CA1065190A - Articulated trucks - Google Patents

Abstract

Abstract of the Disclosure A vehicle running gear with articulated, self-aligning, wheelsets having means providing elastic restraint of steering moments. This means ensures that the axles of the wheelsets, while free to yaw conjointly to assume a radial position in curves, are restrained from unstable steering motions when operating in a relatively straight line at high speeds. The wheelset bearings are each carried by a subtruck which is shaped to provide a steering arm, and these arms are movably coupled in a region intermediate the axles, to accommodate conjoint yawing motions of the axles with respect to each other and in the general plane of the axles, Particular attention is given to the importance of "yaw" and "lateral" restraints, between the two wheelsets of a truck and, in each of the disclosed embodiments, resilient means of predetermined stiffness is constructed and disposed to oppose de-parture of the arms from a position in which the wheelsets are parallel, while other resilient means reacts between the steering arms, in the region of their coupling, and opposes differential yawing, or lateral motion of the axles, across the line of general vehicle motion. Elastomeric pads or blocks are disclosed as providing the damping and, in some disclosed arrangements, the degree of restraint of the movements of one axle differs from the degree of restraint of another axle. In accordance with one disclosed feature, coupling is also provided between one steering arm and the vehicle body, to control yawing between the wheelsets and the body. According to another portion of the disclosure, brake improvements, for a railway vehicle, reduce brake shoe wear, and eliminate contact between the brake shoes and the wheel flanges.

Description

While of broader applicability, for example in the field of highway vehicles where use of certain features of the invention can retuce lateral scrubbing of tires as well as lessening the width of the roadway required for negotiating curves, this invention is especially useful in railway vehicles and particularly rail~ay trucks having a plurality of axles. Accordingly, and for exemplary purposes, the invention will be illustrated and described with specific reference to railway rolling stock.
The axles of the railway trucks now in normal use remain sub-stantially prallel at all times tviewet in plan). A ~ost important consequence of this is that the leading axle can not assume a position radial to a curved track, and the flanges of the wheels strike the curved rails at an angle, causing objectionable noise and excessive wear of both flan~es and rails.
Much consideratio~ has been given to the avoidance of thisprobl~m notably the longstanding use of wheels the treads of which have a conical profile. This expedien~ has assisted the vehisle truck to negotiate very gradual curves.

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llowcver, ~s economic factors h~ve le~ the railroads to accept hi~her wheel loads and operating speeds, the rate of wlleel an~ rail wear becomes a major problem. A second serious limitation on performance and maintenance is the result of cxcessive, and even violent, oscillation of the trucks at high s~eed on straight tràck. In such "nosing", or "hunting", of the truck the wheelsets bounce back and forth between the rails. A~ove a critical speed hunting will be initiated by any track irregularity. Once started, ~O the hunting action will often persist for miles with flange impact, excessive roughness, wear and noise, even if the speed be reduced substantially b~low the critical value.

In recent ef~orts to overcome this curving problem, yaw fle~ibility has been introduced into the design of some trucks, and arrangements have even been proposed which allow wheel axles of a truck to swing and thus to become positioned substantially radially of a curved track. I~ow-ever~ such efforts have not met with any real success, primarily because of lack of recognition of the importance c of providing the required lateral restraint, as well as yaw flexibility, between the two wheelsets of a truck, to prevent high speed hunting.

For the purposes of this invention, yaw stiffness can be defined as the restraint of angular motion of wheel-sets in tlle steering direction, and more particularly to the restraint of conjoint yawing of a coupled pair of wheel-sets in a truc~. The ~'lateral" stiffness is defined as the restrain~ of the motion of a wheelset in the direction of i~s general axis of rotation, that is, across the line ~D of general motion of the vehicle. In the apparatus of the inVeIltiOn, such lateral stifness also acts as restraint on Sl90 differelltial yawing, of a coupled pair of wheelsets.

The above-mentioncd general problcms produce many particular difficulties all of which contribute to excessive cost of operation. For example, there is deterioration of the rail, as well as widening of the gauge in curved track.
In straight track the hunting, or nosing, of the trucks causes high dynamic loading of the trac~ fasteners, and of the press fit of the wheels on the axles, with resultant loosening and risk of failure. A corresponding increased cost of maintenance of both trucks and cars also occurs.
As to trucks, mention may be made, by way of example, to flange wear and high wear rates of the bolster and of the surfaces of the side framing and its bearing adapters.

As to cars, there occurs excessive center plate wear, as well as structural fatigue and heightened risk of derailment resulting from excessive flange forces. The effects on power requirements and operating costs, which result from wear problems of the kinds mentioned above, will be evident to one skilled in this art.

2D In brief, the lack of recognition of the part played by yaw and lateral stiffness has led to: ~a) flange contact in nearly all curves; (b)~ high flange forces when flange contact occurs; and (c) excessive difficulty with lateral oscillation at high speed. The wear and cost problems which result from Eailure to pro-vide proper values of yaw and lateral stiffness, and to control such values, will now be understood.

SUM~ARY OF TIIE INVENTION

It is thc gcneral objective of my invcntioll to overcome such problcms, and to this cnd I utilize an ~ nti5~
articulated truck having novelly positioned elastic restraint ~eans which makes it possible to achieve flange-free opera-tion in gradual curves, low flange forces in sharp curves, and good high speed stability.

I have further discovered that application of certain principles of this invention to highway vehicles not only reduces tire scrubbing and highway space require-ments, as noted above, but also promotes good stability at high speed.

According to one aspect of the invention, a rail-way vehicle truck assembly comprises main truck framing, first means movably associating said framing in load-bear-ing rela~ion with the railway vehicle, a pair of subtrucks each movably coupled to said main truck framing and each carrying an axle-borne wheelset, each said subtruck having a portion extending from its associated wheelset to a common region substantially midway between the two axles, means in said region resiliently coupling said subtrucks to one another, independently of yaw-inducing connection with said framing, for conjoint steering motions and consequent posi-tioning of their axles radially of a curved track, and resil-ient means interposed between spaced portions of at least one subtruck and said main truck framing, said resilient means being arranged to oppose departure of said subtrucks from a position in which the wheelsets are parallel.

In accordance with another aspect of the inven-tion, in a vehicle having at least one pair of axle-borne wheelsets the axles of which are longitudinall~ spaced from the center of the vehicle in generally parallel adjacency and lie in a plane within which said axles may yaw, appara-tus for mounting said wheelsets upon said vehicle including mechanism for transmitting load from the vehicle to the ~wheelsets and providing for relative pivotal, yawing, move-rnents of the axles in said plane, as the wheels roll on a running surface, the apparatus for mounting the wheel-sets comprises a pair of frame structures, each coupled to an associated one of said axles in such manner that each axle has a substantially fixed angularity with respect to its frame structure in said plane, each frame structure having a portion extending from its associated axle to a common region substantially midway between said two axles;
means coupling said frame structures directly to one another in said region, and independently of said load transmitting mechanism, for relative yawing movement, and with predeter-mined stiffness against motions in the general direction of axle extension; a pair of side frame members each extend-ing to and spanning a pair of adjacent end portions of the two axles, said frame members being free for relative tilt-ing movements in said plane; means forming connections coupl-ing each end portion of each axle, and its frame structure, to the adjacent side frame member, the connections coupl-ing the ends of that axle which is more remote from the ~5 center of said vehicle, with the adjacent side frame mem-bers, including means providing elastic restraint of pre-determined stiffness against yawing movements of the latter axle; and means coupling each side frame member to said vehicle and including other elastic restraint means pro-viding predetermined yaw stiffness between said frame mem-bers and the vehicle.

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3t) In accordance with still another aspect of the :invention, in a railway vehicle truck, having main framing and a pair of axle-borne wheelsets each carried by a steer-:ing arm which has spaced portions journalling its associated wheelset, and which steering arms have means pivotally con-necting them directly to one another, in a region substan-tially midway between said two axles, and accommodating positioning of the axles radially of a curved track, to insure that steering moments are freely exchanged between said wheelsets, means for minimizing wheel-flange-to-rail contact, and for maximizing high speed stability, the means connecting the steering arms comprises first elastomeric means proportioned and disposed to provide each wheelset with a predetermined value of yaw stiffness with respect to the main framing; second elastomeric means proportioned and disposed to provide a predetermined value of yaw stiff-ness between the main framing and the vehicle body; and third elastomeric means proportioned and disposed to resist differential displacement of said steering arms while permit-ting exchange of such steering moments between the wheelsetsand thereby permit each axle to assume a position radial of a curved track, said third elastomeric means being located in the region of said means pivotally connecting the steer-ing arms to one another and reacting between said steering arms.

With particular reference to railway trucks, the truck is so constructed that: ~a) each a~le has its own, frequently indivi~ual, value of yaw stiffness with respect -5b--f``~

51~0 to the truck framing; ~b) such lateral stiffness is pro-vided as to ensure the exchangin~ of steering moments prop-erly between the axles and also with the vehicle body; and (c) the proper value of yaw stiffness is provided between the truck and the vehicle.

An embodiment representative of the invention has been tested at nearly eighty miles per hour, with vir-tually no trace of instability. With another embodiment, radial curving has been observed at less than 50 foot radius, and flange-free operation is readily achieved with all em-bodiments on curves of at least 4 degrees.

With more particularity, the yawing motion of the axles is flexibly restrained by the provision of re-straining means of predetermined value between the side frames and the steering arms of a truck having a pair of subtrucks coupled through steering arms rigidly supporting the axles. Elastomeric means for this purpose is -5c ~,~

provided between the axles and the adjacent side frames, preferably in the region of the bearing means. ~uch means may be provided at one or both axles o~ the truck. If pro-vided at both axles, it may have either more or less re-straint at one axle, as compared with the restraint at theother, depending upon the requirements of the particular truck design.

Elastomeric restraining means is provided in the region of the coupling between the arms to damp lateral axle motions, which results in so-called "differential"
yawing of a coupled pair of subtrucks.

~ tow bar arrangement is used to take care of longitudinal forces between the car body and the flexibly mounted wheelsets. This arrangement has several advantages, discussed hereinafter, one of which is to prevent exces-sive deflections, in the elastomeric pads which mount the steering arms to the side frames and the side frames to the car body.

A special sliding bearing surface is provided between the truck side frames and the car body, further to limit the flange forces in very sharp curves.

Brake improvements are provided and when used in conjunction with articulated trucks of the kind herein disclosed, the contact of the brake shoes with the wheel flanges is virtually eli~inatea. With prior arrangements, such contact has resulted in substantial wear and in uneven braking.

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BRI}~F DESCRI~'TION O~ THF. DRI~WINGS

Several embodiments representative of my inven-tion are illustrated.

In the drawings:

Pigure 1 is a schematic showing of a first embodiment of the invention, and illustrating a railway vehicle having truck means which includes a pair of wheelsets coupled and damped in accordance with principles of the invention;

Figure 2 shows schematically, and in basic terms, the response of such a truck to a curve;

Figure 3 shows a plot of the reaction of the flange force between the truck side frames and the vehicle, using modified restraining means and under conditions of ve-ry sharp curving, the reaction being plotted against the angle of track curvature;

Figure 4 is a force diagram analyzing the response o a truck generally similar to that shown in Figure 1, and including in addition a stee~ing link or tow bar;

Figure S is a plan view of a railway truck con-structed in accordance with the invention, and embodying principles illustrated schematically in Figures 1 and 4;

Figure 6 is a side elevational ~iew of the apparatus shown in Figure 5;

: Figure 7 is a plan view of the railway truc~ of ~Figures 5 and 6 with certain upper parts omitted, in order more clearly to show the steering arms, their central connection, and features of brake rigging;

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I`i~ure S is a side elevational view of the a~paratus sl~own in l:i~urc 7;

Fi~ure 8a is a force polygon illustrating th~ function-ing of the brakes;

Figure 9 is a cross-sectional view taken on the line 9-9 of Figure 6;

Figure 10 is an enlarged cross-sectional view of the journal box structure taken on the line 10-10 of Figure 6;

Fi~ure 11 is an enlarged sectional view of the central ,o connection of the steering arms taken on the line 11-11 of Figure 7;

Figure 12 is a cross section taken on the line lZ-12 of Figure 11;

Figure 13 is a plan view illustrating a modified form of railway truck embodying the invention which uses side frame and bolster castings similar to those used in conventional freight car trucks;

Figure 14 is a side elevational view of the apparatus of Figure 13;
r ~ igure 15 is an enlarged sectional plan view of the central connection device of the steering arms of the truck of Figures 13 and 14;

Figure 16 is a plan view of another modified form of truck, similar to Figure 5, but having inboard ~earings;

Figure 17 is a fragmentary plan viel~ of a modification illustrating latcral stops for the side frames of a truck of the general kind shown in Figures 5-10; and S~
~ igure 18 is a fra~mentary cnd view of the apl~aratus o~ ~igure 17.

D~SCRIPTION OF REPRESEINTATIVE EMBODIM~NTS

The steering features of a first embodiment for a four wheel railroad car truck are illustrated somewhat schematically in Figures 1 and 2. The embodiment for use under the trailin~ en~ of a highway vehicle would be vir-tually identical, but, for simplicity, railroad truck ter-minology is used in the description.

The essential parameters are as follows:
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The yaw (longitudinal) stiffness between the "inside" axle "B" and the truck side frames "T" is very high, i.e. a pinned connection.

The yaw stiffness between the "end" axle "A" and the truck side frames "T" is ka.
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The yaw stiffness between the truck side frames "T" and the vehicle is k .

The side frames "T" are essentially independent being free to align themselves over the bearings ~not . ~O illustrated) of axles "A" and "B", even when there is sub-. stantial deflection in the longitudinal direction of the resilient member ka.

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Lateral forces between the two axles are exchanged at point "P", located in the mid-region between a.pair of : subtrucks, or steering arms, A' and B'. This interconnec-tion has a lateral stiffness of kl and may also make a contribution to the yaw stiffness bctween the two axlcs.
This connection provides for balancin~ of stccrin~ momcnts ~ 9 . . .

bct~een tlle two a~le5 ~ as w~ll as providing the lateral stiffll~s~s .

The basic response of such a truck to a curve is shown in Figure 2. The elastic restraints ka and ke haYe been deflected by lateral forces "F". The forces "F" can arise either from flange contact or from steering moments caused by creep forces between the wheels and the rails.
Experimentally it has been observed that for relatively low values of ka and ke, the axles will tend to assume a radial D position in curvcs for a large range of variation of the ratio ~. I have further discovered that for higher values, the proper value for this ratio must be chosen as a function of the truck wheelbase "w" and the distance s from axle "B"
to the vehicle center. Thus a means is provided to have the high value for yaw stiffness needed for high speed stability while simultaneously providing radial positioning of the axles in sharp curves. The basic mathematical relation-ships which assure radial positioning of the axles are as follows:

For the axles to be in a radial position, their .20 angular displacement will be proportioned to their distance from the center of the car body;

~A ~ ~B = c x w and ~B = c x s , where c ~ the curvature per foot of length along the curve.

This gives the following ratio between the angles and the distances.
~A ~ ~B = w The angles are also dependen~ on the yaw stiffness.

~A - ~B ~ ~ x w!2 and ~B = F x w ka x d ke X-10 .

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Substituting, we find tllat thc relationship between theyaw stiffnesses and the ~istance should be;

ke ~ ka x 2w , or ka - s S ke 2w Given the proportionality ka = s it is a simple matter to translate the values for elastic restraint into suitable components. In the desi~n and testing of one of the truck embodiments described below, the value for ka was selected to obtain stability against hunting up to a car speed of one hundred miles per hour. With this com-/D ponent established, use of the pro~ortionality consideredabove readily yields the values to be embodied in the other elastomeric restraints, which are disposed between the car body and side frame ~ke~.

In the case of rail vehicles where there is only a small clearance between the wheel flanges and the rail, the above ratio should be closely maintained. The action of the orces arising from the sel steering moments of the wheelsets will correct for some error, and the curving behavior will be superior to a conventional truck, even if it is not perfect.

In the case of highway vehicles, when a low value of ka is chosen, the rear bogie will tend to follow the front end o~ the vehicle rather precisely in a curve. As ka is increased, the trailing end of the vehicle will track inside ~he front end. If ka is made very stiff, the bogie will approach, but always be superior to, the tracking characteristics of a conventional bogie. As will be under-stood, given ka~ ke can be calculated.

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l~']lilc thc cmbo~iment shown in Figures 1 and 2 ~ill provi~e thc ~csired major improvement in curving bellavior and high spee~ stability on all ordinary railroad curves, there is also a need to limit the flange force "F"
which occurs when operating ocCasionally on very sharp curves. This is most easily done by making ke a non-linear elastic reStraint as shown in Figure 3.

This restraint is comprised of a steep linear center section where ke ~ ka x 2w and end sections where o the value is much less. This will limit the reaction force "R" between the truck sideframes and the vehicle, which will in turn limit the flangb force "F".

For certain applications such as rail rapid transit vehicles where there is a need to obtain the lowest possible flangwear and operating noise on sharp curves, and at the same time obtain good high speed stability, it will be found desirable to add the feature shown in Figure 4. The addition of steering link, or tow bar, "L" provides a means to keep the yaw stiffness high on straight track without contributing significantly to the flange force in curves.
The presence of the restraints kt make it possible to choose low values for ~a and ke without sacrificing yaw stif~ness between the vehicle and the running-gear and within the running-gear.

The following parameters are dealt with in con-sideration of Figure 4:
s = distance from vehicle center to closest axle;
w - truck wheelbase, axle-to-axle;
b = center line of subtruck (steering arm) associated with 3D axle B;
a = center line of subtruck (steering arm) associate~ with axle A;
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c - center linc of truck fr~ling;
O = ccnter (pivot point) of truck framing, P = point of interconncction of the subtrucks;
L = tow bar (steering link). In Figure 4 it is shown offset from the vehicle centerline better to show kt;
M ~ the point of interconnection between the tow bar and subtruck a;
x = the distance between the truck center O and the inter-connection at M; ~ kt = the lateral flexibility which limits the ability of the steering link to keep the lateral position of M
the same as the lateral position of P;
[When certain prototype trucks were operated in the Figure 4 configuration, kt was the lateral stiffness of pads used to provide ka between the side frames and the subtrucks.]
y = the distance between the connection of the steering link to the truck framing at ~I, and the point of connection of the link to the vellicle; and 2~ f = the distance between the truck centerline and point M
at the distance x from the truck center. This dimen-sion is used in deriving the computation of the proper dimension for x. r The optimum values for x and kt must be found by experiment. However, it can be shown that x should be larger than a specific mi~imum at which the axles would assume a radial position if the restrain~s kt were infini-tely rigid. This minimum ~alue can be calculated using the equation xn~in = ~2 . This valuc is based on 4 (s + w~
30 the fact that thc anglc bctween "h;' ~ L to axlc B, Figs.
1 and 2) and the vehiclc centeT line,and the angle bctwecn 13.

"a" ~ L to axle A, Figs. 1 and 2,) and the vehicle center^
line arc proportional to the.distanccs from the center of tlle vellicle (w and s + w). The latcral distance "f" in Figure 4 can be calculated two ways, i.e.:

(1) f = - ( 2s + w ) x and;

t2) f r t w - x ) w where r is the track curvature.

Equating these two expressions;

2sx ~ wx ~ ( w - x ) w o Solving for x gives; -x 4 (w ~-w)-; -The optimum value for kt will depend primarilyon the total value for yaw stiffness required for h'igh speed stability, the percentage of that valuc supplied by ka and ke~ and the percentage of that value contributed by the rotational stiffness of the connection at P. The value kt can be chosen to make up the ~emainder required.

There is also the ques,tion o~ choosing a proper value for y. This should in general be chosen as long as practical, if it is desired to minimize coupling between 20 the lateral motion of the vehicle with respect to the running-gear and ~he steering motions of the axles. However the length y has been made as short as two thirds w with success in prototypes,.there being-some indication in test-ing that a certain amount of coupling between lateral motion of the car,body, with respect to the tTuck, and the steer-ing action of the truck helps to stabilize lateral motions of the car body.

The principles disclosed above can be used dircctly ~ 14.

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to dcsigll running-gcar haYing an evcn number of ~xles by grouping thc1n in pairs. These principles have also been used to desigJI a three-axle bogie.

The principles considered above have been applied in the design of a number of s~ecific trucks, particularly railway freight trucks. By way of example, three such embodiments arc shown. One appears in ~igures 5 to 12, another in Figures 13 to lS, and the third in Figure 16.
Detail modifications are shown in Figures 17 and-18.

~ Yith detailed reference, initially, to Figures 7 and 8, from which part~ have been omitted more clearly to show the manner in which each of two axles 10 and 11 is rigidly supported by its subframe (termed a "steering arm" in the following description), it will be seen that each axle is carried by its steering arm, 12 and 13, respect-ively, ~nd that each axle has a substantially fixed angularity with respect to its steering arm, in the general plane of the pair of axles. The steering arms are gen-erally C-shaped, as ~iewed in plan, (c.f. the steering arms A' and B' o~ Figures 1 and 2), and each has a portion extending from its associated axle to a common region (12a, 13a) substantially midw~y between the two axles.
Means bearing the general designation 14, to which more detailed refcrence is made below, couples the steering arms 12 and 13 with freedom for relative pivotal movement and with predetermîned stiffness against lateral motion in the general direction of axle extension. In this embodiment the stiffness against lateral motion, in the direction of axle extension and in the plane of the axles.(it corres-ponds ~o the rcsilient means Kl sllown diagrammatically at P in Fi~ure 1), takes ~hc form of a tubular block 15 of any 1'3~

suitable elastomeric material, e. g. rubber. It is suit-ably bonded to a ferrule, or bushing 16 (see particularly Figures 11 and 12), which is provided as an extension of steering arm 13, and to a bolt 17 which couples the steer-ing arms, as is evident. This block or pad 15, throughwhich the steering moments are exchanged, has considerable lateral stiffness. The resilience is sufficient so that each axle is free to assume a position radial of a curved track, and sufficient to allow a slight parallel yaw motion of the axles. This acts to prevent flange contact on straight track when there are lateral loads such as strong cross winds.

Turning now to the manner in which each axle is carried by its associated arm, it is seen that each steer-ing arm carries, at each ~f its free ends, journal box struc-ture 18 integral with the arm (see for example arm 12 inFigures 17 and 18). The box shape can readily be seen from the figures and opens downwardly to receive bearing adaptor structure 19, of known type, which locates the bear cartridge 20. Both ends of both axles 10 and 11 are mounted in this fashion, which does not require more detailed description herein. Retaining bolts 21 prevent the bearing 20 from falling out of the adapter 19 when the car truck is lifted by the truck framing.

Each journal box 18 has spaced flanges 22,22 which have portions extending upwardly and laterally of the journal box. These flanges serve as retaining means for the car side frames, and also for novel pads interposed between the journal boxes and the side frames, as will presently be des-cribed. However, before proceeding with ~n~ o that dcscription, and still witll reference to Figures 7 and 8, it will be noted that each steering arm 12 and 13 carries a novel bra~e and bra~e beam assembly. These assemblies are designated, generally, at 23 ~Figure 8) and each includes a braced brakc beam 24, extending transversely between the wheels (e.g. the wheels 25,25 ca-rried by axle 10), and each end of each beam carries a brake shoe 26 which is aligned with and disposed for contact with the confronting tread of the wheel. The mounting of the brake assemblies is charac-teristic of this invention - in which each axle is fixed as against swinging movements with respect to its associated steering arm - and has significant advantages considered later in this descriptinn. For present purposes it is sufficient to point out that the brake beams 24 are pre vented from moving laterally toward and away from the ~langes 25a of the wheels, and for this purpose the opposite end portions of the beams are carried by rod-like hangers 27, ~ach of which extends through and is secured in a sloped pad 28 provided in corner portions of each steering arm 12 and 13 (see particularly Figure 8).

In particular accordance with my invention, and with reference to ~igures S and 6, reference is now made to tlie manner in which the truck side frames 29,29 are carried by the steering armsj being supported upon elas-tomeric means which flexibly restrains conjoint yawing mo~ions of the coupled pair of wheelsets, that is provides restraint of the steering motions of the axles with respect to each other, and thus opposes departure of the subtrucks (the steerin~ arnls and thcir a~lcs) from a pOSitiOJl in which the wheelsets are parallel~ As will now be under-s~ood from Figures 2 and 3, described above, this restrain-ing means (ka in those figures) may be provided only at t~
thc cnds of that axle w}lich is n-ore.remote from the ccnter of the vehicle. Ilowevcr, it is frequently ~esirable to provide SUCll restraint at the en~s of each axle. Accord-ingly, Figures 5 and 8 show restraint at each axle; it can be of different value at each, depending upon tlle part-icular truck design.

As shown in Figures S to 8, the restraining means takes the form of elastomeric pads 30, preferably of rubber, supported upon the journal box, between the flanges 22, and interposed between the upwardly presented, flat, surface 18a of each journal box 18 and the confronting lower sur-face 31 (Figure 10) of the I-beam structure which comprises the outboard end portions 32 of each side frame 29. As indicated in Figures 7 and 8, and as shown to best advan-tage in Figure 10, the pads 30 are sandwiched between thin stecl plates .~.0~, 30a, the upper of which carries a dowel 33 and the lower of which is provided with a pair of dowels 34. The upper and lower dowels are received within suit-able apertures provided, respectively, within the surface ~o 31 of side frame end portion 32, and the confronting sur-face 18a of journal box 18. The purpose of the dowels is to locate the elastomeric pads 30 with respect to the jour-nal box, and to position the side frame with respect to the pad 30. The side frame is thus supported upon the pads and between the flanges 22.

~ As shown in Figure 6, each side frame 29 has a ~ center porti~n which is lower (when viewed in si~e eleva-; tion) ~han its end portions 32. This center portion includes part of .a web 35 having a tvp, laterally extending, flange 36 wllich is narrower at its outer extremities (Figure 5) which overlie the journal box 18, and provides the bcaIing 18.

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surface 31 ~igure 10). The flange 36 reaches its maximum width in a flat central section 37 which c~mprises a seat for supporting an elastomeric spring member 38. This member has the form, prior to imposition of the load, of a rubber sphere. Member 38, although not so shown in the drawings, may if desired be sandwiched between steel wear p~ates.
Desirably, and as shown, means is provided for locating the member 38 with respect to the seat 37 of the side frame, and with respect to the overlying car bolster 39 (Figures 6 and 9), which, with sill ~0, spans the width of the car and is secured thereto. The car is illustrated fragmentarily at 41, in Figure 6. This locating means, as shown in Figures 5, 6 and 9, may ~onveniently take the form of lugs 42 integral with the support surface 37 and the confronting lower surface of car bolster 39. A bearing pad 43, which may be of poly-tetrafluoroethylene, available on the market under the trade-mark "Telfon", is interposed between the upper surface of car bolster 30 and the overl~ing car sill structure 40 (Figures 6 and 9)~ This forms a sliding bearing surface, which operates to place a limit on flange forces which might otherwise become excessive in very sharp curves.

As will be understood, the resilience of the elasto-meric shpere-like members 39 provides the restraint identified as ke in the description with reference to Figures 1 and . 25 2. As stated, its value is determined in accordance with the proportionality ka = s In one embodiment of the invention :~ ke ~w : which yielded good results, sphere-like springs marketed by Lord Corporation, of Erie, Pennsylvania, and identified by part number J-13597-1, were found suitable for applicant's special purposes described above.

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Thc truc~.shown in ~-igures 5 - 8 can be made to function as does the truck of ~igures 1 and 2 by either omitting pads 30' at axle ll,`or ~y ma~ing these pa~s substantially stiffer than pads 30 at axle 10. The bene-fit acllieved by doing this is that the steering effect of a lin~age L, such as shown in Figure 4, is obtained merely by the pro~ler distribution of the stiffness of pads at the axles.

A support, or cross-tie, 44 extends between ~he o webs 35 of the side frames 29, in the central portion of the latter (Figures 5 and 6), and has its ends fastened to the side frame web as shown at 45 in Figure 9. The cross-tie is a relatively thin plate with its height ex-tending vertically, and its centçr portion has an aperture 46 through which passes the means 14 which couples the mid-portions o~ the two steering arms 12 and 13. It is important for the purposes of the invention that there be freedom for limited tilting of one side frame with respect to the other, in the general plane containing the axles ~O 10 and 11. (See also the ~lexible side frames T of the apparatus shown schematically in Figures 2 and 3.) In the present embodiment this freedom is ensurcd by limiting the thickness of the cross-tie 44 to a value such as to permit the required flexibility between side rames.

A p~ir of strut-like dampers 47,47 interconnect ~he side frames and the.car bolster 39. I~hile these dam-pers have been omitted from Figures S and 6, in the inter-est of clarity of illus~ration, they show to good advan-tage in Figure 9. Their purpose is to damp vertical and ~o horizontal excursion of the car body and, importantly, they are inclined in~ardly and upwardly to minimize the efcct ~ 20.

o~ vertical track surface irregularities on lateral motion of the car body.

It has been found very advantageous to have a tow bar which interconnects one steering arm with the body of the car or other vehicle. The tow bar comprises the steering link L, in the diagrammatic representations of Figure 4, and it appears at 48 in Figures 5, 6 and 9. Its disposition and point of securement to the car body are unique as has already been explained with reference to Fig-ure 4.

As best shown in Figures 5 and 9, the tow bar 48 has an arcuately formed portion 49 intermediate its ends and this portion 49 is journaled within and cooperates with spaced, confronting arcuate flanges 50,50, carried by the central part of the upper edges of the tie-bar 44. This cooperation provides for swinging movements of the tow bar about the center of its said arcuately formed portion 49 and permits the side frame assembly to serve as a point of reaction for torque forces imposed by the connection of the ends of the tow bar to one of the steering arms and to the car body. As illustrated in Figures 5 and 6, the left end of the tow bar overlies the steering arm 12, which should be understood as being associated with that axle (10) which is the more remote from the center of the car body. This end is connected to steering arm 12 by pivot ~s ~ 30 mechanism represented by the pin 51. The opposite end of the tow bar extends in the direction of the center of the car body, and its pin 52 is rotatably carried by a tow bar trunnion 53 secured to a portion 41a (Figure 6) of the car sill structure 40, at a point lying -21a-~,. ,,~

-` ` lQf~5190 along the longitudinal cen~er line of the car (Figure 5).
rhe sill structure extends across the car, being, at its outboard ends, relatively narrow in the direction of car ]Length, as appears at 40 in Figure 6, and widening and ex-t:ending downwardly toward the car center. Figure 6 includes a fragmentary showing of this widened and downwardly extended sill portion, at 41a, where steering arm pin 52 is connected, as stated above. Certain portions of this known type of sill structure are omitted from the showing in Figure 6 in order to avoid confusion of lines in the drawing.

As described above with reference to Figure 5, the point of securement of the tow bar 48 to the more remote steering arm 12 is at a point 51 whose location is a func-tion of the truck assembly's wheelbase w, and the distance s between the two truck assemblies, under a car body. The minimum value of the distance x, from the truck center 49 to the point 51, should satisfy the expression xmin = w2 . The primary function of the tow bar is 4 (s + w) to take care of longitudinal forces between the car body and the resiliently mounted wheelsets. Such forces arise, for example, from braking and coupling impacts. In conven-tional trucks, e.g. freight car trucks now in common use, where no tow bar is present, these forces associated with braking and coupling are passed through the bolster and side frames. These forces, particularly the forces caused by coupling impacts, would, if not properly dissipated, cause unacceptable deflections and wear in the elastomeric pads 30 which mount the steering arms to the side frames, and the side frames to the car body.

-2~-.~ , Reference is now had to a modified form of railway truck embodying the invention, and illustrated in Figures 13 through 15. In this somewhat simpler apparatus a cross bo].ster is embodied in the truck, and imposes the weigh~
of the car upon the side frames. Additionally this truck bolster is flexibly associated with the two side frames and serves as the only interconnection between the two.

-22a-~ '3~
In tcrlns of l)asic structure ~or supl~orting the axlc-borllc ~ cclscts, and for ~roviding rcsilicnt damping at thc axlc end portions, and also between the truc~ and the car body, the apparatus is in many respects similar to the embodimcnts already described. Accordingly, like parts bear like designations, with the subscript b. Thus, axles lOb and 11_ are, respectively, carried by generally ~-shaped steering arms 12b and 13b, and each steering arm, as was the case in the preceding embodiment, has a portion ~o extending from its associated axle, with respect to which it has a substantially fixed angularity, to a common region substantially midway between the two axles. Means 14b couples the steering arms with freedom for relative pivotal movement, and with predetermined substantial stiffness against lateral motion in the general direction of axle extension. In this embodiment, the coupling means 14_ (see Figure 15) comprises a pair of studs 55 and 56, each of which extends from an associated one of the steering arms toward the zone of coupling. The stud 55, carried by arm 12b, is recessed as shown at 57, while stud 56 has a reduced, hollow end portion 58 which extends within the recess. Blastomeric material 59, preferably rubber, is interposed between extension 58 and the interior t~àll de-fining the recess 57, and is bonded to the adjoining sur-faces. A bolt 60 serves to retain the parts in assembly.
Again, as was the case with the preceding embodiment, the coupling 14b,through which the steering moments are ex-changed, has considerable lateral stiffness and an angular ~lexibility suficient so that each axle is free to assume a ~osi~ion radial of a curvcd track and free to adjust to track surface irregularities.

As shown in the cross-sectional portions of Figurc 23.

51~() 13, which is taken as indicated by the line 13-13 applied to Figure 14, it will be seen that each steerinq arm has journal box structure 61, at each end thereof, and in this case flanging, shown at 62, projects from the journal box structure in the direction of the length of the truck.
The journal box has an upper substantially flat surface 63 upon which is seated an elastomeric pad 64. These pads may be sandwiched in steel and, if desired, mounted upon the surface 63 in the manner already described with respect to Figures 5 - 8. The axles lOb and llb are supported by structure which is of the character already described with respect to the earlier embodiment, and which fits within the downwardly facing pedestal opening provided by jaws 68. In practice, means (now shown) would be provided to -retain the axle and the bearing adapter structure within the pedestal opening. Brakes have also not been illustrated, since in this embodiment, they would either be conventional or be of the kind already described with respect to Figures 5, 6 and 9.

In accordance with various embodiments of my inven-tion, the truck side frames 65,65 are carried upon the bear-ing portions of steering arms and, importantly, are sup-ported upon the pads 64, as appears to good advantage in Figure 14. Such pads have been shown at each end of each ; 2~ axle, although it will now be understood that they may be . used at the ends of one axle only, or that pads providing ':

-~4-' ,:

clifferent degrees of flexible restraint may be used with each axle. These pads, as will now be understood, restrain t:he steering motions of the axles with respect to each other and oppose departure of the subtrucks, which are comprised of the wheelsets and steering arms, from a position in which the wheelsets are parallel. Each side frame comprises a -24a-vertically extending web portion 66 having horizon~al flanging 67 (Figure 13) extending laterally from each side of the web. The f]anging tapers from a substantial width in the central region, between the two steering arms, to a relatively narrow width where the arm overlies the pads 64. Each side frame has a pedestal opening between pedestal jaws 68 tFigure 14~ which straddles the journal box assembly and is restrained thereon by cooperation with the interior surfaces 69 of flanges 62, in the manner shown in Figure 13. Each side frame 65 is provided with a generally rec- -tangular aperture 70 tFigure 14), the upper portion of which accommodates th~ end portions 72 of a truck bolster 71, and provides a seating surface for the springs 73 (in this case six are provided), which react between the side frame 65, at 74 as shown in Figure 14, and the undersurface of the projecting end 72 of the truck bolster 71.
The bolster extends laterally of the width of the truck and provides articulated connection means between the two side framas. In this instance no tie-bar i5 used. The bolster ends, since they pass freely through upper portions of the side frame apertures 70, flexibly interconnect the side frames with the freedom for relative tilting movements which is characteristic Qf this invention. In a center par~ of the bolster, overlying the means 14b which couples the steering arms, there is a bowl-type receiver 75, for the car body center plate which, as will be understood by those skilled in this art, is fastened to the car"; center sill, which is not illustrated, To provide the resilient restraint identified as ke, in the description with reference to Pigures 1 and 2, that is the res*raint between the truck and the car body, 25.

a pair of cl;lstorncric pads 76,76 are carried, at spaced por-tions of thc uppcr surface of truck bolster 71, being held there in any desire~ manner, and are coo~era~le with the car bolster (llOt shown) which forms part of the sill struc-ture. The function of these ~ads will be understood with-out further description. It should also be understood that a less suitable, but in some cases adequate, yaw restraint of the truck bolster can be provided by a conventional cen-ter plate and side bearing arrangement.

In Pigure 16, there is illustrated another mod-ified embodiment of the in~ention which, in this case, need be shown in plan view only. This embodim,e~t adapts the principles of the invention to truck ap~aratus in which the side frames and bearings lie inboard of the wheels 25c;
rather than outboard thereof. This apparatus has a number of advantages, ;.e. the wheelsets are lighter, the axles are shorter, the bending moments in the axles are less and the steering arms and the associated'mechanism may be of lighter construction, since they are smaller. The axles are shown at lOc and llc, and the steering arms at 12c and 13c. Coupling means between the steering arms is shown at 14c and may, in this embodiment, take su~stantially the form shown and described in detail ~ith reference to Pigure 15. A relatively flexible tie-bar 44c interconnects the two side ~rames 77,77. The construction and function of this tie-bar and of the central arcuate, seat structure 78 which it supports, is similar to the construction and oper-ation of the corresponding parts already described with respect to the embodiment of Fi~ures S and 6. Each steering arm has journal box structure 79, and each jour-nal box structure suplorts an elastomeric pad 80 OT 80' .

- 26.

.

` - 10~
Thcse pa~s, ~hich cooperate with the journal box and with cJId portions of tllc sidc fralllc structure 77 in the manner shown in ~i~urcs 13 and 14, serYe the s~me purpose as is served by the pads 30 and 30' of the embodiment of Fi~ures 5, 6 and 9, and by thc pads 64 of the embodiment of Figures 13 and 14. This purpose is, of course, consistent with the principlcs shown schematically in Figures 1 and 2, and embodied in that structure by resilient restraint ka~ A
truck bolster 71c is supported upon resilient members 38c, c and the upper surface of the bolster carries a pair of spaced bearing pads 43c, 43c which are disposed for contact with the car body. Tl~ese pads serve the purpose of pads 43, in Figure 9.

In the embodiment of Figure 16 a tow bar is also utilized. This bar (48c) is mounted for rotation about a region intermediate its ends, as described with reference to Figure 5, and has pivot structure shown at 51c and 52c for cooperation, respectively, with the steering arm 12c and the car body, in the manner described with reference to ~v Figures 4, 5 and 6. Brakes shown at 23c are carried by the side frames.

Figures 17 and 18 show alternative structure which is useful to provide some input to the steering action from lateral forces while limiting side-frame-to-steering-arm movement. This apparatus, which is shown as applied to journal box and side frame apparatus of the kind appearing in Figures 5 and 6, is particularly useful where there is no tow bar to provide coupling between the motion of the car bo~y Wit]l respect to the trucX and stccrin~ motion of

3~ the truck, as described with reference to Figures 5 and 6.
In this embo-liment, journal box structure 18d carries 27.

- lnt~ o flanging ~ ct~e~n t~rl~ich is rccciYe~ an elastomcric ~ad 30d and a side fra~e apparatus 32d, all as sho-~n and des-cribed ~itll rcfcrcnce to Figures S an~ 6. Sr~lall stops 81 are eacll carried by one of the flanges ~ and they are so positioned that the lateral forces bctween the side frame and the steering arm are transferred primarily through the stops rather than through the pads 30d. The eccentricity of these lateral stops tthey are disposed eccentrically with respect to the center line of the axle, when viewed ~o in plan) introduces a desirable steering action caused by lateral force. The direction of the steering action is chosen for stability to cause the wheelsets to turn in that direction which tends to keep them centered under the car body.

Finally, further reference should be made to the unique braking apparatus characteristic of the invcntion and to the advantages which are achieved thereby. In prior brake apparatus commonly used in the railroad art, the brake beam is supported by an extension member which 20 rides in a slot in the truck frame. This system has several substantial drawbacks. . The friction created at the slot interferes with prccise control of the force be-tween the wheel tread and the brake shoe, and the radial distance between the friction face of the shoe and its point of support in the slot, results in an overturning moment on the brake shoe which, in turn, causes large variations in the unit pressure between the shoe and the wheel tread, along tl-e length of the shoe face. ~nother problem with conventional brake rigging is tl-e large latcral clearance between the bra~e beams and the car truck side frames. ~iit}l conventional trucks this clear-ancc is required to prevent high lateral forces which 28.

ln~s~o woul~ occur if the ~istortion of thc truck fra~ing in curves is limitcd by contact betwcen the brake shoes and thc wheel flangcs. The a~ove problems can combine to produce stuck brakes~ overheated wheels, wcaring contact of the brake shoes with the wheel flanges, and even de-railment due to wheel failure.

In the brakin~ arrangement shown in Pigures 7, 8 and 8a, these disadvantages are oYercome, primarily because the association of the brake beams with the steer-~ ing arms makes it possible virtually to eliminate unevenwear at the shoe and com~letely to prevent any contact between the shoes and the wheel flanges. Since the brake beams 24 are carried by hangers 27 which are supported in pad structures 28, formed integrally with the steering arms, and because of the fixed angular relationship between the wheelsets an~ the steering arms, the brake pads 26 always remain properly centered with respect to the wheel treads.

Figure 8 shows how the proper choice of geometr-ical relationships can.be used to provide two different ~o values for the braking force B on the leading and trail-ing wheelsets. This compensates for the transfer of weight from the trailing to ;the leading wheelset during braking. Thus, providing this compensation reduces the risk of wheel sliding. The braking effcct on the lead wheelset BL is made larger than the braking effect on tha trailing wheelset, BT, by choosing a center line for the hanger structure 27 which is incline~ with respect to a line t, which is tangent to the wheel surface at the center of the brake shoe face. Referring to the two 3c force ~olygons which comprise ~i~urc 8a, it can ~c sccn that the e~fect of thc mcntione~ anglc is to crcate an 2~.
.

O
anglc ~CtWCCII thc vectors l~L and BL, and the vectors RT
and BT. The prcscnce of thcse angles causes the normal force NL , between the S]IOC and the lead wheel, to be 'Larger than the force ~T between the shoe and the trailing wlleel. It is necessary to have the same ratio between the normal forces N and the braking force~ ~, for both wheelsets, and the ratio is established by the coefficient of friction chosen for the bra~e shoe material an~ the steel face of the wheel.

The total force applied to the brakes is shown in the drawings by arrows appearing on the brake beam linkage in Figures 7 and 8. As shown by the force polygon, the braking force applied to the beam linkage at the leading, or right hand, wheelset is F2, while the force applied to the linkage at the trailing wheelset, is represented in the polygon as the equal and opposite Fl. Since two brake shoes are actuated by each beam assembly, the arrow show-ing brake actuator force for the leading wheelset is.labeled 2F2 ~ while the brake actuator force is labeled on the trailing wheelset as amounting to 2Fl. As will be under-stood, this force can be supplied by any convenient con-ventional means (not shown), adap~ed to apply the force in the direction o~ the arrows shown on the center strut of the brake beam structure.

As indicated ab~ve, this apparatus substantially reduces brake shoe wear and results in much safer bra~ing.

In summary, the apparatus shown in the several ermbodirllents of the invention base~, as it is, on recog-nition of the important part played by control of yaw and lateral stiffness, virtually eliminates flange contact . 30.

in curves and greatly reduces flange forces when contact does occur. In addition, excellent high speed stability is achieved, with resultant minimization of wear and cost problems. As will now be understood, these advantages are achieved by providing restraining means between the side frames and the steering arms of a truck, to restrain yaw-ing motion of the axles, by having the steering arms coupled through further restraining means, and by providing suit-able restraining means between the side frames, or their associated bolster, and the body of the vehicle. Use of equal restraint between the side frames and the steering arms at each side, e.g. the four pads 30 in the embodiment of Figures 5 and 6, has the advantage of minimizing parts inventory and simplifying assembly and maintenance. Use of unequal restraint, which in some instances can be done by eliminating restraining pads at one axle, can further improve the radial steering action desired during curving.

Limiting the side frame car body forces, as for example by the use of the tow bar, is highly advantageous for reasons which will now be understood, while the use of eccentric lateral stops between the steering arms and the side frames can, in certain instances, provide a stabil-izing benefit similar to that achieved by the tow bar steer-ing linkage.

~ Q ~cj~ ~ o Various aspects of the invention have been analyzed mathematically, and illustrated schematically, as well as being shown and described with reference to several struc-tural embodiments. While the emphasis herein has been on the use of elastomeric restraints, similar advantages can be achieved -31a-ln~
by the use of rcsilicnt steel springs. The use of elas-t:omcric rcstraints, llo~evcr, llas the a~vantage of simultancously providing side-franle-to-car-body elas-l:icity, whilc also pr~viding both vertical and lateral l-lexibility in tlle suspcnsion.

In general, however, it will be understood that the use of steel restraints, or of such other structural modifications as properly come within the terms of the appended claims, are within the scope of this invention.

3~.

.

Claims (19)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. In combination with a railway vehicle, a truck assembly comprising: main truck framing; first means movably associating said framing in load-bearing relation with the railway vehicle; a pair of subtrucks each movably coupled to said main truck framing and each carrying an axle-borne wheelset, each said subtruck having a portion extending from its associated wheelset to a common region substantially midway between the two axles; means in said region resil-iently coupling said subtrucks to one another, independently of yaw-inducing connection with said framing, for conjoint steering motions and consequent positioning of their axles radially of a curved track; and resilient means interposed between spaced portions of at least one subtruck and said main truck framing, said resilient means being arranged to oppose departure of said subtrucks from a position in which the wheelsets are parallel.

2. Apparatus in accordance with Claim 1, and in which each subtruck has a pair of spaced portions each of which carries axle bearing support means, and in which said resilient means is disposed to react between at least certain of said bearing support means and said main truck framing.

3. Apparatus in accordance with Claim 1, and in which each subtruck has a pair of spaced portions each of which carries axle bearing support means, and in which said resilient means comprises pads of elastomeric mater-ial, each pad being sandwiched between relatively thin metal sheets, with one metal sheet disposed to be supported by a surface of said bearing support means, and the other metal sheet disposed in load-bearing relation with respect to said main truck framing.

4. In combination with a vehicle, a truck compris-ing; at least two load-carrying axles, movable to different relative angularities therebetween in a horizontal plane, each of said axles having a pair of spaced-apart flanged wheels mounted thereon and adapted to transmit weight from the axle to the running surface on which the wheels roll;
a pair of steering arms, one for each of said two axles, each steering arm having means for mounting its associated axle, and having in relation to its associated axle a sub-stantially fixed angularity in a horizontal plane, and each steering arm extending from its associated axle to a common region substantially midway between said two axles; means in said region pivotally connecting one steering arm directly to the other thereof for transmitting steering forces between the axles, and yieldingly resisting lateral motion of the coupling means in the direction of axle extension; framing spanning the two axles in regions offset from the centers of the two axles; means associated with said framing for transmitting vehicle weight to the steering arms and thence to the axles independently of said means for connecting the steering arms; and elastic means disposed to react between the steering arm and the framing, in said offset regions of at least one axle, said plastic means being of stiffness sufficient to provide restraint of the steering motions of the axles with respect to each other.

5. Apparatus in accordance with Claim 4, and in which said elastic means comprises pads of elastomeric material interposed between the steering arm and the fram-ing.

6. Apparatus in accordance with Claim 4, and in which said elastic means comprises pads of elastomeric material interposed between the steering arm and the framing in the region of only that axle which is more remote from the center of the vehicle.

7. Apparatus in accordance with Claim 4, and further including bolster means spanning the truck, in the direction of axle extension, and elastic means cooperable with said bolster means to restrain motions of the axles with respect to the vehicle.

8. Apparatus in accordance with Claim 4, and further characterized in that said means pivotally connect-ing the steering arms is independent of lateral force trans-mitting connection with said framing and displaceable to accommodate conjoint swinging of said steering arms and consequent positioning of their axles substantially radially of a curved track.

9. Apparatus in accordance with, Claim 4, and further including a brake disposed for cooperation with the tread of each wheel of each axle; brake beam means for each axle, coupled to the brakes for the wheels of that axle; means for applying force to each brake beam means, to apply the shoe of each brake to the tread of its asso-ciated wheel; and means preventing movement of the brakes in the direction of axle extension, whereby to prevent con-tact between the brakes and the wheel flanges, said means preventing movement of the brakes comprising structure so coupling each brake beam means, and the steering arm which supports the corresponding axle, as to prevent displacement of the brake beam means in the direction of axle extension.

10. Apparatus in accordance with Claim 9, and in which there is included means so supporting the brakes with respect to the wheels, as to insure that the normal force between a leading wheel and the shoe of its brake is greater than the normal force between a trailing wheel and the shoe of its brake.

11. Apparatus according to Claim 4, and further including means for limiting the maximum value of wheel flange forces in sharp curves, said limiting means compris-ing a relatively low friction pad disposed to bear vehicle weight and slidable in response to substantial flange forces, to thereby limit the same.

12. Apparatus in accordance with Claim 1, and in which: said main truck framing includes a pair of spaced, generally parallel, framing elements flexibly interconnected by a weight-carrying truck bolster member which extends be-tween said elements and has end portions each of which is movably linked to a mid-portion of a corresponding one of said framing elements; and in which there is further included at least a pair of elastomeric pads disposed to react between said vehicle and spaced areas of said truck bolster member.

13. In a railway vehicle truck assembly: main truck framing having provision for pivotal association with a railway vehicle; a pair of subtrucks each movably coupled to said main truck framing and each carrying an axle-borne wheelset, each said subtruck having a portion extending from its associated wheelset to a common region substantially midway between the two axles; means in said region inde-pendent of such pivotal association means coupling said subtrucks, independently of said main truck framing, with freedom for conjoint yawing motions, and consequent posi-tioning of their axles radially of a curved track, and for differential displacement of said subtrucks in the yaw direc-tion; resilient means of predetermined stiffness constructed and arranged to oppose departure of said subtrucks from a position in which the wheelsets are parallel; and further resilient means constructed and arranged to oppose such differential displacement.

14. A truck assembly in accordance with Claim 13, and further characterized in that: said main truck framing includes a pair of truck side frames each spanning a pair of adjacent axle ends and providing support thereof, said side frames transmitting vehicle weight to the subtrucks and thence to the axles independently of said means coupling said subtrucks; said resilient means being disposed to react between the ends of at least one axle and said side frames.

15. In a vehicle having at least one pair of axle-borne wheelsets the axles of which are longitudinally spaced from the center of the vehicle in generally parallel adjacency and lie in a plane within which said axles may yaw, apparatus for mounting said wheelsets upon said vehicle including mechanism for transmitting load from the vehicle to the wheelsets and providing for relative pivotal, yawing, move-ments of the axles in said plane, as the wheels roll on a running surface, said apparatus comprising: a pair of frame structures, each coupled to an associated one of said axles in such manner that each axle has a substantially fixed angularity with respect to its frame structure in said plane, each frame structure having a portion extending from its associated axle to a common region substantially midway between said two axles; means coupling said frame structures directly to one another in said region, and inde-pendently of said load transmitting mechanism, for relative yawing movement, and with predetermined stiffness against motions in the general direction of axle extension; a pair of side frame members each extending to and spanning a pair of adjacent end portions of the two axles, said frame mem-bers being free for relative tilting movements in said plane;
means forming connections coupling each end portion of each axle, and its frame structure, to the adjacent side frame member, the connections coupling the ends of that axle which is more remote from the center of said vehicle, with the adjacent side frame members, including means providing elas-tic restraint of predetermined stiffness against yawing movements of the latter axle; and means coupling each side frame member to said vehicle and including other elastic restraint means providing predetermined yaw stiffness be-tween said frame members and the vehicle.

16. Apparatus in accordance with Claim 15, and further including bolster means spanning said side frame members and imposing the vehicle load upon said frame mem-bers, said other restraint means cooperating with said bol-ster means to couple each side frame member to said vehicle, and providing restraint of the motion between said frame members and the vehicle.

17. A railway truck assembly in accordance with Claim 13, and further including: means disposed eccentrically with respect to the center line of the axle when viewed in plan, and cooperative with the subtrucks, and with the main truck framing, to transmit lateral forces between the subtrucks and said main truck framing.

18. Apparatus in accordance with Claim 17, and in which said subtrucks include bearing support means pro-vided with spaced flanges between which said framing portions are received, and said last means comprises stops carried by said flanges.

19. In a railway vehicle truck, having main framing and a pair of axle-borne wheelsets each carried by a steering arm which has spaced portions journalling its associated wheelset, and which steering arms have means pivotally connect-ing them directly to one another, in a region substantially midway between said two axles, and accommodating positioning of the axles radially of a curved track, to insure that steer-ing moments are freely exchanged between said wheelsets, means for minimizing wheel-flange-to-rail contact, and for maximizing high speed stability, said means comprising:
first elastomeric means proportioned and disposed to provide each wheelset with a predetermined value of yaw stiffness with respect to the main framing; second elastomeric means proportioned and disposed to provide a predetermined value of yaw stiffness between the main framing and the vehicle body; and third elastomeric means proportioned and disposed to resist differential displacement of said steering arms while permitting exchange of such steering moments between the wheelsets and thereby permit each axle to assume a position radial of a curved track, said third elastomeric means being located in the region of said means pivotally connecting the steering arms to one another and reacting between said steering arms.