US2422201A

US2422201A - Truck

Info

Publication number: US2422201A
Application number: US514033A
Authority: US
Inventors: Leo A Lehrman
Original assignee: American Steel Foundries
Current assignee: American Steel Foundries
Priority date: 1943-12-13
Filing date: 1943-12-13
Publication date: 1947-06-17
Anticipated expiration: 1964-06-17

Description

l5, 1943 3 Sheets-Sheet l Emme E79 94?, L. A. LEHRMAN TRUCK Filed Dec.

Fume Vi, w47., L. A. LEHRMAN TRUCK Filed Dec. l5, 1945 3 Sheets-Sheet 2 HVVENTOR. a@ qe%wwoww Jun@ E?? i947. L.. A. LEHRMAN TRUCK Filed Dec. 13, 1943 3 4Sheets-Sheet 3 O jZ 12@ je @of INVENTOR. jnm

l Patented June 17, 1947 TRUCK Leo A. Lehman, Chicago, Ill., assignor to American Steel Foundries, Chicago, Ill., a corporation of New Jersey Application December 13, 1943, Serial No. 514,033

(Cl. lofi-197) 28 Claims. 1

My invention relates to railway car trucks and more particularly to a truck incorporating a ride control device for frictionally controlling oscillations of the bolster supporting spring group.

The general object of my invention is to provide a ride control truck incorporating a quick wheel change feature whereby the bolster may be removed from the top of the bolster opening in assembled relationship with the friction shoes while a portion at least of the bolster supporting spring group remains in assembled relationship with the side frame.

The present invention is an improvement on the generic design illustrated and described in David M. Light Patent 2,392,599, issued in the United States Patent Ofce January 8, 1946, and a specific object of the present invention is to design a truck of this type wherein a plurality of friction shoes are provided at opposite sides of the bolster in wedge engagement therewith and in frictional engagement with the side frame columns, said shoes being actuated by means of a plate member extending transversely of the bolster and housed therein, said member being resiliently urged into engagement with the friction shoes.

In one embodiment of the present invention,

Y the friction shoe actuator or pressure plate member is connected by means of a bolt and nut assembly extending through the bottom Wall of the bolster to a spring adjustably compressed against said bottom wall, and in another illustrated embodiment of the present invention, the friction shoe actuator affords a seat for its associated spring which is connected to the bottom Wall of the bolster by means of a bolt and nut assembly extending through a central opening in the actuator.

My invention comprehends a bolster of novel form having a pocket in each side thereof defined by inboard and outboard walls or Webs and an intervening rear wall with an opening therethrough for the reception of the adjacent end of the associated friction shoe actuator, a ledge being integrally formed with each of said inboard and outboard walls at one side of said opening and presenting a wedge surface sloping toward the outer extremity of the pocket.

My invention also comprehends a friction shoe of novel form having a main friction Wall integrally formed with spaced ledges presenting Wedge surfaces. A rib extends between the ledges at the upper extremities thereof, said rib being Still another object of my invention is to design a novel friction shoe actuator or pressure plate having at opposite ends and on the bottom thereof spaced abutment surfaces for cooperation with the associated friction shoes under normal operating conditions, said actuator also comprising at opposite ends thereof and on the top thereof wedge surfaces for cooperation with means on the associated friction shoes to maintain the latter in assembled relationship with the bolster during assembly and disassembly of the side frame therewith.

In the drawings:

Figure 1 is a fragmentary side elevation of a railway car truck embodying my invention, portions of the structure being illustrated in section along the longitudinal vertical plane bisecting the side frame.

Figure 2 is a fragmentary top view of the structure shown in Figure 1 with the side frame columns illustrated in section.

Figures 3 to 5 illustratey in detail the novel bolster shown in Figures 1 and 2-, Figure 3 being a fragmentary side elevation, Figure 4 being a fragmentary top plan view thereof, and Figure 5 being a fragmentary sectional View taken in the plane indicated by the line 5-5 of Figure 3.

Figures 6 to 8 inclusive illustrate in detail the novel friction shoe shown in Figures 1 and 2, Figure 6 being a top plan view thereof, Figure '7 being a side elevation thereof, and Figure 8 being a rear elevation taken from the actuator engaging face thereof.

Figures 9 and 10 illustrate a modicationof my invention, Figure 9 being a fragmentary sectional view comparable to Figure 1, and Figure 10 being a sectional view of the bolster and associated friction means illustrating the manner in which the friction means is retained in assembled relationship with the bolster during assembly and disassembly thereof with the side frame.

Figures 1l and 12 illustrate in detail the friction shoe actuator shown in Figures 9 and 10, Figure 1l being a top plan view of the actuator, and Figure 12 being a side elevation thereof.

Describing my invention in detail and referring first to the embodiment thereof illustrated in Figures 1 to 8 inclusive, the side frame comprises a tension member 2 and a compression member 4 merging adjacent each end of the frame with a column 6 dening therewith a bolster opening 8 and the window opening III, the bolster opening 8 having a widened upper portion I2 to permit insertion and removal of the bolster therethrough as hereinafter described. The tension member 2 is of well-known form with the central boxsection portion thereof having a top web I6 widened and formed with an upstanding flange I8 at each of the inboard and outboard sides thereofl to dene a spring seat 20 on the top web I6 for a group of bolster supporting springs diagrammat-l ically indicated at 22, 22, which are seated at 24 (Figure 1) against the bottom wall 26 of the bolster generally designated 28.

The bolster 28 is of box-like form with the before-mentioned bottom wall 26 and the top wall 38, as well as the spaced

side walls

32, 32, and formed in each side of the :bolster is a pocket 34 defined by the inboard and

outboard walls

36 and 38 and the rear wall or web 48 extending therebetween substantially parallel to the

side Walls

32, 32 of the bolster. The web 48 is formed with an opening 42 for the reception of the associated end of the friction shoe actuator or pressure plate as hereinafter described, and at the inboard and outboard sides of the opening 42 are formed the

diagonal walls

44 and 46 merging with the rear wall 48 and with the respective inboard and

outboard walls

36 and 38, each

diagonal wall

44 and 46 sloping downwardly toward the adjacent col` umn 6 and presenting a wedge surface for comv plementary engagement at 48 with the associated friction shoe generally designated 58.

One of the friction shoes 58 is shownV in detail in Figures 6 to 8 inclusive, said shoe comprising a main friction wall 52 frictionally engaged at 54 with the adjacent column-mounted wear plate 56 (Figures 1 and 2). Integrally formed with the main friction wall 52 of the friction shoe 58 are the spaced

triangular ledges

58 and 68 presenting on their lower surfaces crowned wedge faces for complementary engagement as at 48 with the inboard and

outboard bolster Walls

44 and 46 in the manner above described. Extending between the

ledges

58 and 68 is a rib 62 affording an abutment for a wedge face on the associated friction shoe actuator during assembly and disassembly of the side frame and bolster as hereinafter described. A lug 64 projects from the main friction Wall 52 beneath the rib 62, said lug being reinforced by the

spaced gussets

66, 66 and presenting a top crowned abutment surface 68 for engagement as at 18 with an equalizer, sometimes called a friction shoe actuator or pressure plate generally designated 12, said plate having the central opening 14 therethrough for the reception of a bolt 16, the head of which abuts the plate 12 as at 18 and is restrained against rotational movement with respect thereto by means of the inboard and outboard lugs 88 and 82 formed on the top of the plate 12.

A spring 84 is sleevedrover the bolt 16 and is seated at 86 against the bottom wall 26 of the bolster, the lower end of the spring being seated against a, spring plate 88 which is adjustably compressed against the spring 84 by means of ai nut 98.

On the top of the friction shoe actuator or pressure plate 12 adjacent opposite ends thereof are formed the

wedge surfaces

92, 92 slopingdownwardly toward the opening 14, said

wedge surfaces

92, 92 being adapted for cooperation with the

ribs

62, 62 of the

friction shoes

58, 58 during assembly of the truck. This is accomplished by driving a wedge between the plate 12 and the boss 94 formed on the top of the bottom wall 26 of the bolster', thus urging the plate 12 upward, whereby the Wedge

surfaces

92, 92 engage the

ribs

62, 62 of the respective friction shoes, thereby urging the latter inwardly into the

Dockets

34, 34 of the bolster. l

Under these conditions, it will be understood that the bolster may be entered at the top of the bolster opening 8 and may be lowered therein until suflicient clearance is afforded to permit entry of 4 the bolt 16. The wedge is then removed from between the boss 94 and the plate 12 and the bolt 'I6 is lowered into engagement with the plate 12 and the bolster. Thereafter the spring 84 is al plied to the lower end of the bolt and is adjusted to the desired compression'by means of the nut 98. The bolster is then elevated to the desired height within the bolster opening to permit assembly of the

bolster supporting springs

22, 22.

It will be understood that during a quick wheel change, the bolster may be elevated in the bolster opening and removed from the widened upper portion thereof after the

inboard springs

22, 22 have been removed from the side frame to afford clearance for the spring 84 and the lower end of the bolt 16, and it may be noted that after thc spring 84 has been compressed to urge the

friction shoes

58, 58 into engagement with the columns, the Ipressure on the shoes may be relieved by driving a wedge between the boss 94 and the plate 12, thus facilitating elevation of the bolster within the bolster opening.

As will be clearly understood from a consideration'of Figures 2 and 3, each side of the bolster is provided with the inboard andoutboard

column guide lugs

96 and 98 for cooperation with the inboard and outboard surfaces of the

columns

6, 6, thus affording an interlock .between the side frame and the bolster, the

outboard lugs

98, 98 being of less depth than the widened upper por- -tion I2 of the bolster opening to permit insertion of the bolster at the top of the bolster opening and the removal of the bolster therefrom during assembly and disassembly of the truck as heretofore described.

Referring now to the modification of `my invention illustrated in Figures 9 to 12 inclusive, the side frame generally designated |82 is substantially identical with that shown in Figures 1 anfl 2, said frame including the spaced columns |84, |84 and the intervening bolster opening |88 with the widened upper portion |88. Seated on the side frame |82 are the bolster supporting springs diagrammatically indicated at I I8, I I8 and affording support for the bolster generally designated II2, said bolster (being generally similar to that of the previous embodiment and comprising; at each side thereof a pocket I I4 for the reception of a friction shoe I I6, said shoe comprising a ledge I I8 at each side thereof incomplementary wedge engagement as at |28 `with the diagonal bolster wall |22 formed within the pocket I I4 at each of the inboard and outboard sides thereof. The rear extremity of the pocket is defined by the rear wall |24 having a central opening |26 therethrough for the reception of the friction shoe actuator or pressure plate |28.

The pressure plate or equalizer |28 isillustrated in detail in Figures 11 and 12 and comprises at opposite ends thereof the wedge surfaces |38, |38 converging downwardly toward the central opening |32 through the plate, the Wedge surfaces |38, |38 being in complementary engagement as at |34 with the lugs I 36, |38` formed on the friction shoes ||6, |I6. A spring |38 is seated on the top of the plate |28, the upper end of said spring being seated against a spring plate |48 which is adjustably compressed against the spring by means of a nut |42 threaded on the upper end of the bolt |44 which extends through the opening |32 in the plate |28 and is interlocked at its lower extremity at |46 with the bottom wall of the bolster.

Figure 10 illustrates the manner in which the friction shoes are retained within the pockets I I4,

I4 during assembly of the bolster and side frame, the pressure plate |28 having at opposite ends thereof the top wedge surfaces |48, |4'8 forv complementary engagement as at |50, |50 (Figure with the ribs |52, |52 on the friction shoes. The plate |28 is urged upwardly into wedge engagement with the shoes by means of an assembly wedge block |54 inserted between the plate 28 and a boss |56 formed on the bottom wall of the bolster. It will be understood that the friction shoes I I6, I6 in the arrangement illustrated in Figure 10 are urged inwardly into the bolster pockets, thus permitting the bolster and shoes to be inserted as a unit into the widened upper portion |08 of the bolster opening |06 and lowered onto the springs ||0, ||0. Thereafter, the wedge block |54 may be removed and the bolt |44 may be applied by means of a tool inserted between the outboard springs ||0, ||0. The spring |38 may then be placed in position and adjustably compressed by means of the nut |42. In the event that it is desired to elevate the bolster to remove one of the springs ||0, ||0, the nut |42 may be loosened or, if desired, a wedge may be inserted between the boss |56 and the plate |28.

It will be understood that the arrangement illustrated in Figures 9 and 10 is substantially identical with that illustrated in Figures 1 and 2 except for the fact that the actuating plate |28 is in wedge engagement with the shoes at |34, |34, and the spring l 38 is connected to the bolster and to the plate 28 in the reverse of the manner illustrated in Figures 1 and 2, whereby the nut |42 is disposed at the top of the bolster opening where it may be readily adjusted without disassembling the truck.

It is to be understood that I do not wish to be limited by the exact modifications of the dev ice shown which are merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. In a railway car truck, a side frame comprising tension and compression members and spaced columns defining therewith a bolster opening with a widened upper portion, a. spring group on said tension member in said bolster opening, a bolster supported by said group, said bolster having pockets in opposite sides thereof, each" pocket comprising spaced inboard and outboard wedge surfaces therein sloping toward the adjacent column, a friction shoe in each pocket engaging the Wedge surfaces therein and frictionally engaging the adjacent column, a plate member extending between the spaced-surfaces in each pocket and bearing against said shoes, said plate member being housed within the bolster, resilient-l means operatively associated with said bolster and said member for urging the latter into engagement with said shoes, and inboard and outboard lugs on said bolster cooperating with said columns to afford an interlock with said frame, the outboard lugs being of less depth than the widened upper portion of said bolster opening, whereby said bolster may be elevated therein and removed therefrom.

2. In a railway car truck, a side frame comprising tension and compression members and spaced columns defining therewith a bolster opening, a spring-group on said tension member in said opening, a bolster supported by said group, said bolster having pockets in opposite sides thereof, each pocket comprising spaced inboard and outboard wedge surfaces sloping downwardly toward the adjacent column, a friction shoe in each pocket engaging the spaced wedge surfaces therein and frictionally engaging the adjacent column, a plate member extending between the spaced surfaces in said pockets and bearing against said shoes, said plate member being housed within the bolster, resilient means compressed against the bottom wall of said bolster, and a bolt and nut assembly connected to the lower end of said resilient means and to said plate member for transmitting reaction of said resilient means thereto.

3. In a railway car truck, a side frame comprising tension and compression members and spacdicolumns defining therewith a bolster openingafgpring group on said tension member in said opening, a bolster supported by said group. said bolster having pockets in opposite sides thereof. each pocket comprising spaced inboard and outboard wedge surfaces sloping downwardly toward the adjacent column, a friction shoe in each pocket engaging the spaced wedge surfaces therein and frietionally engaging the adjacent column, a plate member extending between the spaced surfaces in said pockets and bearing against said shoes, said plate member being housed within the bolster, resilient means seated on the upper surface of said plate member, and a bolt and nut assembly connected to the upper end of said resilient means and to the bottom wall of said bolster.

4. In a railway car truck, a side frame comprising tension and compression members and spaced columns defining therewith a bolster opening, a spring group on said tension member in said opening, a bolster supported by said group, said bolster having pockets in opposite sides thereof, each pocket comprising spaced inboard and outboard wedge surfaces sloping downwardly toward the adjacent column, a friction shoe in each pocket engaging the spaced wedge surfaces therein and frictionally engaging the adjacent column, a plate member extending between the spaced surfaces in said pockets and bearing against said shoes, said plate member being housed within the bolster, and resilient means operatively associated with said bolster and said member for urging the latter into engagement with said shoes.

5. In a railway car truck, a side frame com-v prising spaced columns and an intervening bolster opening, resilient means on said frame in said opening, a bolster supported from said resilient means and comprising a top wall, said bolster comprising Wedge surfaces at opposite sides thereof sloping downwardly toward respective co1- umns, friction shoes in wedge engagement with respective of said surfaces and in frictional engagement with friction means on respective columns, an actuator housed within the bolster beneath said top wall-and extending transversely thereof, and resilient means independent of said first-mentioned resilient means for urging said actuator into engagement with said shoes, whereby the latter` are urged into engagement with said wedge surfaces and said friction means.

6. In a railway car truck, a side frame comprising spaced columns and an intervening bolster opening, resilient means on said frame in said opening, a bolster comprising a top wall and a bottom wall spaced therefrom, said bottom wall being supported from said resilient means, friction shoes in wedge engagement with wedge means on said bolster and in frictional engagement with friction means on said columns, an`

actuator housed within the'bolster between said walls and extending transversely thereof, resilient means under compression, and a bolt and nut assembly operatively connected to said lastmentioned resilient means and to said actuator fortransmitting reaction of said last-mentioned resilient means thereto.

7. In a railway car truck, a side frame comprising spaced columns and an intervening bolster opening, resilient means on said frame in said opening, a bolster supported on said resilient means and comprising top and bottom' Walls, friction shoes engaging wedge means on said bolster at opposite sides thereof, and an actuator' assembly partially housed within said bolster and operatively associated with said shoes for urging the same into engagement with said wedge means and with the associated columns, said assembly comprising a rigid member disposed between said walls, and resilient means bearing against said rigid member for urging it into engagement with said shoes.

8. In a railway car truck, a side frame comprising spaced columns and an intervening 'bol` ster opening, resilient means on said frame in said opening, a bolster supported from said resilient means and comprising a top wall, friction shoes in wedge engagement with wedge means on said bolster and in frictional engagement with friction means on said columns, an actuator housed within the bolster and extending transversely thereof andunderlying said top wall, and resilient means for urging said actuator into engagemcnt with said shoes, whereby'the latter are urged into engagement with said wedge and friction means.

9. In a railway car truck, a side frame comprising spaced columns and an intervening bol`- ster opening, a spring group on said frame in said opening, a bolster member supported on said group and comprising a top wall, friction shoes in wedge engagement with said bolster and in frictional engagement with respective columns, 'a pressure member housed in said bolster, extending transversely thereof beneath said wall, and bearing against said shoes, resilient means under compression seated against one of said members, and a'bolt and nut assembly connected to said resilient means and to the other of said members.

10. In a railway car truck, a side frame comprising sr aced columns and an intervening bolster opening, resilient means on said frame in said opening, a bolster supported on said resilient means, friction shoes engaging wedge means on said bolster at opposite sides thereof, and an actuator assembly partially housed within said bolster and operatively associated with said shoes for urging the same into engagement with said wedge means and with the associated columns, said assembly comprising a at rigid member housed within the bolster and bearing at each end thereof against abutment means on the shoe associated with one column,'said abutment means ing an abutment face on its upper surface., all of said faces being crowned.

12. Inv a friction shoe actuator member for a railway car truck, a plate having means centrally thereof for connection to an associated element, abutment means on one side of said plate for cooperation undercertain conditions with associated friction shoes, and wedge faces on the other side of said plate converging toward said firstnmentioned means* and formed and arranged for coqperation under other conditions with said shoes.

13. In a friction shoe, a member having a main friction wall, spaced ledges projecting from one side of said wall and presenting wedge faces diagonal with respect thereto, an abutment rib extending between said ledges and spaced from said wall, and a lug projecting from said side of said wall beneath the level of said rib, said lug having a-top surface formed and arranged for abutment with an associated actuator.

14. In a railway car truck, a side frame comprising spaced columns and an intervening bolster opening, a box-section bolster resiliently supported from said frame in said opening, wedge means at opposite sides of said bolster, friction shoes engaging respective wedge means and frictionally engaging adjacent columns, and means urging said shoes into engagement with said wedge means and columns comprising an equalizer disposed between the topand bottom walls of said bolster and engaging abutment means on said shoes.

15. A friction shoe and bolster assembly comprising a box-section bolster with pockets in opposite sides thereof and wedge surfaces in said pockets, friction shoes engaging respective surfaces, and means for maintaining said shoes within said pockets comprising a rigid member housed between the top and bottom walls of the bolster and having wedge surfaces engaging abutment surfaces of said shoes.

16. A friction shoe and bolster assembly comprising a bolster with pockets in opposite sides thereof, wedge surfaces on said bolster within said pockets, friction shoes in said pockets engaging respective surfaces, and means for maintaining said shoes within said pockets comprising a member housed within the bolster and-bearing against respective shoes and a wedge block wedged between said member and a wall of said bolster.

17. In a railway car truck, a side frame member, a bolster memberl spring-supported therefrom, a portion-of one of said members extending between spaced friction surfaces of the other member, friction shoes engaging wedge means on said portion and frictionally engaging respective surfaces, actuating means for said shoes comprising a member` housed within said portion and engaged with said shoes, and resilient means carried by said portion for urging said last-mentioned member into engagement with said shoes.

18. In a, railway car truck, a side frame comprising spaced columns, a box-section bolster spring-supported from said frame between said columns, friction shoes engaging respective columns 4and wedge means on said bolster, actuating means for said shoes comprising a member housed between the top and bottom walls of the bolster in engagement with said shoes, and resilient means operatively connected to said member for urging the same into said engagement.

19. In a railway car truck, a side frame comprising spaced columns, a bolster spring-supported therebetween, friction shoes engaging respective columns and engaging Wedge means movable with said bolster, actuating means for said shoes comprising spaced spring abutment members, one 'of which is anchored to the bolster and the other of which is engaged with said shoes,

and resilient means compressed between said members for urging said other member into engagement with said shoes.

20. In a railway car truck, a side frame comprising spaced columns, a bolster spring-supported therebetween, friction shoes engaging respective columns and engaging wedge means movable with said bolster, actuating means for said shoes comprising spaced spring abutment members, one of which is anchored to the bolster and the other of which is engaged with said shoes, and resilient means compressed between said members for urging said other member into engagement with said shoes, said other member being housed within the bolster and being partially housed within each shoe.

21. In a railway car truck, a side frame comprising spaced columns. a box-section bolster spring-supported therebetween and comprising top and bottom walls, friction shoes engaging respective columns, wedge means vertically movable with said bolster and in complementary wedge engagement with said shoes, actuating means for said shoes comprising spaced interconnected abutment members, one of which is disposed between said walls in engagement with said shoes, and resilient means compressed between one of said walls and the other of said members for urging the first-mentioned member into engagement with said shoes.

22. In a railway car truck, a side frame comprising spaced columns, a box-section bolster 'spring-supported therebetween and comprising top and bottom walls, friction shoes engaging respective columns, wedge means vertically movable with said bolster and in complementary wedge engagement with said shoes, and actuating means for said shoes comprising spaced interconnected abutment members, one of which is disposed between said walls in engagement with said shoes. and resilient means compressed between one of said walls and the other of said members for urging the first-mentioned member into engagement with said shoes, said first-mentioned member being housed at each end thereof within one of said shoes.

23. In a railway car truck, a side frame member, a bolster member spring-supported therefrom, vone of said members having a portion extending between spaced friction surfaces on the other of said members, said portion having wedge means adjacent respective surfaces, friction shoes each cooperating with one of said surfaces and the adjacent wedge means, and actuating means for said shoes comprising spaced plates, one of which is anchored to said portion and the other of which engages said shoes, and resilient means compressed between said plates for urging said other plate into engagement with said shoes.

24. In a railway car truck, a. side frame member, a bolster member spring-supported therefrom, one of said members having a portion extending between spaced friction surfaces on the other of said members, said portion having top and bottom walls and wedge means adjacent respective surfaces, friction shoes each cooperating with one of said surfaces and the'adjacent wedge means, and actuating means for said shoes comprising a pair of spaced interconnected plates,

one of which engages abutment means on said shoes at a point between said walls, and resilient means compressed between the other plate and a wall of said bolster for urging the first-mentioned plate against said abutment means.

25. In a railway car truck, a side .frame member, a bolster member spring-supported therefrom, one of said members having a portion extending between spaced friction surfaces on the other of said members, said portion having wedge means adjacent respective surfaces, friction shoes each cooperating with one of said surfaces and the adjacent wedge means, and actuating means for said shoes comprising-'a pair of spaced interconnected plates, one of which engages abutment means on said shoes, and resilient means compressed between the other plate and a wall of said -bolster for urging thefirst-mentioned plate against said abutment means, said first-mentioned plate having its ends housed within said shoes and being housed for its entire length within said portion.

26. In a railway car truck, a side frame comprising spaced columns and an intervening bolster opening, a box-section bolster resiliently supported from said frame in said opening, wedge means at opposite sides of said bolster, friction shoes engaging respective wedge means and frictionally engaging adjacent columns, and means urging said shoes into engagement with said wedge means and columns comprising an equalizer disposed between the top and bottom walls of said bolster and engaging abutment means on said shoes, said equalizer transmitting vertical forces lfrom said bolster to said shoes.

27. In a railway car truck, a side frame comprising spaced columns and an intervening bolster opening, a box-section bolster resiligntly supported from said frame in said opening, wedge means at opposite sides of said bolster, friction shoes enga-ging respective wedge means and frictionally engaging adjacent columns, and means urging said shoes into engagement with said wedge means and columns comprising an equalizer resiliently mounted in said bolster and bearing upon4 REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,053,991 Goodwin Sept. 8. 1936 2,118,006 Couch May 17, 1938 2,257,109 Davidson Sept. 30, 1941 2,306,395 Cottrell Dec. 29, 1942- 2,346.860 Mohl Apr. 18, 1944 2,362,989 Cottrell Nov. 21, 1944 2,392,597 Lehrman Jan. 8, 1946 2,392,599 Light Jan. 8, 1946