US2615403A

US2615403A - Railway truck with damping means

Info

Publication number: US2615403A
Application number: US592678A
Authority: US
Inventors: Claude L Orr; James C Settles
Original assignee: Buckeye Steel Castings Co
Current assignee: Buckeye Steel Castings Co
Priority date: 1945-05-08
Filing date: 1945-05-08
Publication date: 1952-10-28
Anticipated expiration: 1969-10-28

Description

Oct. 28, 1952 c. ORR ETAL RAILWAY TRUCK WITH DAMPING MEANS 5 Sheetg-Sheet 1 Filed May 8, 1-945 Elmo/1M 61L.0rr,

C- L. ORR ET AL RAILWAY TRUCK WITH DAMPING MEANS Oct. 28, 1952 I v 3 Sheets-Sheet 2 Filed May 8, 1945 A wT m wmw Oct. 28, 1952 c. 1.. ORR arm.

RAILWAY TRUCK WITH DAMPING MEANS 3 Sheets-Sheet 3 Filed May 8, 1945 Patented Oct. 28, 1952 RAILWAY TRUCK WVITH DAMPING S Claude L. Orr and James C. Settles, Columbus, Ohio, assignors to The Buckeye ,Steel Castings Company, Columbus, Ohio Application May 8, 1945, Serial No. 592,678

27 Claims. 1

' This invention relates to improvements in railway trucks, and more particularly to damping means therefor;

An object of the invention is to provide damping means applicable to a bolster end or arm of limited width without impairing the strength of the bolster.

Another object is to provide a damping means comprising wedges and wedge actuating springs arranged in pockets formed in the bolster end, and in which the axes of the actuating springs are'substantially parallel to cooperating inclined surfaces of the friction wedges and bolster pockets.

With the foregoing objects outlined, and with other objectsin view which will appear as the description progresses, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

In the drawings:

Figure l is a side elevation of a four wheel truck provided with our improved damping means;

' Figure is an enlarged side elevation, partly in vertical section, of the medial portion of such truck.

Figure 3 is a transverse horizontal sectional view on the line 3-3 of Figure 2.

Figure 4 is a vertical transverse sectional view on the line 4-4 of Figure 2.

Figure 5 is aside elevation of a portion of a six wheel truck ofthe equalizer type, with the invention incorporated therein.

Figure 6 is a topplan view of the structure shown in Figure 5 and partly in transverse horizontal section, the section being taken on the line 6-6 of Figure 5.

Figure '7 is a sectional view taken on the line 1-1 of Figure 3 with the spring removed.

Referring to Figures 1 to 4, inclusive, 1 designates a truss type side frame of a four wheel truck provided with spaced bolster guide columns 8 at opposite sides of a bolster opening 9. The spring seat 10 of each side frame supports truck springs l I positioned within the bolster opening. A bolster end or arm 12 extends into the bolster opening, rests on the springsand is guided by the columns 8. At each side of the bolster arm or end, a pocket I3 is formed for the receptoin of a friction wedge l4. Each wedge has a vertical face IE to frictionally engage'a vertical wear plate l6 fixed to the guide column. The wedge also has an inclined inner face l'lv slidably engaging a complementary inclined face It formed'by'the bolster and arranged in the pocket. The face I! on each wedge slopes towards the vertical face I5 in proceeding upwardly from the base portion of the wedge so that the upper end or apex part is of less width measured transversely of the bolster than that portion of the wedge adjacent the bottom member or web 4| of the bolster end or arm l2. As may be seen from Figure 2, the complementary inclined surfaces l1 and I8 diverge upwardly and each of the surfaces 11 is slightly convex to allow the friction wedge to rock relatively to the bolster and to permit the bolster to rock relatively to the side frame.

The bottoms of the pockets are provided with inclined surfaces l9 which are substantially perpendicular respectively to inclined surfaces l8 and converge upwardly and serve to support the bases of spring 20, preferably of the coil type. The bottom web H of the bolster is formed with an inverted substantially V-shaped notch 45 in the mid-portion providing the inclined spring seat surfaces l9 within the pockets. A vertically reinforcing web 46 integral with the top web 22 of the bolster extends downwardly therefrom and joins the upper ends of the spring seats [9. The upper ends of the springs bear against surfaces 2| in the tops of the'wedg es, parallel to the sur: faces l9. With this arrangement, it is obvious that the springs 20 diverge upwardly and are substantially parallel to the inclined surfaces I! and I8of the wedges and bolster. This arrangement of the actuating springs 20 with relation to the inclined surfaces l1, l8 has severaladvantages. First, relative motion between each wedge and bolster, as during application of the wedge to, or removal from, the bolster, or dueto wear in service, takes place in the direction of the inclined surface which is parallel to the spring axis and, therefore, does not cause any lateral shearing action on the spring such as would occur with the axis of the spring in any other position. Second, the energy absorbed by the friction force between the vertical face l5 of the wedge and the contacting column surface I6 is dependent upon the pressure exerted upon the column surface by the wedge. With the wedge actuating spring in inclined position, the horizontal component of the spring force is resisted entirely by the side frame column, thereby permitting the use of a smaller spring for a predetermined amount of damping than would be necessary if the axis of the spring is vertical. Third, the smaller spring and its inclined position permits the use of a comparatively wide top portion 22 of the 3 bolster between the pockets, thereby strengthening the bolster at this point.

In order to apply the friction wedges and the springs to the bolster, holes 23 and '24 are provided in the wedges and bolster, respectively, on the axes of the springs 22, for insertion of bolts, not shown, by means of which the wedge springs can be compressed until the width over the two wedges at the same end of the bolster is less than the width between the bolster guide columns 8 When the wedge springs are compressed in this way, rods, not shown, can be inserted through holes 25 in the bolster pocket walls, and holes 26 in the wedges, which holes will now be in alignment. The bolts can then be removed and the bolster applied to the side frame, after which the rods can be removed to permit the wedge springs to expand so that the vertical friction surfaces 15 of the wedges bear against the wear plates I6 of the columns. v r

As heretofore mentioned, the surfaces I! of the friction wedges are each formed with a slight convex curve to permit the wedges to rock slightly with respect to the bolster and thereby align themselves with the side frame columns. This is of particular importance in the equalized type of six wheel and eight wheel trucks, in which the equalizer action causes the-side framesto rotate slightly in a vertical plane with respect to the bolster.

In Figures 5 and 6., We have shown the invention embodied in a six wheel truck of the equalized type, and it is obvious that it can be incorporatedin an eight wheel trucko'f this type, such as is shown in the patent to Johnson et 211., 2,235,214. 7 f

Referring to Figures 5 and 6, Z'Idesignates anend side frame member of a six wheel truck, having a projecting born 28 to extend over the middle axle of the truck and be pivotally connected, .at 29, to one of the arms 30 of the equalizer. As is usual in this type of truck, the arms of the equalizer are offset, as shown in Figure 6, so thatv the arm '31 maybe pivotally connected to the horn of a similar side frame member 21 (not shown). In this embodiment, the frame member 21 has a bolster opening 32 to receive an end or arm 33 of a "bolster system, and the arm rests on truck springs 34 carried by the side frame member 21. The damping means, indicatedgenerally at 35, may be identical with the damping means illustr'ated'in Figures 1 to 4,,inelusive.

From the foregoing, it is believed that the construction, operation and advantages of our improved damping means may be readily understood, and we are aware that changes may be made in the details disclosed without departing from the spirit of the invention as expressed in the following claims.

'What we claim and desire to secure by Letters Patent is: a

1. A bolster'ad'aptedto cooperate with damping means for railway trucks, said bolster being provided with opposite side pockets, upwardly diverging surfaces arranged in the pockets between the top and bottom of the bolster, and upwardly converging spring "engaging surfaces positioned in the pockets at the bottom of the bolster and arranged substantially at right angles to 'saiddiverging surfaces.

2. In a railway car truck, a side frame provided with bolster guide columns arranged at opposite sides of a bolster opening, a bolster portion extending into said opening and having oppositely 4 disposed pockets, each pocket confronting one of the guide columns, the bolster portion where it extends into said opening having a top member and a bottom member, one of said members extending transversely of the bolster from one column to the opposite column and the other member being of less transverse width than the other, substantially vertical reinforcing means arranged between said members and forming a back wall for each of the pockets, said pockets having surfaces diverging in a vertical plane, springmeans supporting said bolster portion from the side frame, friction wedges arranged in said pockets and frictionally engaging said columns and said diverging surfaces, and other spring means in said bolster portion positioned substantialiy parallel to said diverging surfaces and yieldingly urging the wedges against said colums.

3. In a railway car truck, a side frame provided with bolster guide columns arranged at opposite sides of a bolster opening, a bolster portion ex: tending into said opening and having oppositely disposed pockets, each pocket confronting one of the guide columns, the bolster portion where it extends into said opening having a top member and a bottom member, the bottom one of said members extending transversely of the bolster from one column to the opposite column and the top member being of less transverse 'width than the other to expose the upper ends of the pockets, substantially vertical reinforcing means extending lengthwise of the bolster, arranged between said members and forming a back wall foreach of the pockets, said pockets having upwardly diverging surfaces arranged between said members and the bottom member having surfaces converging toward said reinforcing means, spring .mearm supporting said bolster portion from the side frame, friction wedges arranged in said pockets and frictionally engaging said columns and said diverging surfaces, and other spring means in said bolster portion, bearing against said converging surfaces and the wedges, and positioned substantially parallel to said diverging surfaces for yieldingly urging the wedges against the columns. I

4'. In a railway car truck, a side frame provided with bolster guide columns, arranged .at opposite sides of a bolster opening, a bolster portion extending into said opening and having oppositely disposed pockets, each pocket confronting one of the guide columns, the bolster portion where it extends into said opening having a top member and a bottom member, one of said members extending transversely of the bolster from one column to the opposite column and'the other member being of lesstransverse'width'thanthe other, substantially 'vertical.. reinforcing means arranged between said'members and forming a back wall for each of the pockets, said pockets having surfaces diverging in vertical plane, spring means supporting ,said bolster portion from the side frame, friction wedges arranged insaid pockets and frictionally engaging said columns and said diverging surfaces, the end :of each' wedge adjacent to. the wider member of said .bolster portion-"being wider than-at its opposite end, and otherv spring means in said bolster portion positioned substantially, parallel to said diverging surfaces andyieldingly urging the wedges against said columns.

'5. In a railway car truck, a side frame provide'd with bolster guide columns arranged at opposite-sides of a bolsteropenifiga bolster portion extending into said opening and having oppositely disposed pockets, each pocketconf-rontin one-of the guide columns, the bolster portion'where itextends into said opening having a top member and a bottom member, the bottom one of said members extending transversely of the bolster from one column to'the-opposite column and the-top member being of less transverse width than the other to expose the upper ends of the pockets, substantially vertical reinforcing means extending lengthwise of the bolster, arranged between said. members and forming a back wall for each of 'the pockets, said pockets-having upwardly diverging surfaces arranged between said-members and the bottom member having surfaces converging towardsaid reinforcing means, spring means supportingsaid bolster portion from the side frame, friction wedges arranged in said pockets and frictionally engaging said columns and said diverging surfaces, and other spring means in said bolster portion,- bearing against said converging surfaces and the wedges, and positioned'substantially parallel to said diverging surfaces for yieldingly urging the wedges against the columns, the lower end of each wedge being wider transversely of the bolster than the upper end of the wedge to permit the wedge to extend through the top member at the upper end of the wedge pocket. I i

6. In a railway car truck, a side frame provided with bolster guide columns arranged at opposite sides of a bolster opening, a bolster portion extending into said opening and having oppositelydisposed pockets, each pocket confronting one of the guide columns, the bolster portion having a bottom member extending transversely of the bolster from one column'to the other and forming the bottom of said pockets, a substantially vertical rib arranged between the top and bottom of the bolster and forming a back wall for each of the pockets, the top of the bolster above the pockets being of less transverse width than the bottom member of the bolster where said bolster portion extends in' said opening, said pockets having,

upwardly diverging surfaces arranged J between the top and bottom of said bolster portion, spring means supporting said bolster portion from the side frame, friction wedges extending into said pockets and frictionally engaging said columns and said diverging surfaces, and spring means in'said bolster portion, positioned substantially parallel to said diverging surfaces and yieldingly urging the wedges against said columns. "I. In a railway car truck, a side frame provided with bolster guide columns arranged at opposite sides of a: bolster opening, a bolster portion extending into said opening and having oppositely disposed upwardly diverging surfaces, load supportin springs for supporting the bolster portion from the side frame, friction wedges arranged at opposite sides of the bolster portion and frictionally engaging the columns and said diverging surfaces, the bolster having substantially vertical reinforcing means arranged between said wedges, the bottom of the bolster having surfaces converging toward the reinforcing means, and coil springs arranged in thebolster portion substantially parallel to the diverging surfaces and bearing at one end against the converging surfaces and at the other end-against the upper portions of the friction wedges for yieldingly urging the wedges against said columns. I 1 a the top member being of less transverse width than the bottom member to expose the pockets, substantially vertical reinforcin means joining said members and forming a back wallfor each of otheupockets, said pockets having upwardly divergingv surfaces, load supporting springs for supporting said bolster portion from the side frame, friction wedges arranged in said pockets and frictionally engaging said columnsand said diverging surfaces, said bottom member having surfaces converging toward and merging with said reinforcing means, and coil springs arranged in the pockets for yieldingly urging the wedges against said columns, the coil springs resting on the converging-surfaces, being positioned substantially parallel to said diverging surfaces, and bearin at their upper ends against said wedges.

9. In a railway car truck, a sidev frame provided with bolster guide columns arranged at opposite sides of a bolster opening, a bolster portion extending into said opening and hav-. ing oppositely disposed pockets, each pocket confronting one of the guide columns, the bolster portion where it extends intosaid opening having a top member and a bottom member, the bottom member extending-transversely of the bolster from one column to the opp-ositecolumn and the top member being of less transverse width than the bottom member, the bottom member forming upwardly converging surfaces and said pockets having upwardly diverging surfaces, spring means supporting said bolsterportion from the side frame, friction wedges arranged in said pockets'and frictionally engaging said columns and said diverging surfaces, each wedge at its lower end being wider transversely of the bolster than attits upper end, and other spring means resting on said converging surfaces, positioned substantially parallel to said diverging surfaces and yieldingly urging the Wedges against said columns.

10. In an equalizer type railway truck, a side frame member provided with bolster guide columns arranged at opposite sides of a bolster opening, a bolster portion extending intosaid opening and having oppositely disposed pockets, each pocket confronting one of the guide c01- umns, the bolster portion where it extends. into saidopening having a top member and a bottom member, the bottom member extending transversely of the bolster from one column to the opposite column and-the top member bein of less transverse width than the bottom member to expose the upper ends of the pockets, substantially vertical reinforcing means joining said top andbottom members and forming a back wall for each of the pockets, said pockets having upwardly diverging surfaces, spring means supporting said bolster portion from'the side frame'member, friction wedges arranged in said pockets, frictionally engaging said columns and said diverging surfaces and adapted to extend through the upper endsof the pockets, said bottom member having surfaces converging toward the reinforcing means, the diverging surfaces of the pockets and wedges-being shaped to permit relative rocking motion between the bolster portion and the wedges, and coil springs resting on said converging surfaces, positioned substantially parallel to said diverging surfaces and yieldingly urging the wedges against said columns.

"ll. In a railway car truck, a column member, abolster member resiliently supported for movement along the column member, :said bolster member having a pocket therein open towards the column -member, a friction shoe in said pocket, cooperating inclined surfaces on the shoe and on the bolster member, a helical springropen along the axis thereof compressed between the bolster member and the shoe and arranged in such a position in relation to the cooperating inclined surfaces to urge the shoe towards the guide-column, and said shoe and said bolster member each having a hole therein both aligned with the axis of the helical spring for receiving means to compress the spring. '12. In a railway car truck, a column member, a bolster member resiliently supported for movement along the column member, said bolster member having a pocket therein open towards the column member, a friction shoe in said pocket, cooperating inclined surfaces on the shoe and on the bolster member within the pocket, a spring seat on the shoe substantially at right angles to the inclined surface on the bolster member, a spring seat on the bolster member within said pocket substantially at right angles to the inclined surface on the shoe, a helical spring open along'the axis thereof compressed between said spring Jseats arranged diagonally in the pocket and substantially parallel with respect to the cooperating inclined surfaces to urgethe shoe towards the guide column, and said shoe and said bolster member each having a hole through the respective spring seats both aligned with the axis of the helical spring.

13. In a bolster member for a railway car truck, said bolster member having a pocket a substantially horizontal bottom member, a

substantially vertical reinforcing web extending downwardly from a mid-portion of the top web and connected to the bottom member, and an angular surface extending between the bottom member and the vertical web providing aspring seat with said surface facing an upper corner of the bolster member.

15. In a bolster for a railway car truck, said bolster having a pocket therein open towards one side thereof, a horizontal top web terminating short of the width of the bolster and defining a top of said pocket, a substantially horizontal bottom member for the bolster wider than said top web and defining the bottom of said pocket, a substantially vertical reinforcing web integral with the top web and extending downwardly from a mideportion of the top web and merging with the bottom member providing aback wall for the pocket, and an angularly disposed surface carried by the bottom member and the vertical web providing a spring seat within the pocket.

16. In a bolster for a railway car'truck, a substantially horizontal topweb and a substantially horizontal bottom member, a substantially vertical reinforcing web extending downwardly froma mid-portion of the top member towards the bottom member, an angularly disposed spring seat connecting the bottom member and the vertical web arranged to face an upper corner of the bolster, and said angularly disposed spring seat having an opening therethrough at right angles to the surface of the springseat.

17; In a railway car truck, a column member, a bolster member resiliently supported for movement along the column member, said bolster member having a pocket therein open towards the. column member, a friction shoe in said pocket, a spring seat carried by the bolster within the pocket inclined with respect to a horizontal plane, a spring compressed between said spring seat and the friction shoe urging the friction shoe upwardly and outwardly with respect to the bolster member and towards the guide column, said bolster member having a pin-receiving opening therein :at one side of the spring, and said friction shoe having a pin-receiving opening therein at the same side of the spring.

18. A friction shoe for the damping mechanism of a railway car truck comprising, a wedge member having onerelatively flat straight face, an inclined surface on said wedge member converging towards said fiat face in proceeding towards one end of the wedge member, a spring seat carried by the wedge member at substan-. tially right angles to said inclined surface, and said spring seat having an opening therethrough substantially at right angles to the spring seat.

19. In a bolster for a railway car truck, the side of said bolster having pockets therein open towards both sides of the bolster, a substantially horizontal top web terminating short of the width of the bolster and defining a top of the pockets, a substantially horizontal bottomweb for the bolster wider than the top web and having a generally inverted V-shaped notch in the mid-portion thereof forming inclined spring seats within the respective pockets, and a substantially vertical reinforcing web integral with the top web and extending downwardly and joining top portions of said inclined spring seats.

20.. A railway car truck comprising aside frame with spaced columns, a friction surface on each column intersecting the longitudinal vertical center plane of the side frame, a bolster structure having side walls and spring-supported by said frame between said columns for vertical movement as a unit, said bolster structure containing converging non-compressible walls movable therewith, friction shoe means en-gaging each of said converging walls and the friction surface on the adjacent column, actuating means for said shoe means comprising a pair of springs converging at their inner ends entirely disposed between planes defining the external surfaces of said side walls and seated against the bolster structure, the outer ends of said springs being engaged with said shoe means, andeach of said springs acting on the associated shoe in a line of force angularly related to the associated friction surface and parallel to the associated converging wall whereby said shoe means are tightly wedged between said frictionsurfaces and said converging'walls.

21. In a car truck. a side frame havingspaced 9. columns, a hollow bolsterresiliently supported by, said'frame between said columns and having side ,walls andother walls dividing the bolster into compartments at opposite sides thereof, rigid bolsterisurfaces in respective 'compartmentsjextending toward respective columns, friction-shoes housed in respective compartments engaging said rigid bolster surfaces and adapted to move laterally of the bolster, spring means urging said'shoes outwardly. into frictional engagement with respectivecolumns, said spring means being entirely disposed between the planes of said side walls and housed within the bolster and being compressed between the bolster and shoes, the compressional axes of the spring means associated with the respective shoes lying in a vertical plane at right angles to the longitudinal vertical center plane of the bolster and angularly related to the longitudinal vertical center plane of the bolster and being formed and arranged to afford force components sufiicient to hold the shoes in contact with the rigid bolster surfaces and said columns.

22. In a railway car truck, a side frame having spaced guide columns, a hollow bolster resiliently supported by said side frame for vertical movement as a unit between said guide columns, side walls on said bolster and other walls thereon providing pockets at opposite sides of the bolster, a rigid bolster surface in the respective pockets extending toward the associated guide column, a friction shoe within the respective pockets engaging said rigid bolster surfaces and adapted to move laterally of the bolster outwardly of said pocket, coil springs urging said shoes outwardly into frictional engagement with the respective guide columns, said coil springs being entirely disposed between planes defined by external surfaces of the side walls of the bolster and converging at their inner ends, a spring seat on the bolster within each pocket, each spring seat facing a corner of the bolster and lying in a plane inclined to the horizontal and engaged by an inner end of said coil springs, the outer ends of said springs engaging said friction shoes, said springs being compressed between the spring seats and the shoes with the compressional axes of said springs lying in a vertical plane extending transversely of the bolster and inclined with respect to a horizontal plane, and said springs being arranged to afford force components sufficient to hold the shoes in contact with the rigid bolster surfaces and said guide columns.

23. In a railway car truck, a side frame having spaced guide columns, a hollow bolster resiliently supported by said side frame for vertical movement as a unit between said guide columns, side walls on said bolster and other walls thereon providing a pocket at one side of the bolster, a rigid bolster surface in said pocket extending toward the associated guide column, a friction shoe within said pocket engaging said rigid bolster surface and adapted to move laterally of the bolster and outwardly of said pocket, a coil spring urgin said shoe outwardly into frictional engagement with the associated guide column, a spring seat surface carried by the bolster within said pocket facing a corner of the bolster and lying in a plane inclined to the horizontal and engaged by the inner end of said coil spring, the outer end of said spring engaging said friction shoe and being compressed between the spring seat and the shoe, the compressional axis of said spring lying in a vertical plane extending transversely of the bolster and the compressional axis of said spring sloping with respect to thehorizontal in proceeding outwardly from said spring seat, and said spring being arranged to afford force components suflicient to hold the shoe in contact with the rigid bolster surface and the associated guide column.

24. In a railway car truck, a side frame, a guide column, a bolster member resiliently supported for vertical movements along thev guide column, said bolster member having a pocket'therein open towards the guide column, a friction shoe within said pocket, a spring seat on the bolster within an inner portion of the pocket facing an outer corner of the bolster member, a rigid inclined surface on the bolster within the pocket extending outwardly from the spring seat at an angle to the horizontal towards said outer corner of the bolster member, a coil spring engaging said spring seat at its inner end extending outwardly from the spring seat at an angle to the horizontal and engaging the friction shoeat its outer end, said spring being compressed between the friction shoe and the spring seat urging the friction shoe outwardly of the pocket into frictional engagement with the guide column and into engagement with said rigid bolster surface, the compressional axis of said coil spring lying in a vertical plane extending transversely of the bolster, and said spring being arranged to afford force components sufficient to hold the friction shoe in contact with the rigid bolster surface and the guide column.

25. In a bolster member for a railway car truck, said bolster member having a pocket therein open towards one side of the bolster member, a substantially horizontal top web defining a top of the pocket, a substantially horizontal bottom web defining a bottom of said pocket, a substantially vertical web joining the top and bottom webs, spring seat means within the pocket connected to the vertical web and another of said webs and inclined at an acute angle to a horizontal plane, and said spring seat means having a spring engaging surface facing an outer corner of the bolster member arranged at right angles to a transverse vertical plane of the bolster member.

26. In a bolster member for. a railway car truck, said bolster member having a pocket therein open towards one side of the bolster member, a substantially horizontal top web defining a top of the pocket, a substantially horizontal bottom web defining a bottom of said pocket, means joining the top and bottom webs of the bolster and defining a back wall of the pocket, a rigid surface on the bolster member within the pocket inclined with respect to the horizontal and extending from the back wall towards one corner of the bolster member, a spring seat within said pocket rigid with the bolster member and facing said corner of the bolster member, and said spring seat having a spring engaging surface arranged at right angles to a transverse vertical plane of the bolster member.

27. A friction shoe for a railway car truck, said shoe having a substantially vertical friction face engageable with a member of the truck and a wedge surface angularly disposed with respect to said friction face and engageable with another member of said truck, a spring seat on said shoe for directing the pressure of a spring at an angle to said friction face, said shoe having an opening therein for receiving an implement to shift said shoe out of friction-developing position with respect to said truck, and said shoe having another opening below said spring seat for receiving a pin to maintain said shoe out of friction.- developing position.

CLAU E L. 0mm

JAJSEES. c.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 'Kux Feb. 11, 1919 Number 12 Name Date Bullock Mar. 2, 1915 Layhon Feb; Q, 1232 Couch May 17-", 1938 Davidson Sept. 30 1941 Light Jan. 11, 1944 Davidson e July 4; 1944 Light June 19,1945 Light June. 19, 1945 Lehman Jan, 8, 1946 Cottre'll Jam 20*, 948