CA1213471A - Multiple axle self-steering powered locomotive truck - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:

A powered locomotive truck is disclosed, the truck having two wheelsets, each with an axle having a driving motor mounted thereon, the wheelsets being mounted in a rigid main truck frame, with freedom for relative yaw motion of the wheelsets, and each wheelset further having a steering arm or yoke movable with its wheelset during relative yaw motion of the wheelsets with respect to each other, the steering arms having an interconnection in a region between the wheelsets providing for interchange of yawing steering forces between the wheelsets.

Description

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MULTIPLE AXLE SELF-STEERIMG
POWERED LOCOMOTIVE TUCK

CROSS References Jo :

The present application relates to improvements in my prior Canadian application Serial No. 336,776, filed October 1, 1~79, and also in my prior Canadian Patent No.
1,065,190, issued October 30, 1979.

BACKGROUND AND STATEMENT OF OBJECTS:

Certain forms of multiple axle self-steering rail-way trucks are known, particularly for use in railway cars.
Several forms of such self-steering car trucks are disclosed in the above identified prior applications. The truck arrange-mints disclosed in my prior applications comprise a pair of axle wheel sets mounted in a truck frame structure with freedom for relative yaw motion of the axles and each axle wiliest having a steering arm, with the two steering arms interconnected in a region between the axles to provide for interchange of steering forces between the steering arms and thus provide for interchange of steering forces between the wheel sets in the yawing sense.

In said prior applications, arrangements are shown in which the devices which interconnect the steering arms are arranged to interchange the steering forces between the steering arms and the wheel sets independently of yaw-inducing connection with the main frame or other parts of I I

the truck structure. The foregoing provides self-steeing action of such effectiveness and accuracy as to virtually eliminate the angle of attract between the wheel flanges and the rails on which the truck is traveling. Smoother tracking is thereby provided under all conditions. This greatly reduces noise and wear between the wheels and rails in curves, improves high speed stability and ride quality with reduced maintenance of the track, trucks and car structure.

One of the principal objectives of the present invention is to provide a self-steering action of the char-cater just referred to in a powered truck of a locomotive and to adapt this self-steering character to the powered truck of a locomotive in such a manner as to provide for effective delivery of the driving force from the driven wheel sets to the main frame of the truck and thus to the locomotive itself, notwithstanding the freedom provided for the self-steering activity of the wheel sets in the yaw-in sense.

Another objective of the present invention is to provide a novel arrangement of brakes and brake parts for the driven wheels the brake equipment being mounted at least in part on the main frame of the truck, but being arranged to accommodate yawing motions of the wheel sets even at times during the application of the brakes.

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In one preferred embodiment according to the pros-en invention, the powered truck incorporates two wheel-sets, each provided with a steering arm and each of which wheel sets is independently motorized, i.e., the axle of each wiliest carries its own driving motor, and means are provided for transmitting motor torque forces directly from the motor to the truck frame In another embodiment, means are provided for transmitting torque forces through the steering arms to the truck frame It is a further object of the present invention to provide a pivotal interconnection structure between the steering arms associated with each axle wiliest, the in-terconnection structure being arranged to transmit traction forces between the steering arms, provision also being made to transmit traction forces from the steering arms to the truck frame in various different relatively angled post-lions of the steering arms.

In summary of the foregoing and of other features of the present invention, it will be seen that it is a gent oral objective of this invention to improve the tracking behavior of railway locomotive trucks, particularly a two-axle or Tolstoy truck. Such improvement in the track-in behavior increases the adhesion available for traction and further reduces the flange forces and thus the wear on both the wheels and the track not only in curves but also on straight track.

~13471 Prior art or conventional powered trucks exert lateral forces on the track which are generally much greater than those required to guide the vehicle along the track centerline. In curves, most of the extra lateral force is the result of tracking errors for the leading axle which, in conventional trucks, is restrained to remain parallel with the trailing axle in consequence of which, the lead-in axle will have a substantial angle of attack with no--spent to the rail in the yawing sense This angle of attack not only create unnecessary lateral force, but also causes a substantial loss of potentially available longitudinal adhesion for pulling the train. In curves, additional dye namic forces result from the fact that the leading axle, having a large angle of attack, will tend to follow, in detail, all the irregularities present in the alignment of the rails.

The foregoing disadvantages are virtually elm-inated by the provision of the self-steering arrangement for a powered truck a provided in accordance with the pros-en invention.

In prior art powered trucks operating on straighttrackl there are unnecessary lateral forces arising from unneeded steering action, which lateral forces can be of sufficient magnitude to cause wheel flange-to-rail impact, and such impacts have commonly occurred at a frequency approximating 2 to 5 impacts per second These undesirable 3~7~

motions have arisen with conventional powered trucks in which the axles, while remaining generally parallel to each other, can move individually with substantially no restraint within the longitudinal and lateral clearances present in the mounting of the ale bearing structures in the pedestal jaws of the truck frame.

The selE-steering type of powered truck of the present invention eliminates the unnecessary lateral motions and forces above referred to.

The arrangement of the present invention is adapted or use in powered trucks having axle-hung traction motors.
This type of powered truck is especially subject to tracking errors induced by the combination of pedestal jaw clearances and the lateral forces acting at the motor nose The pod-vestal clearances allow lateral motion of the truck frame relative to the axle. This motion causes an undesirable yaw motion of the motor/axle assembly through the lateral force at the motor nose which is located longitudinally a substantial distance from the axle.

The arrangement of the present invention is effect live in providing self-steering even with axle-hung traction motors. The reason for this is that the motor/axle assembly is firmly guided in yaw by the steering arms without the lost motion of the pedestal clearances. Further, in one embody-mint, the motor nose is supported directly by the steering arm, completely eliminating all influence of lateral motor nose forces.

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Although it is theoretically possible to support the traction motors from the vehicle body or truck frame instead of from the axles, and provide a flexible coupling in the drive train between the motor and the axles, this approach introduces the mechanical complexity of the flex-bye coupling and this is a substantial structural drawback.
On the other hand, the arrangement of the present invention provides the opportunity to support the traction motors from the steering arms. This greatly reduces the motions imposed on the flexible coupling, making this a much more attractive option for removing the traction motor from the unsprung axle weight category.

In summary, it is pointed out that the arrange-mints of the present invention effectively provide for steer-in motions of the powered axles which minimize the wheel/rail angle of attack in curves and also provide a stabilizing restraint of undesirable axle activity on straight track.

In accordance with the present invention, the vertical load-carrying connection between the truck framing and the axles has flexibility in the longitudinal direction to allow for yaw motion of the axles relative to the frame in. The interconnection between the steering arms is arranged in a region midway between the two axles of a two-axle powered truck; and according to the present invention, this interconnection provides for interchange of lateral, ~347~

vertical and longitudinal forces between the two axles, without significantly restraining the relative yaw motion as required in order to permit the axles to assume radial positions with respect to curved track. The interconnect lion also serves to transmit yaw forces from one wiliest to the other. At the same time, in accordance with the present invention, the interconnection between the steering arms provides a relatively stiff restraint of differential steering motion such as would be required for the two axles to assume positions corresponding to the sides of a non-rectangular parallelogram; and this restraint is of import lance in order to provide high-speed stability on straight track.

The foregoing factors are of special importance in a powered truck of a locomotive, because preventing the wheel/rail angle of attack associated with tracking errors causes a consequent increase in the overall adhesion and thus in the utilization of the available power of the drive in motors.

It is also a major objective of the present invent lion to provide for the retrofitting of certain existing powered trucks by adding steering arms and other related equipment to provide the operating advantages above referred to 34~

With the foregoing objectives in mind the pros-en invention provides a powered railway truck comprising a load-carrying Frame a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having freedom for yaw motion of the wiliest with respect to the truck frame, at least one wiliest also having a drive motor mounted on its axle and movable in yaw with the wiliest, a steering arm associated with each wiliest, the wiliest with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheel--sets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheel sets of said pair independently of the truck frame and thereby cause both of the wheel sets to assume radial positions when travel-lying on curved track/J, and for the wiliest having a drive motor, means providing for the transmission of torque react lion forces directly from the motor to the truck frame in-dependently of the steering arm In addition, the present invention also provides a powered railway truck comprising a load-carrying frame, a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having clearance providing freedom for yaw motion ox the wiliest with respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wiliest also having -PA-~2~3~7~

a drive motor mounted on its axle and movable in yaw with the wiliest a steering arm associated with each wiliest, each wiliest with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid region between the pair of wheel-sets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheel sets of said pair independently of the truck frame and thereby cause both of the wheel sets to assume radial positions when travel-lying on curved track, and flexible connection means inter-connecting the steering arm for each wiliest with the truck frame in a region offset from said pivot means beyond the axle of that wiliest and restraining relative lateral motion of the truck frame and the steering arm in said offset region, while permitting yaw motions of the steering arm.

In addition, the present invention also provides a powered railway truck comprising load-carrying framing, a pair of axle wheel sets each having journal bearings mounted to support the truck framing and having clearance providing freedom for yaw motion of the wiliest with respect to the truck frame, resilient load-transmitting means between the journal bearings and the framing, each wiliest also having a drive motor mounted on its axle and movable in yaw with the wiliest, a steering arm associated with each wheel-set, each wiliest with its motor and steering arm being jointly movable in the yaw sense pivot means interconnecting :`;' AL

the steering arms in the mid-region between the pair of wheel sets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheel sets of said pair independently of the truck frame and thereby cause both of the wheel sets to assume radial positions when travel-lying on curved track, means for communicating the traction forces from the steering arms to the truck framing, and sprint means for delivering load from the framing to the wheel sets, said spring means having sufficient yaw flex-ability to substantially avoid communication of traction forces from the wheel sets through the spring means to the truck framing.

Still further, the present invention provides a powered railway truck comprising a load-carrying frame, a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having clearance providing freedom for movement of each wiliest both laterally and longitudinally of the truck and also for relative motion to various different positions in yaw' each wiliest also having a drive motor mounted on its axle and movable with the axle, a steering arm associated with each wiliest, the wiliest with its motor and steering arm being jointly movable in the yaw sense pivot means interconnecting the steering arms in the mid-region between the pair of wheel sets and including means enforcing substantially equal and oppo-site pivotal yawing motion of the wheel sets of said pair -7C~

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independently of the truck frame and thereby cause both of the wheel sets to assume radial positions when travel-lying on curved track, and, for each steering arm, means associated with the steering arm and the truck frame in-eluding an abutment pad positioned to communicate traction forces between the steering arm and the truck frame, the abutment pad being formed to provide surface-to-surface contact, even in various different yaw positions of the steering arm with respect to the truck frame.

In addition, the present invention also provides a powered railway truck comprising a load-carrying frame, a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having clearance providing freedom for yaw motion of the wiliest with respect to the truck frame, at least one wiliest also having a drive motor mounted on its axle and movable in yaw with the wiliest, a steering arm associated with each wiliest, the wiliest with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheel sets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheel sets of said pair index pendently of the truck frame and thereby cause both of the wheel sets to assume radial positions when traveling on curved track, and a sanding device for each motor driven wheel, the sanding device being mounted on the steering arm for the driven wheels.
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Still further, the present invention provides a powered railway truck comprising a load-carrying frame, a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having clearance providing freedom for yaw motion of the wiliest with respect to the truck frame, resilient load-tran~mitting means between the journal bearings and the frame, each wiliest also having a drive motor mounted on its axle and movable in yaw with the wiliest, a steering arm associated with each wiliest, each wiliest with its motor and steering arm being jointly movable in the yaw sense, and pivot means interconnecting the steering arms in the mid-region between the pair of wheel sets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheel sets of said pair independently of the truck frame and thereby cause both of the wheel sets to assume radial positions when travel-lying on curved track, said means comprising an element in-termediate the steering arms, pivots connecting the steering arms to said element independently of each other, and means enforcing substantially equal and opposite pivotal motion of the steering arms with respect to said element.

In addition, the present invention provides a powered railway truck comprising side frame members and transoms interconnected to provide a load-carrying truck frame structure, a pair of axle wheel sets each having journal bearings mounted to support the truck frame and having clear-ante providing freedom for yaw motion of the wiliest with --YE-;, ,~.

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respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wheel-set also having a drive motor mounted on its axle and movable in yaw with the wiliest, a steering arm associated with each wiliest, the wiliest with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelhouses and including means enforcing sub Stan-tidally equal and opposite pivotal yawing motion of the wheel-sets of said pair independently of the truck frame and there-by cause both of the wheel sets to assume radial positions when traveling on curved track, and means for transmitting traction forces and motor torque forces from the steering arms to the truck frame regardless of the relative yaw post-lions of the wheel sets and steering Ayers In addition, the present invention provides a method for retrofitting a powered railroad truck with mock-anise providing for wiliest steering, which method come proses:

a) selecting an existing truck having load-carrying side frame members with two pairs of pedestal jaws each with pedestal liners, two wheel-sets each comprising a pair of wheels fixed on OF

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an axle having a driving motor and axle bearings and bearing adapters received it the pairs of pedestal jaws, the bearing adapters of each pair having load-carrying spring connection with the side frame members, b) removing at least a part of the pedestal liners to provide increased freedom for yaw move-mint of one wiliest with respect to the other wiliest, I applying a steering arm to each wheel-set, the steering arm being connected with the wheel sets to provide for conjoint movement of each wiliest with its steering arm in fixed rota-lion in the yawing sense, d) establishing a pivotal interconnection of one steering arm to the other steering arm in a region offset from the axles in a direction between the wheel sets and thereby provide for coordinated pivotal motion of the wheel sets in the yawing sense and for coordinated interchange of steering forces between the wheel sets, Y

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e) and interconnecting the steering arms to the truck frame members by applying connection means in regions offset from the axles in a direct lion longitudinally of the truck opposite to the direction of offset of the pivotal interconnect lion of the steering arm, said connection means serving to restrain relative lateral motion of the steering arms and truck frame members in said spaced regions and thereby provide for lateral displacement of said pivotal interconnection during coordinated pivotal motion of the wheel sets and steering arms.

Still further, the present invention provides a method for retrofitting a powered railroad truck with mechanism providing for wiliest steering, which method comprises:

a) selecting an existing truck having load-carrying side frame members with two pairs of pedestal jaws each with pedestal liners, two wheel-sets each comprising a pair of wheels fixed on an axle having a driving motor and axle hearings and bearing adapters received in the pairs of pedestal jaws, the bearing adapters of each pair having load-carrying spring connection with the side frame members, and further having brake mock-anise including a brake cylinder at each snide OH

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of the truck and brake-operating connections from each cylinder to the brakes for the two wheels at that side of the truck, b) removing at least a part of the pedestal liners to provide increased freedom for yaw move-mint of one wiliest with respect: to the other wiliest, c) applying a steering arm to each wheel-set, the steering arms being connected with the wheel sets to provide for conjoint movement of each wiliest with its steering arm in fixed rota lion in the yawing sense, d) establishing a pivotal interconnection of one steering arm to the other steering arm in a region offset from the axles in a direction between the wheel sets and thereby provide for coordinated pivotal motion of the wheel sets in the yawing sense and for coordinated interchange of steering forces between the wheel sets, 2Q en and altering the brake-operating con-sections to provide for operating the brakes on the two wheels of one wiliest by one of the brake cylinders, and to provide for operating the brakes on the two wheels of the other wiliest by the other brake cylinder.

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BRIEF DESCRIPTION OF TEE DRAWINGS:

How the foregoing objects and advantages are attained, together with others which will occur to those skilled in the art, will appear more fully from the lot-lowing description taken with the accompanying drawings, in which:

Figure 1 is a side elevation Al view of a known form of powered truck to which the self-steering equipment of the present invention has been applied, portions of the structure being broken away and shown in section in the central region;

Figure 2 is an end view of the truck of Figure 1, with parts in the left hand portion of the view shown in vertical section;

Figure 3 is an enlarged vertical sectional view of the flexible joint or connection between two steering arms;

Figure 4 is a plan view of the truck of Figures 1 to 3 but with certain portions broken away and shown diagrammatically in horizontal section;

Figure 5 is a somewhat diagrammatic elevation Al outline view of another embodiment of the equipment of the present invention applied to a powered truck in order to establish self-steering in the yaw sense;

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Figure 6 is an end view of the truck of Figure 5; and Figure 7 is a plan view of the truck of Figures 5 and 6, with certain parts broken away.

The embodiment illustrated in Figures 1, 2, 3 and 4 represents a form of a powered truck, the general arrangement of which is known, being a conventional truck manufactured by General Motors Corporation, and these fig-uses illustrate that truck retrofitted to incorporate one embodiment of the structure of the present invention.

Figures 5, 6 and 7 diagrammatically illustrate the same form of truck but incorporating certain alterna-live structural embodiments of features of the present in-mention which may be incorporated in such a truck by retry-fitting, or which may be embodied in a newly constructed truck.

DETAILED DESCRIPTION OF FIGURES 1 TO 4:

The powered truck of Figures 1 to 4, as above mentioned, is a known general form of powered truck and embodies two axle wheel sets, each being provided with a separate driving motor mounted on the axle of that wheel-set. At least one such truck is adapted to be positioned under the body of the vehicle or locomotive, and the general arrangement of the principal parts of the truck are men-toned horribly with reference to Figures 1 to 4 inclusive.

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In Figure 2, a portion of the booty of the logo-motive appears at 12. The body of the locomotive is carried by the truck through a central pivot structure 13, received in an upwardly open socket 14 provided on the bolster 15.

The main frame structure of the truck comprises side frame elements 16, and the weight or load of the logo motive is transferred from the bolster 15 to the main side frame elements 16. For this purpose, a swing hanger yoke 17 at each side of the truck having upwardly projecting spaced legs is pivotal connected with one of the side frame elements at the points indicated at 18-18, and a spring plank 19 has its ends received on the base portions of the yokes 17 at opposite sides of the truck. Rubber or other resilient cushions 20 are interposed between the laterally projecting ends of the bolster 15 and the spring plank, so that the weight of the vehicle is transmitted from the bolster through the resilient cushions 20 to the spring plank and thence through the pivotal yokes 17 to the main side frame elements or members 16. The load is transferred from the side frames to the wheel sets in the manner brought out below In certain existing trucks of the general type disclosed in Figures 1 to 4, transversely extended leaf springs are positioned between the bolster 15 and the spring plank 19; and in such trucks, the retrofitting contemplated :,' ~3~7~L

by the present invention includes either replacing such leaf springs with rubber cushions of the type indicated at ED in Figure 2 or retrofitting with the arrangement shown in Figures 5, 6 and 7.

Each side frame member is provided with two pairs of pedestal jaws 21-21, each pair receiving the bearing structure 22 for the outboard portions of the axle of each wiliest. The bearing structures each comprise roller bear-ins in bearing boxes; but these parts form no part of the present invention per so and are, therefore, not illustrated in detail herein. Instead, the bearing structures are shown either in outline only, or for the wiliest toward the left of Figure 4 by a diagrammatic horizontal sectional illustra-lion.

Each axle is, of course, located centrally in its bearing structure for instance, in the region indicated at 23 in Figure 1. A pair of wheels 24 is fixed on the axle of each wiliest, and these wheels are customarily flanged and arranged to travel upon rails, such as indicated at 25 in Figure 2. At each bearing location, appropriate suspension springs 26 are provided through which the weight of the locomotive is transmitted from the side frame members to the bearing structures 22, and thence to the outboard end portions of the axle of each wiliest.

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Between the wheels of each wiliest and mounted upon the axle of that wiliest, a driving motor and gear-in are arranged, as diagrammatically indicated at 27.
These motors are of known construction and are connected with the axle of the wiliest with which the motor is also-elated, and the details of that motor arrangement and con-section are not described herein as they form no part of the present invention per so.

As seen in Figures 1 and 4, a pair of transversely extending longitudinally spaced truck transoms 28 extend between the side frame members 16 in a portion of the truck structure in the mid region of the truck; and in addition, a transom 29 extends between the side frame members at each end of the truck. The side frame members and those transoms thus provide truck structure surrounding the region in which each wiliest and its motor are positioned. With the side frame members and the various transoms, it will be seen that the frame of the truck comprises a unified rigid struck lure, which is in contrast with many other railway railway car trucks, in which the trucks are provided with independent side frames capable of various motions with respect to each other. The interconnected rigid frame structure is cuss tomarily used in powered trucks of locomotives, especially where individual motors are provided on each of a plurality of wheel sets associated with the truck frame.

Lo As appears in Figures 1 and 2, the motor also-elated with each wiliest is supported in part by certain inter engaging motor nose suspension parts provided on the motor structure and on the adjoining transom 28. The transom 28 at each side of the central region carries a pair of motor nose cushion sandwiches 30 formed of interleaved rub-bier and metal layers located relative to the transom 28 by bolts aye. Abutment lugs 31 and aye project from the motor structure and transom respectively and serve to in-terchange torque forces between the motor and the transom through the cushion sandwiches 30. This motor nose sup-pension means is present on the truck being retrofitted.

The portions of the truck of the embodiment of Figures 1 to 4, as described above, are all included in the basic truck structure above referred to as manufactured by the General Motors Corporation; and it is a truck of that known construction which is adapted to be retrofitted according to the present invention in order to incorporate the self-steering features as applied to the motorized axles and wheel sets of that prior known truck. In carrying out the invention, it is, of course, also possible to apply the invention to a truck being newly built, without retry-fitting an existing basic structure.

Attention is now directed to various features of the self-steering mechanisms incorporated in a truck according to the embodiment shown in Figures 1 to 4 inkwell-size, and it is here noted that certain new devices and I

structures are added to the equipment; and in addition, where retrofitting is being effected, certain of the exist-in components, for instance, the brake arrangements, are modified in order to provide effective brake operation in the self-steering type of powered truck contemplated accord-in to the invention.

It is first noted that, as clearly appears in Figure 4, substantial clearance is needed between the pedestal jaws 21 and the bearing structures 22 associated with each wiliest. This clearance provides freedom for relative angling or yawing of the wheel sets with respect to the main truck frame structure. In the case of retrofitting, the clearance may be provided by removing pedestal liners which are ordinarily present in such a truck. If desired, the pedestal liners may either be replaced with pedestal liners of smaller thickness, or the original liners may be ground to provide a thinner liner and, therefore, provide the no squired clearance. The liners are customarily of channel shape, in view of which removal thereof not only provides clearance in the fore-and-aft direction but also transversely of the truck. It is pointed out that the lateral movement restraint of certain roller-bearing arrangements normally provided by limiting the lateral pedestal clearance is pro-voided in the arrangement of the present invention by the connection of the wheel sets to the steering arms described below.

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The self-steering truck according to Figures 1 to 4, whether retrofitted or newly constructed, incorporates a "steering arm" for each wiliest. Herein, this term "steering arm" is used to identify the structure associated with each wiliest which is required in order to provide for the self-steering function; and it is to be understood that this structure may take a variety of different forms.
Thus, it may comprise a transverse bar having an arm ox-tended from each end toward the axle, or it may comprise a structure or yoke extended around the entire wiliest, as it the case in the illustration of figures 1 to 4.
Unless otherwise indicated, the term "steering arm" as used herein is to be understood in a generic sense.

Each of the steering arms comprises several dip-fervent but interconnected structural pieces. Thus, a long-tudinally extending channel or beam 32 extends fore-and-aft of the truck in the region of each bearing structure 22 and is secured to that bearing structure as indicated at 33. The outer ends of each pair of channel members 32 are interconnected by a transversely extending tube or brace 34. The yoke or steering arm for each wiliest further includes inwardly converging portions 35 which are inter-connected by a transverse beam 36. The steering arm of this embodiment includes the parts identified by the rev-erroneous numerals 32, 34, 35 and 36 thus constitutes a yoke completely surrounding each wiliest.

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The two steering arms are interconnected by means of a pivot structure which is preferably located in the central region of the longitudinal and transverse axes of the truck. As best seen in Figure 3, this interconnection between the transverse beams 36 and 36 of the two steering arms comprises a central vertical pin 37 which is mounted by means of plates 38 secured to one of the beams 36. The pin 37 serves to mount a central ball element 39, with its outer curved surface received in a socket 40 provided on the other transverse beam 36. A rubber or resilient liner 41 is provided between the spherical surfaces of the ball 39 and the socket 40; and as is clearly seen in the claw-inks clearances are provided so that the interconnected steering arms for the two wheel sets may not only partial-pate in relative yawing motions, but may also participate in other relative motions, including relative lateral and longitudinal tilting of the steering arms and thus of the wheel sets.

Since the side frames of this general type of truck structure are interconnected and the truck f faming has rigidity it becomes practical to employ a form of trays-verse link 7 interconnection between the steering arms and the truck frame. This connection is arranged in a manner which will not interfere with the desired relative yawing motion of the two steering arms and the associated wheel-sets. In the embodiment shown in Figures 1 to 4, the ~3~7~

connection also constitutes a portion of the retrofitting equipment, in the event the arrangement is being applied to an existing truck. The connection comprises a generally transverse link 42 for each steering arm, the link having a connecting joint 43 a one end through which the link is connected with the steering arm, and also having a con-netting joint 44 between the other end of the link and the cross transom member 29 of the truck frame. Preferably, each of the connecting joints is flexible to accommodate I relative angling of the steering arms and truck frame struck lure. Desirably, these joints include resilient components to absorb minor relative motions and vibrations.

Because of the presence of these links, when the truck enters a curve and yawing forces are intercommunicated between the two steering arms through the interconnecting joint formed of the parts identified as 37 to 41, the rota-live yawing motion of the links is accommodated by a slight shifting movement of the interconnecting joint transversely of the truck. At the same time, because of the arrangement and characteristics of the interconnecting joint as above described, that joint will not only accommodate the relative yawing motion of the steering arms and thus of the wheel sets in the yawing sense, but will also accommodate other rota-live motions of the steering arms and wheel sets, particularly 3~7~

relative lateral and longitudinal tilting motions thereof.
This form of transverse link interconnection between the truck frame having rigidly interconnected side frame members and the steering arm not only serves the functions referred to above, but is of particular importance in maintaining stability of operation at high speeds.

In accordance with the embodiment disclosed in Figures 1 to 4, special provision is made for interchange of the motor inactive forces from the steering arms to the truck frame, notwithstanding the relative yawing or steer-in of the axles For this purpose, see particularly Fig-uses 1 and 4, the cross beam 36 of each steering arm is provided with an abutment pad 45, being presented toward a cooperating pad 46 which is applied to the surface of the truck transom 28 presented toward the cross beam 360 As seen in Figure 4, these abutment pads are provided at both sides of the central joint interconnecting the steer-in arms Because of this arrangement, the inactive effort generated by the motor associated with a given wiliest will be communicated to the truck frame through the steer-in arm for that wiliest and thence through the pair of abutment pads 45 and 46. When the truck is being driven in one direction, for instance, toward the right when viewed as in Figure 4, the inactive force generated by the motor-iced wiliest toward the left of Figure 4 will be commune-acted through the steering arm for the left wiliest to I

and through the central interconnecting joint between the two steering arms and thence through the abutment pads 45 and 46 at the right hand side of the central joint. When the vehicle is being power driven in the opposite direction, the abutment pads 45 and 46 at the left of the central joint as viewed in Figure 4, will receive the inactive force of both wheel sets and communicate that force to the truck frame through the transom 28 positioned at the left of the central joint.

It is contemplated that the abutment pads 45 and 46 be arranged to maintain surace-to-surface contact not-withstanding yawing as well as other angular motions of the steering arms. For this purpose, rubber pads may be used under the metal abutment pads. Alternatively, the abutment pads may be formed of a material having resilient characteristics as well as wear resistance. For this pun-pose, the pads may be formed of polyurethane.

A known truck of the general construction shown in Figures 1 to 4 also incorporates brake cylinders 47 and 48, one being mounted toward one end of the truck frame at one side thereof, and the other being mounted toward the other end of the truck frame toward the opposite end thereof, as clearly appears in Figure 4. In a truck of ~3~7~

the kind referred to and adapted to be retrofitted accord-in to the present invention, the brake-applying cylinder 47 is provided with brake-operating links and levers ox-tended to the two brake shoes 49 and 50 associated with the wheels 24 toward one side of the truck frame: and the other brake-applying cylinder 48 is provided with brake-operating links and levers extended to the two brake shoes 51 and 52 associated with the wheels 24 positioned toward the opposite side of the truck frame. Because of the in-lo production of the steering arms and the consequent steering motions between the two wheel sets, the present invention contemplates changing the brake rigging in order to provide for the application of the brake shoes I and 51 associated with one wiliest under the influence of one brake-applying cylinder 47; and in order to provide for the application of the brake shoes 50 and 52 associated with the other wheel-set under the influence of the other brake-applying cylinder 4B. The retrofitting to effect this change is desirable to limit the travel of the pistons in the brake-applying cylinders 47 and 48. The effective range of travel would be likely to be exceeded if the original brake rigging was retained in the truck modified to introduce the steering arms. however) with the retrofitted brake rigging arrange-mint, the brake cylinder travel is not increased by the steering or yawing motions of the wiliest.

rrJ~ 9 AL

The retrofit brake rigging may be of various kinds; but in a typical example, such as illustrated in Figures 1 to 4, the cylinder 47 is connected with a gent orally horizontal lever 53 pivoted on the top of the side frame of the truck as indicated at 54 in Figure 4, the inner end of the lever 53 being flexibly connected wit to the up-right lever 55 see Figure 1) on which the brake shoe 49 is mounted by the joint indicated at 56. This joint also connects the lever 62 with the brake shoe, and the lever 62 is pivoted to the side frame as shown in Figure 1, thereby providing for vertical and lateral support of the brake shoe in the proper position to contact the wheel. A link 57 extends generally horizontally longitudinally of the truck from the lower end of the upright lever 55 and, in turn, is connected with one end of the transverse lever 58 which is pivotal mounted at 59 to a downwardly pro-jetting portion 60 of a frame transom as appears in Figure

2. The other end of the lever 58 is connected by the link 61 (see Figure 4) with the low r end of the upright brake-I applying lever aye on which the brake shoe 51 at the other side of the truck is mounted in the same general manner as the shoe 49 is mounted on the lever 55. The lever aye, however, is preferably pivotal mounted on the adjacent side frame member, for instance, in the manner shown for the lever aye for the other wiliest appearing toward the right of Figure 1.

I
Similar brake parts are provided in the intercom-section of the cylinder 48 with the brake shoes 52 and 50 for the other wiliest.

Wheel sanders 63 may be provided as shown in Fig-use 1, and in a truck embodying the steering arms are pro-fireball mounted on a portion of the steering arms, for in stance, on the transverse beams 34 above referred to. In the retrofitting of a known truck, it is preferred to no-locate the sanders from mounting on a portion of the truck frame to a mounting on a portion of the steering arms.

Four damper devices such as indicated at 64 are also desirably applied, for instance, two at each end of the truck between portions of the main frame and portions of the steering arms, as clearly shown in Figure 1. These damper devices are connected to the frame and steering arms by flexible joints adapted to accommodate the relative angle in motions of the steering arms. These dampers serve to control the vertical, roll and pitching motions of the logo-motive car body and the truck frame. It should be noted that four dampers are shown rather than the customary two only at diagonally opposite corners of the main truck frame.
The two additional dampers are needed in large part because pedestal/bearing box friction is eliminated by the use of steering arms. It should also be noted that the combination I

of steering arms and four dampers will improve the logo-motive ride quality because pedestal/bearing box friction varies widely and it often not adequate to control ride.
This friction also can cause unwanted wheel lift under full power conditions, adding to the derailment hazard.

DETAILED DESCRIPTION OF FIGURES, 6 AND 7:

Thy embodiment of the self-steering mechanism shown in Figures 5, 6 and 7, although differing structurally from the embodiment of Figures 1 to 4, is also capable of I being used in a retrofitting operation on a truck of the same kind as referred to above in connection with the descrip-lion of Figures 1 to 40 The mechanism of Figures 5, 6 and 7 is also capable of use in newly constructed trucks of various forms. This arrangement offers the potential for employing strotlger steering arms which can accommodate the motor nose suspension forces and even completely support the traction motor.

It is first noted that in Figure 5, the truck side frame member shown and identified by the numeral 16 I is of the same general configuration as the truck side frames of the truck being retrofitted in the first embodiment.
However, in Figures 5, 6 and 7, the frame and various ~3~7~

other parts are shown in much more simplified or diagram-matte fashion; and in addition, many components of the truck shown in Figures 1 to 4 have been completely omitted from the illustrations in Figures 5, 6 and 7. It is to be under-stood that the following description of the second embody-mint is given with respect to the showing in Figures S, 6 and 7, even though those figure numbers are not spy-focally referred to.

As in the first embodiment, the steering arms of the second embodiment also comprise yoke structures sun rounding the wheel sets and motors. The wheels are India acted by the numeral 24 and the axle of each wiliest is here diagrammatically indicated at 65, the motors being shown in dotted outline at 27, as in the first embodiment.
The wheels are again shown as riding upon the rails 25.

The yoke comprising each steering arm is India acted at 66. Here the yoke is positioned with its side legs underlying the journal bearings 67 and is fastened to the journal bearings, for instance, as diagrammatically indicated at 68.

In this embodiment, the load is also transmitted from the side frames to the Journal bearings by means of springs, in this instance comprising helical springs 69;

~3~7~

and it will be noted that clearance is again provided in the pedestal jaws so that the yaw and other relative angular motions may occur without undesirable restriction. It should also be understood that with the stronger steering arms, the springs could be located alongside the axle boxes and the weight could be carried from the springs to the bearing boxes through the steering arms.

In this second embodiment, the interconnection between the steering arms takes a different structural form which permits using the space in the center of the truck for secondary suspension parts such as leaf springs or for other purposes. However, as in the first form, the inter-connection means provides freedom for relative pivotal motion of the steering arms and thus of the wheel sets in the yawing sense, but instead of employing a centrally located ball or pivot joint, the two steering arms are pivotal interconnected with a centrally located inter-mediate member or plate 700 Each steering arm 66 is con-netted with the plate 70 by a pivot joint diagrammatically indicated at 71. The plate 70 is suspended from the main truck framing by means of upright connecting rods 72. These rods have flexible joints 73 at their upper ends suspending the rods from the main truck framing and further have flex-isle joints 74 at their lower ends connecting the rods with ~3~73L

the plate 70. Because of this arrangement, the connecting plate 70 has freedom for motion laterally in a horizontal plane. Yaw motion of the plate is prevented by the pair of guide rods 75. Thus, the relative motions of the steer-in arms which are connected with the plate by the flexible joints 71 are constrained in the same manner as would be the case if they were connected directly to one another as by a pivot joint 37 in the first embodiment.

In view of the arrangement just described, tree-lion forces are communicated from steering arms to the eon-trial plate 70. Those forces are, in turn, communicated to the main frame structure also by means of the rods 75, one disposed toward each side of the truck frame and being connected at one end by flexible joints 76 with brackets 77 which, in turn, are connected with the truck side frames.
The other ends of the rods 75 have flexible joints 73 servo in to connect the rods with the brackets 79 which are mounted on the plate 70. Thus, the plate 70 acts to interchange steering forces between the two steering arms and to carry traction forces from the steering arms to the truck frame.

Torque forces are communicated between the motor 27 and the steering arm of each wiliest by means of spaced abutment lugs 80, one projecting from the motor above the steering arm and tube other projecting from the motor below ~3~L7~

the steering arm, as shown in Figure 5. The torque forces are communicated to the plate 70 and from that plate through the links 72 to the rigid truck frame. It can be visualized that the motor could be supported entirely by extending the motor 27 in the region 87 and providing for connection to the steering arm cross member 82 mentioned horribly.

It is further contemplated to employ generally horizontal links 81 at opposite ends of the truck, each link providing for interconnection of the adjacent steer-in arm and the adjacent transom of the truck frame, the latter being indicated at 82. Flexible connections 83 and 84 at the ends of each link 81 are associated with brackets 85 and 86 which are mounted respectively on the adjacent steering arm 66 and on the adjacent transom 82.

Because of the links 81/ tube relative yawing motions of the two steering arms are accompanied by trays-verse motion of the interconnecting plate 70 with which the steering arms are joined by the flexible connections 71. This transverse motion is similar to that of pivot 37 in the first embodiment.

It is to be understood that a variety of car body/truck interconnections could be used with bolster means such as illustrated and described in connection with the first embody-mint are present in the event that the truck of Figures I .

5, 6 and 7 is being retrofitted to an existing truck struck lure, as referred to in Figures 1, 2, 3 and 4. Other parts and devices will, of course, also be used, including for example brakes arranged as described above in relation to Figures l to 4, but various of these additional parts are not shown and described in detail with reference to the embodiments of Figures 5, 6 and 7.

It will be noted that in Figures 5 and 7, certain distances are marked, being identified by the letters a and b. The distance a represents the spacing from the center of the axle to the point of connection 71 of the steering arm with the plate 70. This spacing should be the same for each of the two motorized wheel sets, but the spacing b between the pivot joints 71 for the two steering arms may be different from the spacing a and is not critical.
It is further noted that with distance b made approximately equal Jo pa, the embodiment can be used on a three-axle truck with the third motor/axle assembly moving laterally with plate 70.

CONCLUSION:
. . _ The foregoing description of the two embodiments shown in the drawings discloses novel arrangements for pro-voiding a self-steering function in multiple axle powered I

locomotive trucks. This results in greatly increased occur-cay of tracking of the wheels, with consequent extensive increase in wheel adhesion. This not only eliminates us-desirable wheel flange/rail forces on curved track and also virtually eliminates high-speed hunting, with the resultant excessive wear on both road bed and trucks, but in addition, these various improvements in the operation of the powered truck result in greatly increased traction available from a given input of power.

Claims (27)

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

1. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for yaw motion of the wheelset with respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wheel-set also having a drive motor mounted on its axle and mov-able in yaw with the wheelset, a steering arm associated with each wheelset, each wheelset with its motor and steer-ing arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substan-tially equal and opposite pivotal yawing motion of the wheel-sets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial posi-tions when travelling on curved track, and flexible connec-tion means interconnecting the steering arm for each wheel-set with the truck frame in a region offset from said pivot means beyond the axle of that wheelset and restraining rela-tive lateral motion of the truck frame and the steering arm in said offset region, while permitting yaw motions of the steering arm.

2. A construction according to Claim 1 in which said last means comprises, for each steering arm, a link extended generally transversely of the truck, with one end flexibly connected with the steering arm and the other end flexibly connected with the truck frame.

3. A construction according to Claim 2 in which the connection of the link with the steering arm and with the truck frame includes a flexible joint.

4. A construction according to Claim 1 in which the pivot means interconnecting the steering arms provides for relative pivotal motion of said arms in a direction accommodating symmetrical relative yaw and pitching motions of the wheelsets and also in a direction accommodating rela-tive roll motion of the wheelsets.

5. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for yaw motion of the wheelset with respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wheel-set also having a drive motor mounted on its axle and mov-able in yaw with the wheelset, a steering arm associated with each wheelset, the wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substan-tially equal and opposite pivotal yawing motion of the wheel-sets of said pair independently of the truck frame and there-by cause both of the wheelsets to assume radial positions when travelling on curved track, and, for each steering arm, means associated with the steering arm and the truck frame including abutment surfaces positioned to communi-cate traction forces between the steering arm and the truck frame.

6. A powered railway truck comprising load-carry-ing framing, a pair of axled wheelsets each having journal bearings mounted to support the truck framing and having clearance providing freedom for yaw motion of the wheel-set with respect to the truck frame, resilient load-trans-mitting means between the journal bearings and the framing, each wheelset also having a drive motor mounted on its axle and movable in yaw with the wheelset, a steering arm asso-ciated with each wheelset, each wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to as-sume radial positions when travelling on curved track, means for communicating the traction forces from the steering arms to the truck framing, and spring means for delivering load from the framing to the wheelsets, said spring means having sufficient yaw flexibility to substantially avoid communication of traction forces from the wheelsets through the spring means to the truck framing.

7. A construction according to Claim 6 in which the framing includes side frame elements and further includ-ing at least one transom extending transversely between the side frame elements of the truck, the construction further including means for transferring motor torque re-action from at least one wheelset to said transom independ-ently of the steering arm.

8. A construction according to Claim 6 and further including means interconnecting the steering arms and pro-viding for concurrent equal and opposite pitching motions of the steering arms and also for the exchange of pitching torques between the two steering arms.

9. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for yaw motion of the wheelset with respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wheel-set also having a drive motor mounted on its axle and mov-able in yaw with the wheelset, a steering arm associated with each wheelset, each wheelset with its motor and steer-ing arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substan-tially equal and opposite pivotal yawing motion of the wheel-sets of said pair independently of the truck frame and there-by cause both of the wheelsets to assume radial positions when travelling on curved track, and for each wheelset, separate brake mechanism comprising brake shoes for the two wheels of that wheelset, a common brake cylinder for said brake shoes, and brake levers interconnecting said shoes and the brake cylinder and providing for equalization of brake-applying force to the wheels of that wheelset in-dependently of the brake-applying force of the brake mech-anism for the other wheelset.

10. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for yaw motion of the wheelset with respect to the truck frame, each wheelset also having a drive motor mounted on its axle and movable in yaw with the wheelset, a steering arm associated with each wheelset, each wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and oppo-site pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial positions when travel-ling on curved track, the truck having side frame members and having a transverse frame member extended between the side frame members, and abutment means cooperating with the steering arms and with a transverse member extended between the side frame members for transmitting tractive effort from the steering arm to the transverse frame member and thus to the side frame members.

11. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for movement of each wheelset both laterally and longitudinally of the truck and also for rela-tive motion to various different positions in yaw, each wheelset also having a drive motor mounted on its axle and movable with the axle, a steering arm associated with each wheelset, the wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnect-ing the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial positions when travelling on curved track, and, for each steering arm, means associated with the steering arm and the truck frame including an abutment pad positioned to communicate traction forces between the steering arm and the truck frame, the abutment pad being formed to provide surface-to-surface contact, even in various different yaw positions of the steering arm with respect to the truck frame.

12. A construction according to Claim 11 and further including means interconnecting the steering arms and constructed to transmit traction forces from one steer-ing arm to the other steering arm, and in which the abutment pad for one steering arm is arranged to transmit traction forces to the truck frame in one longitudinal direction and the abutment pad for the other steering arm is arranged to transmit traction forces to the truck frame in the oppo-site longitudinal direction.

13. A construction according to Claim 11 in which each abutment pad is formed of a resilient material adapted to accommodate relative yaw motion of the steering arm with respect to the truck frame.

14. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having free-dom for yaw motion of the wheelset with respect to the truck frame, at least one wheelset also having a drive motor mounted on its axle and movable in yaw with the wheelset, a steering arm associated with each wheelset, the wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial positions when travelling on curved track, and for the wheelset having a drive motor, means providing for the transmission of torque reaction forces directly from the motor to the truck frame independently of the steering arm.

15. A construction according to Claim 14 and further including abutment means associated with the steer-ing arm for the motorized wheelset and with the truck frame for transmitting traction forces from the steering arm to the truck frame.

16. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clear-ance providing freedom for yaw motion of the wheelset with respect to the truck frame, at least one wheelset also hav-ing a drive motor mounted on its axle and movable in yaw with the wheelset, a steering arm associated with each wheel-set, the wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnect-ing the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial positions when travelling on curved track, and a sanding device for each motor driven wheel, the sanding device being mounted on the steering arm for the driven wheels.

17. A method for retrofitting a powered railroad truck with mechanism providing for wheelset steering, which method comprises:

a) selecting an existing truck having load-carrying side frame members with two pairs of pedestal jaws each with pedestal liners, two wheelsets each comprising a pair of wheels fixed on an axle having a driving motor and axle bear-ings and bearing adapters received in the pairs of pedestal jaws, the bearing adapters of each pair having load-carrying spring connection with the side frame members, b) removing at least a part of the ped-estal liners to provide increased freedom for yaw movement of one wheelset with respect to the other wheelset, c) applying a steering arm to each wheel-set, the steering arm being connected with the wheelsets to provide for conjoint movement of each wheelset with its steering arm in fixed relation in the yawing sense, d) establishing a pivotal interconnection of one steering arm to the other steering arm in a region offset from the axles in a direction between the wheelsets and thereby provide for coordinated pivotal motion of the wheelsets in the yawing sense and for coordinated interchange of steering forces between the wheelsets, e) and interconnecting the steering arms to the truck frame members by applying connection means in regions offset from the axles in a direc-tion longitudinally of the truck opposite to the direction of offset of the pivotal intercon-nection of the steering arm, said connection means serving to restrain relative lateral motion of the steering arms and truck frame members in said spaced regions and thereby provide for lateral displacement of said pivotal intercon-nection during coordinated pivotal motion of the wheelsets and steering arms.

18. A method as defined in Claim 17 in which the connection means between the steering arms and the truck frame members comprises a transversely extended link for each steering arm and each link being flexibly con-nected at opposite ends to a steering arm and to a truck frame member in said regions longitudinally offset from said pivotal interconnection.

19. A method for retrofitting a powered railroad truck with mechanism providing for wheelset steering which method comprises:

a) selecting an existing truck having side frame members, a bolster and transversely extended leaf springs for transmitting load to the side frame members, and with two pairs of pedestal jaws each with pedestal liners, two wheelsets each comprising a pair of wheels fixed on an axle having a driving motor and axle bear-ings and bearing adapters received in the pairs of pedestal jaws, the bearing adapters of each pair having load-carrying spring connection with the side frame members, b) removing at least a part of the ped-estal liners to provide increased freedom for yaw movement of one wheelset with respect to the other wheelset, c) replacing the leaf springs with rubber pads for transmitting load from the bolster to the side frame members, d) applying a steering arm to each wheel-set, the steering arms being connection with the wheelsets to provide for conjoint movement of each wheelset with its steering arm in fixed relation in the yawing sense, e) establishing a pivotal interconnection of one steering arm to the other steering arm in a region offset from the axles in a direction between the wheelsets and thereby providing for coordinated pivotal motion of the wheelsets in the yawing sense and for coordinated interchange of steering forces between the wheelsets, f) and interconnecting each steering arm to the truck frame by applying connection means in regions offset from the axles in a direction longitudinally of the truck opposite to the direc-tion of offset of the pivotal interconnection of the steering arms, said connection means serv-ing to restrain relative lateral motion of the steering arms and truck frame in said spaced regions and thereby provide for lateral displace-ment of said pivotal interconnection during coor-dinated pivotal motion of the wheelsets and steer-ing arms.

20. A method for retrofitting a powered railroad truck with mechanism providing for wheelset steering, which method comprises:

a) selecting an existing truck having load-carrying side frame members with two pairs of pedestal jaws each with pedestal liners, two wheelsets each comprising a pair of wheels fixed on an axle having a driving motor and axle bear-ings and bearing adapters received in the pairs of pedestal jaws, the bearing adapters of each pair having load-carrying spring connection with the side frame members, and further having brake mechanism including a brake cylinder at each side of the truck and brake-operating connections from each cylinder to the brakes for the two wheels at that side of the truck, b) removing at least a part of the ped-estal liners to provide increased freedom for yaw movement of one wheelset with respect to the other wheelset, c) applying a steering arm to each wheel-set, the steering arms being connected with the wheelsets to provide for conjoint movement of each wheelset with its steering arm in fixed relation in the yawing sense, d) establishing a pivotal interconnection of one steering arm to the other steering arm in a region offset from the axles in a direction between the wheelsets and thereby provide for coordinated pivotal motion of the wheelsets in the yawing sense and for coordinated interchange of steering forces between the wheelsets, e) and altering the brake-operating con-nections to provide for operating the brakes on the two wheels of one wheelset by one of the brake cylinders, and to provide for operating the brakes on the two wheels of the other wheel-set by the other brake cylinder.

21. A powered railway truck comprising a load-carrying frame, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clearance providing freedom for yaw motion of the wheel-set with respect to the truck frame, resilient load-trans-mitting means between the journal bearings and the frame, each wheelset also having a drive motor mounted on its axle and movable in yaw with the wheelset, a steering arm associated with each wheelset, each wheelset with its motor and steering arm being jointly movable in the yaw sense, and pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and including means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheelsets to assume radial positions when travelling on curved track, said means comprising an element intermediate the steering arms, pivots connecting the steering arms to said element independently of each other, and means enforcing substan-tially equal and opposite pivotal motion of the steering arms with respect to said element.

22. A construction as defined in Claim 21 and further including mechanism for mounting said element on the truck frame with freedom for movement of said element in a direction transversely of the truck.

23. A construction as defined in Claim 21 in which said pivots interchange traction forces through said intermediate element.

24. A construction as defined in Claim 23 and further including means for transmitting traction forces from said element to the truck frame.

25. A construction as defined in Claim 21 and further including, for each wheelset, means for transmit-ting torque forces from the motor to the steering arm.

26. A powered railway truck comprising side frame members and transoms interconnected to provide a load-car-rying truck frame structure, a pair of axled wheelsets each having journal bearings mounted to support the truck frame and having clearance providing freedom for yaw motion of the wheelset with respect to the truck frame, resilient load-transmitting means between the journal bearings and the frame, each wheelset also having a drive motor mounted on its axle and movable in yaw with the wheelset, a steer-ing arm associated with each wheelset, the wheelset with its motor and steering arm being jointly movable in the yaw sense, pivot means interconnecting the steering arms in the mid-region between the pair of wheelsets and includ-ing means enforcing substantially equal and opposite pivotal yawing motion of the wheelsets of said pair independently of the truck frame and thereby cause both of the wheel-sets to assume radial positions when travelling on curved track, and means for transmitting traction forces and motor torque forces from the steering arms to the truck frame regardless of the relative yaw positions of the wheelsets and steering arms.

27. A construction as defined in Claim 26 and further including, for each steering arm, a link extended generally transversely of the truck, with one end flexibly connected with the steering arm and the other end connected with the truck frame.