Fig. 3a is a fragmentary sectional view taken along line .3a-3a of Fig. 3.

' Fig, 4 is a ,partial view in longitudinal vertical section showing the lock in lock-set positiomwithv the other parts in reposed position.

Fig. Sis a partial view in longitudinal vertical section showing `the lock leg in engagement with the knuckle thrower during the process of opening the knuckle.

` Fig. V6 is` al partial view 'similar to Fig'. 5 butl showing the partsl in ffull knuckle thrown position.

`Fig. 7 is a partial View, corresponding to Fig. 1, show- 2,709,007 Patented May 24, 1955 ICC ing the anti-creep vengaged to preclude further upward movement of the lock.

Fig. 8 is a partial view in longitudinal vertical section showing the anti-creep engaged under the conditions of combined end and vertical shock applied to the coupler.

Fig. 9 is a horizontal sectional view showing the parts in locked position.

Figs. 10 and 11 are side and end view details of the rotor member.

Fig. 12 is a detailof the rotor lever and also illustrates the end of the lever in its relative position at the beginning of the knuckle throwing operation, and in its relative position when the knuckle is in opened position.

Fig. 13 is a fragmentary sectional View taken along line 13-13 of Fig. 2.

Fig. 14 is a fragmentary sectional view taken along line 14-14 of Fig. 5. v

Fig. 15 is a fragmentary sectional view taken along line 15-15 of Fig. 1.

Referring to the drawings, the coupler comprises a head 10 and a knuckle 12 which is pivotally connected to the head by means of the usual pivot pin 14. The knuckle comprises a tail portion 16 which, when the knuckle is in closed position, extends into a chamber 18 in the coupler head. Tail 16 may be formed with a vertical lock engaging face 20 and a laterally extending projection or shelf 22. The knuckle is held in closed position by a lock 24 which in locked position rests on shelf 22 and engages face 2i? on the knuckle tail, and wall 26 on the coupler head. A chamber 28 is provided in the coupler head above the lock 24 for receiving the lock during lifting thereof to permit opening of the knuckle. The lock has a depending portion or leg 30 which extends into an opening 32 in the lower portion of the coupler head.

Within opening 32 and lying adjacent lock leg 30, isV

the lock lifter link 34, which is pivotally and slidably connectedv to the lock leg by means of a trunnionA 36 which is received in an upwardly and rearwardly sloping slot 38 in the lower portion of the leg. Lifter link 34 is formed with an anti-creep arm 40 which extends upwardly from trunnion 36 and underlies shelf 22. The upper end of arm 40 is preferably rounded and is adapted to engage the underside 41 of shelf 22 in the event that lock 24 creeps upwardly or is accidentally bounced upwardly to limit further movement thereof. ward portion of surface 41 is curved downwardly as at 41a to make the anti-creep more effective. Link 34 also has a downwardly extending arm 42 which is received in the bifurcated forwardly extending portion 44 of rotor lever 46 and is pivotally connected thereto by means of a pin 48. As may be seen in Fig. l, link 34 occupies a substantially vertical position with trunnion 36 disposed directly above pin 48 when the coupler parts are in normal locked position.

The rearward end 5i) of lever 46 is pivotally connected to the underside of the coupler head by means of a rotor member 52 which is mounted in the spaced depending

flanges

54 and 56 on the coupler head. It will be observed that the axis of member 52 is disposed at an elevation intermediate that of trunnion 36 andpivot pin 48. It will be also noted that the distance from the axis of pin 48 to the axis of member 52 about which lever 46 rotates, is substantially greater than the distance from the airisy of pin 48 to the axis of trunnion 36. This relationship of the parts in conjunction with the disposition of trunnion 36 directly above pin 4S assures 'a quick withdrawal of anti-creep arm 4t) rearwardly from beneath shelf 22 as lever 46 is rotated to raise the lock,

Rotor member 52 as may best be seen in Figs. l0 and 11, comprises a key portion 58 which is received in a corresponding opening in portion S0 of the rotor lever,

The rearand

cylindrical bearing portions

60 and 62 which are adapted to be received in

anges

54 and 56 respectively.

Bosses

64 and 66 are formed on the inner side of flanges S4 and 56 to provide increased bearing areas for

cylindrical portions

60 and 62. Rotor member 52 is provided with a flange 68 which, when the coupler parts have been assembled, is disposed between flange S4 and a retaining flange 70, thereby preventing the rotor member from being displaced axially from its normal position. An eye portion 72 is provided at the end of the rotor member for receiving the hooked end of an uncoupling rod 74 (shown in dot-dash).

The operation of the parts to effect intentional unlocking of the coupler will now be described. Starting with the coupler parts in normal locked position as seen in Fig. l, as rotor member 52 is rotated through actuation of the uncoupling rod, rotor lever 46 is caused to pivot in a clockwise direction. The initial pivotal movement of lever 46 moves the lower end oi arm 42 forwardly and upwardly and simultaneously therewith `moves trunnion 36 rearwardly and upwardly to the upper or rearward end of slot 33 in the lock leg as seen in Fig. 3. This operation serves to move the upper arm 40 from beneath shelf 22 on the coupler tail to inactive position by an accelerated motion. lt will be observed that during this movement, link 34 not only pivots about trunnion 36, but is cammed upwardly and rearwardly through the action of slot 38. Thus for a given amount of rotation of the rotor lever 46, a substantial withdrawal rearwardly of arm 48 is effected. The lock is now free to be moved to unlocked position, and upon rotation of lever 46 from its position in Fig. 3, an upward and rearward force is directed by trunnion 36 against the lock leg. Since the lock leg is normally in engagement with rear wall 7S of opening 32, the initial movement of the lock is vertically upwards. However, after the lock is raised to the position wherein leg 3i) is clear of wall 75, then the leg is moved both upwardly and rearwardly until shoulder 76 is above arm 78 of the knuckle thrower, after which upon release of the uncoupling rod, the lock will be supported by shoulder 76 resting on arm 78. This is the lockset position as shown in Fig. 4, in which the parts are shown at rest, with trunnion 36 occupying the lower end of slot 38. As the lock is actuated further from the lockset position, the surface 80 of the lock leg now moves into contact with arm 78 of the knuckle` thrower. ln Fig. 5, surface Sil has just come into contact with arxn 78. Rotation of lever 46 from this position continues to urge the lock upwardly until fulcrurn lug 82 on the lock engages abutment 83 in the coupler head. Thereafter, the lock pivots about abutment 83 and lock leg 3i) moves arm 78 rearwardly, thereby rotating the knuckle thrower and effecting pivoting of the knuckle toward open position through the action of arm 84 at the other end of the thrower against pad 85 on the knuckle. As rotation of lever 46 continues, the lock pivots a predetermined amount about abutment 83 until the top portion S6 of the lock moves into engagement with a secondary pivot pointy 88 disposed about abutment 83, whereupon the lock pivots about the point 8S as the knuckle throwing operation progresses. A guide rib 89 serves to pre vent the upper end of the lock from sliding forwardly during this operation. lt will be apparent that the force now directed by the lock leg against arm 78 will be more nearly in a horizontal direction, as compared with its direction when the lock pivots about abutment 83, thereby exerting a greater' effective force against the knuckle thrower during the final movement of the knuckle toward open position. As rotor lever 46 is rotated, the lock continues to pivot about portion 88 until the knuckle is fully thrown open as seen in Fig. 6. This secondary fulcrum action constitutes a feature of the lock operating mechanism.

lt will be observed that during the unlocking operation when trunnion 36 occupies the upper or rearward end of slot 38, as seen in Fig. 3, it is disposed rearwardly of pin 48 and therefore a rearward as well as an upward force is imparted by the trunnion to the lock ieg during actuation of the link by the rotor lever. In addition, the center of gravity of the lock is forward of the line of force passing through pin 48 and trunnion 36, thus tending to swing the lock leg rearwardly when the trunnion is in the upper end of slot 38 and the lock is being lifted thereby. This action becomes of considerable importance in the event the lock leg in service becomes displaced forwardly in engagement with front wall 90 of opening 32. In such a case as rotation of lever 46 moves trunnion 36 into engagement with the upper end of slot 38 the trunnion remains disposed rearwardly of pin 48 and also the center of gravity of the lock still remains forward of the line of force passing through pin 48 and trunnion 36, thus assuring that the initial movement of the lock leg is rearward until it engages rear wall 75, as seen in Figs. 1 and 3. This permits arm 40 to be swung from beneath shelf 22 upon further rotation of lever 46, thereby releasing the anticreep to the lock. Thus the mechanism initially provides for positive rearward movement of the lock leg upon actuation of the rotor lever so that the anti-creep will be released under all possible positions of the lock leg in opening 32.

In Fig. 7 is shown the manner in which arm 40 of lock lifter link 34 cooperates with surface 41 on the knuckle tail to limit upward creeping or accidental upward movement of the lock in service. The lock has been moved bodily upwards until the upper end of arm 40 engages surface 41 thereby preventing further upward movement of the lock. In this position trunnion 36 occupies the lower end of slot 38 as in reposed position of the parts (Fig. 1). Consequently any movement of arm 40 rearwardly from the position shown in Fig. 7 will necessitate downward movement of the lock due to the camming action of trunnion 36 in slot 38 as the link pivots about pin 48. In addition, the downward curvature of surface 41, at 41a, serves to increase the amount of downward movement of the lock in order that arm 40 can be moved from beneath surface 41a. It is thus seen that upward movement of the lock to the position in which the knuckle can be opened is effectively prevented.

In Fig. 8 is illustrated the manner in which the anticreep functions to limit upward movement of the lock under the conditions of combined end and vertical shock that may occur in service, for example, during a lrun in of slack between cars having drooped couplers. Under this condition, the end shock will cause the lock leg to move forwardly into engagement with front wall 90 of opening 32 and rotor lever 46 may be caused to rotate until trunnion 36 of the lifter link is raised to the upper end of slot 38. Normally when the rotor lever is actuated intentionally by means of the uncoupling rod and trunnion 36 is displaced to the upper end of slot 38, the end of arm 40 is clear of shelf 22 as seen in Fig. 3. However, with the lock displaced forwardly in engagement with front wall 90, the lifter link cannot be rotated to a position in which arm 40 is clear of shelf 22. Therefore, as the vertical shock causes the lock to be raised, a portion of the upper end of arm 40 still remains beneath shell 22 and engages undersurface 41 to prevent further J upward movement of the lock. Thus, while rotation of rotor lever 46 under the end shock may cause the upper arm 40 to be rotated rearwardly and trunnion 36 of the lock lifter link to occupy the upper end of slot 38, simultaneously therewith the inertia of the lock leg causes the latter to engage wall 90 and move the lifter link bodily forwardly to a point in which arm 40 is partially beneath ledge 22. The clearance provided as at x between front wall 90 and the opposing side of the lock leg, with the parts in normal locked position as in Fig. 1, is such as to be approximately equal to the amount of overlap between anti-creep arm and knuckle shelf 22 under the condition of the parts as shown in Fig. 8. It will be seen therefore, that even 'under the conditions of combinedend and vertical shock, the lock anti-creep is eective to preclude upward movement of the lock to a position in which the knuckle is free to be opened.

A feature of the invention resides in so forming link 34 that upper arm 40 in the region of trunnion 36, has its side 92 offset laterally from the side 93 of lower arm 42, so that the upper surface of the trunnion is increased `in lateral extent as at 94. The lock leg is provided with a lateral projection 95 which extends the upper surface of the upper end of sl'ot 38 and thereby is adapted to engage surface 94 of the trunnion during operation of the mechanism to unlock the coupler, as in Fig. 3a. in addition to reducing wear on the trunnion and slot engaging surfaces, also relieves the trunnion of a substantial amount of shearing stress, since during raising of the lock with portion 94 ofthe trunnion engaging projection 95, lower arm 42 is subjected to a direct cornpressive force. The increased lateral extent of trunnion 36 also servesto stabilize the lock during raising of the latter by the actuation of the uncoupling mechanism.

It will be observed that the lower rearward side of the lock leg is relieved as at96 (Figs. 14 and 15 thereby forming a projection 98 on the outer side of the lock leg on which is located the knuckle thrower engaging surface 80. This assures that the force of the lock leg against arm 78 of the knuckle thrower will be directed thereto at a point a maximum distance from the pivotal axis of the thrower. Also rear wall 78 of the coupler head is recessed as at 100 to receive projection 98 when the lock is in locked position, as Seen in Figs. l and l5. In this position, a clearance exists between surface 80 of projection 98 and the opposing surface 102 on the coupler head, While surface 96 of the Vlock leg engages rear wall 75. Thus in locked position of the coupler, no Wear takes place on surface 80.

Surface 80 is preferably rounded in a horizontal direction so as to provide improved surface contact with thrower arm 78. Also the lower portion of surface 80, as at 80a, is formed so as to slope downwardly and forwardly when the lock is in locked position so that when this surface is in contact with the knuckle thrower near the completion of the knuckle throwing operation, itis disposed approximately in a vertical position. This in conjunction with the pivoting of the lock about pvot point 88 results in the direction of a horizontal force to the knuckle thrower.

The mechanism, in addition to providing effective anticreep means for the lock, also operates to unlock and open the knuckle with minimum rotation of the uncoupling rod. Moreover, while the total rotation of the rotor lever is kept to a minimum, the portion thereof which occurs during the opening of the knuckle has been increased, resulting in a gain in leverage which makes for easier operation of the mechanism. In Fig. l2, rotor lever 46 is shown in position A wherein the coupler is locked, as in Fig. l. Position B corresponds to the beginning of the opening of the knuckle and position C corresponds to the fully opened position of the knuckle. Thus, from position B to C the rotor lever moves through an angle of about 251/2 degrees, while the total angle of rotation is about 84 degrees. The position of the rotor lever corresponding to release of the anti-creep is only about 71/2 degrees from position A and therefore is not shown.

The following is a comparison of the angular movement of the rotor lever 46 with that of the rotor lever of the existing A. A. R. standard type H tightlock coupler as shown in the 1946 Car Builders Cyclopedia, page 918.

This feature l Air-il iis'.

It will be observed from the above that to release the anti-creep of the present application requires a rotation olv the yrotor lever of less than one-fourth that necessary to release the anti-creep of the existing coupler. Also it is significant that the rotor lever of the present application rotates several more degrees than that of the. existing coupler to open the knuckle once this operation begins. Moreover, the total rotation of the rotor lever is considerably less than that for the existing coupler.

To assemble the coupler, the knuckle thrower is rst applied -to the couplerl head through the front opening thereof. Next the rotor lever 46 to which the lock lifter link 34 has previously been connected by pin 48, is applied to the head with the link hanging downwards. In this position of the rotor lever, rotor member 52 can be inserted through franges 54, S6 and the key receiving opening in the rotor lever until ange 68 engages the outer side of depending ange 54 on the head. Thereafter, the lifter link is raised up through the lock receiving opening 32' in the head into a position in which arm 4.0 extends Vthrough the front opening in the head. During the latter operation, the rotorlever is pivoted to a position in which flange 68 thereof is between retaining flange '70 and dependingange 54. The lock leg is next entered through the front ot' the coupler and trunnion 36 of the lifter link is hooked into slot 38 of the lock leg. Then the lock is lowered Ainto the lock receiving opening 32, after which it is vraised to the lock set position, with shoulder 76 resting on the knuckle thrower arm 7S. The assembly is completed with the application of knuckle 12 to the head.

Disassembly of the coupler is accomplished by performing each of the above steps in reverse order.

The'terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, inthe use of such terms and `expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

What I claim is:

l. fIn a car coupler having ahead and a knuckle pivoted to said head, said knuckle having a tail, a vertically movable lock for said knuckle, said lock having a leg extending downwardly rthrough an opening in said head, said opening having front and rear walls so spaced apart as to` provide clearance `for limited movement of said lock leg longitudinally of the coupler, a rotor lever pivoted to theunderside of said head, and a lock lifter link having a trunnion intermediate its ends, said leg having an elongated slot extending upwardly and rearwardly, said trunnion being received in said slot and normally occupying the lower end thereof, said link having its lower end connected to said lever at a point substantially directly below said trunnion, said link connections and said slot being so arranged that with said trunnion in the lower end of said slot the upper end of said link underlies a portion of said tailwhen said lock leg is disposed against said front wall or against said rear wall of said opening, and with said trunnion in the upper end of said slot the upper end of said link underlies a portion of said tail only when said lock leg is in engagement with said front wall of said opening.

2. In a car coupler having a head and a knuckle pivoted to said head, said knuckle having a tail, a vertically movable lock for said knuckle, said lock having a leg extending downwardly through an opening in said head, a rotor lever pivoted to the underside of said head, and a lock lifter link having a trunnion intermediate its ends, said link comprising a lower arm and an upper arm, said lower arm being pivotally connected to saidlever, the upper end of said lower arm having a portion curved to correspond with the upper surface of said trunnion and forming an extension thereof, said upper arm extending upwardly from said lower arm adjacent said curved portion and underlying a portion of said tail, said lock leg having a slot for receiving said trunnion, said lock having a projection on a side thereof and forming an extension of the upper surface of said slot for engagement with said curved portion on said lower arm during actuation of said lever to raise said lock.

3. In a car coupler having a pivoted knuckle and a movable lock, said knuckle having a tail, a lock operating mechanism comprising a rotor lever pivoted to said coupler, and a lock lifter link having its lower end pivoted to said lever, the upper vend of said link normally underlying a portion of said tail, a laterally extending trunnion intermediate the ends of said link, a side of the upper portion of said link being Offset laterally from the corresponding side of the lower portion of said link to provide an extension of the upper side of said trunnion surface, said lock having a leg formed with an opening to receive said trunnion, said leg having a lateral extension providing a continuation of the upper surface of said opening, said trunnion surface being adapted to engage said surface on said lateral extension of said lock leg during actuation of said lever to raise said lock.

4. A lock lifter link for a car coupler, said link comprising a lower arm adapted for pivotal connection to 'a rotor lever, an upper arm extending upwardly from said lower arm and adapted to underlying a portion of a coupler knuckle to form an anti-creep for the lock, and a laterally extending trunnion at the juncture of said upper and lower arms adapted to be received in a slot in tne lock leg, said upper arm having a side offset laterally from the side of said lower arm to provide an extension of the upper surface of said trunnion, said extension of said trunnion surface being adapted for engagement with a lateral extension of the surface of the slot in said lock leg during actuation of the rotor lever to raise the lock.

5. A lock lifter link for a car coupler, said link comprising a trunnion portion adapted to be received in a slot in the leg of the coupler lock, an arm extending upwardly from said trunnion portion and being adapted to underlie a portion of a coupler knuckle to form an anti-creep for the lock, and another arm extending downwardly from said trunnion portion adapted for pivotal connection to a rotor lever, said lower arm being wider adjacent said trunnion than said upper arm, said widened portion of said lower arm providing an extension of the upper surface of said trunnion, said extension of said trunnion surface being adapted for engagement with a lateral extension of the surface of the slot in the lock leg during actuation of said rotor lever to raise the lock.

6. In a car coupler having a head and a knuckle pivoted to said head, said knuckle having a tail, a vertically movable lock for said knuckle, said lock having a leg extending downwardly through an opening in said head,

a rotor lever pivoted to the underside of said head, and a lock lifter link having a trunnion intermediate its ends, the lower end of said link being pivotally connected to said lever, the upper end of said link underlying a portion of said tail, said leg having an upwardly and rearwardly extending elongated slot for receiving said trunnion, said slot being so disposed that upon initial rotation of said lever the camming action of said slot against said trunnion withdraws the upper end of said link from beneath said shelf with an accelerated motion, said lock leg normally engaging the rear wall of the opening in said head when said knuckle is in closed position and being spaced rearwardly from the front wall of the opening, said leg being adapted to move forwardly into engagement with said front wall upon the application of an end shock to the coupler, in which position the camming action of said slot against said trunnion is ineffective to withdraw the upper end of said link entirely from beneath said shelf portion,

7. in a car coupler having a head and a knuckle pivoted to said head, said knuckle having a tail, a vertically movable lock for maintaining said knuckle in closed position, said lock having a leg extending downwardly through an opening in said head, said opening having front and rear walls spaced apart a predetermined amount to provide clearance for movement of said lock leg longitudinally of the coupler, a rotor lever pivoted to the underside of said head, and a lock lifter link having a horizontal trunnion intermediate its ends, said leg having an elongated slot extending upwardly and rearwardly, said trunnion extending into said slot and occupying the lower end thereof when said knuckle is in closed position and the parts are at rest, the lower end of said link being pivotally connected to said lever, the upper end of said link underlying a portion of said tail for all positions of said lock leg in said opening in a direction longitudinally of the coupler and being adapted to be withdrawn from beneath said tail portion upon intentional actuation of said lever, said leg upon the application of an end shock to the coupler being adapted to move forwardly into engagement with said front wall, in which position actuation of said lever is ineffective to withdraw the upper end of said link entirely from beneath said tail.

8. A lock for the knuckle of a car coupler, said lock comprising a depending leg adapted to extend downwardly into an opening in the coupler, said leg having an elongated transverse slot extending upwardly and rearwardly, said slot being adapted to receive a trunnion of an associated lock lifter link and having a surface in its upper end for engagement by said trunnion, said leg being formed with a lateral projection adjacent the upper end of said slot which provides a continuation of said surface in the upper end of the slot.

9. A lock constructed in accordance with claim 8 in which said projection is formed on the side of said leg facing the associated link.

References Cited in the le of this patent UNITED STATES PATENTS 2,083,422 Bazeley June 8, 1937 2,217,722 Bazeley Oct. 15, 1940 2,340,818 Metzger Feb. l, 1944 2,350,470 Metzger June 6, 1944 2,393,912 Kayler Jan. 29, 1946 2,585,958 Metzger Feb. 19, 1952