Patent Application
20220219740
The present disclosure generally relates to truck systems for railway cars. More specifically, the present disclosure relates to a steering arm assembly and related components for the railway truck systems of a railway car.
A rail vehicle (also referred to as a rail car) is a vehicle that is capable of traveling along the rails or tracks of a railway. Rail vehicles can include locomotives, freight cars, passenger cars, road-rail vehicles, and high speed trains, to name but a few examples. Rail vehicles generally include a rail truck (or trucks) and a vehicle body (or a car body), which may or may not be affixed to the trucks. The rail truck is a chassis or framework that allows the rail vehicle to travel forward or backward along the tracks of a railway. Rail trucks can include a variety of components, including a bolster, side frames, wheel sets (e.g., wheels and axles), and steering arms, and are used to support the car body and transmit and/or absorb loads between the car body and the rail. In one example of operation, a rail truck may include two wheel sets, each wheel set comprising an axle and two opposing wheels. One such truck may be located at the front of a rail car, and another may be located at the rear of the rail car, such that two wheel sets (or four wheels) support the front portion of the rail vehicle, and two wheel sets (or four wheels) support the rear portion of the rail vehicle.
Present trucks for railway vehicles have functional limitations that result from their method of manufacture. For example, many trucks are manufactured from casted components (i.e., components made via a casting process). Such cast trucks may not be able to achieve the dimensional reproducibility of a machined part. As a result of this imprecision in casting processes, the rail industry generally allows looser tolerances to be acceptable. In allowing such looser tolerances, the rail components tend to contribute to unpredictable performance and shorter product and component life.
Further, some rail trucks employ a steering mechanism to control the stiffness or flexibility between the wheel sets on the truck. That is, the steering mechanisms can help control how much movement can occur between the front and rear wheel sets on a particular truck. How the steering is controlled can be useful, depending on how the truck is intended to be used. For instance, some rail trucks may be used primarily on tracks that involve a relatively high level of turns (e.g., rail cars used in mining, or that may be intended for mountain travel). As such, these trucks may be configured with steering mechanisms that allow for more flexibility between the two wheel sets, which can reduce friction loads and other stresses as the rail car travels along turns. Alternatively, some rail trucks may be used primarily on straight track where they may travel at higher speeds. For such trucks, it may be desirable to employ a stiffer steering configuration to reduce hunting, vibrations, or other factors that can lead to frictional forces that can inhibit the straight-line traveling efficiency of the vehicle. However, while such steering mechanisms can be designed to be either stiff or flexible, such trucks are not readily adaptable. That is, a truck design that employs a stiff steering design cannot be readily adapted to accommodate a more flexible steering design and vice-versa.
The present application describes various features of a particular rail truck design that will be referred to as the advanced truck system (“ATS”), as well as its components, method of manufacture, and methods of use and operation. In one particular example, the present application describes a rail steering mechanism for use with the ATS (or other trucks) that is adaptable in terms of steering stiffness and flexibility. That is, the steering mechanism can be adapted to provide a stiffer steering configuration or a more flexible steering configuration without having to significantly modify the various other aspects and components of the ATS truck, or otherwise redesign significant aspects of the steering mechanism or truck assembly.
In some examples, the steering mechanism operates in connection with a rail truck that includes two side frames and two opposing wheel sets. The wheel sets are arranged so that, in a resting configuration, they are essentially parallel with one another, such that the four wheels of the rail truck are generally configured to travel in the same general direction. The steering mechanism is connectable to the truck, for example, via a bolted attachment at the roller bearing adapters of the truck.
In some forms, the steering mechanism includes two steering arms, which steering arms may have a V-shaped configuration (though other configurations can be used in other forms). In some examples, the steering arms are configured so that they can be fabricated, or formed via a machining process. Each steering arm includes a support with two braces that extend from a center vertex toward opposing side frames at one end of the truck. The two steering arms have joining components that are configured to connect together at a central articulation point of the steering mechanism. The joining components may be positioned at or around the vertex that forms the V-shape for each of the steering arms, for example. The two steering arms can connect to one another via a bolted arrangement, such that the connection involves aligning the two connection points, and passing a bolt or other articulation mechanism through the two joining components, thereby allowing each steering arm to be an extension of the other.
As noted, each of the steering arms includes a joining component. In some cases, the joining components can form respective male and female connector components, such that the steering arm having the male connector component is configured to install into the female connector component of the opposing steering arm. However, in other cases, the joining component for each of the steering arms includes a female connector, such as a cup-shaped connector component, that is configured to receive an insert. In this manner, the steering arms may be similar, or even identical (or virtually identical) to one another. The insert can include opposing sides, each having a flexible and/or elastomeric component that is configured to fit within the cup-shaped connectors of the steering arms. The insert (or the sides of the insert) may have a conical shape, and can provide a degree of flexibility or stiffness at the articulation point. The degree of flexibility can vary and depend on the flexibility of the insert, in particular, the flexibility of the flexible material that forms the portion of the insert that installs into the cup-shaped connector component. As such, a truck manufacturer can select a particular insert to meet the particular desired properties for the truck. That is, where the truck is to be designed for use on generally straight track such that stiffer steering properties are desired, then the insert can be selected to have a material that is generally of a stiffer nature. Alternatively, where the truck is designed to be more efficient around tighter turns such that a more flexible steering mechanism is desired, the insert can be selected from softer, or more flexible materials.
This application also relates to rail car trucks that utilize the above described steering arms and steering mechanism, and some embodiments also relate to the rail vehicles that ride upon such rail trucks.
Fabrication of a truck and its components in an industry dominated by castings can provide several advantages. For example, machined components can provide precise and repeatable tolerances. These advantages will permit a controlled, stable and higher speed performance as well as extend component part life including wheel sets, damping systems and wear components. Further, fabrication of the truck reduces development time and production time. Part modification, prototyping and testing are greatly accelerated. Accordingly, the industry can benefit from a fabricated rail truck that is not limited by US foundry capacity. In particular, the industry can benefit from fabricated truck systems for railway cars that can meet new AAR standards, such as M-976 or Rule 88 of the AAR Office Manual as well as proposed rules that expand the scope of M-976.
By using a fabrication there is an assurance of material quality as well as abundant availability of production stock. High quality nonporous metal stock, porosity being an ongoing issue with cast parts, is readily available. A diverse amount of alternate materials is also available. Use of nonstandard steels, lighter in weight and stronger in physical properties can be considered as opportunities.
The rail industry can also benefit from a lighter freight car truck. Certain examples of the ATS fabricated truck can be as much as 1,500 pounds lighter than 3 piece cast trucks. This feature can reduce railcar weight by as much as 3,000 pounds, and is achieved by reducing plate size where appropriate and adding of lightening holes. The reduction in weight allows for diesel fuel savings and increased payloads.
The rail industry can also benefit from an improved railway truck, such as the ATS, that has a set of design features that work in concert to provide improved steering and handling characteristics, particularly beneficial for high speed operation, negotiating curves, reducing hunting and in extending wheel and rail life. Specific design ranges can be determined as optimal, such as plate thickness, angles of attack and distances between functional parts.
The rail industry can also benefit from a steering truck like the ATS. Steering arms have a connection to each axle, via a bearing adapter, with a resilient component between the opposing steering arms that provide equal and opposite yawing movements. The current design with a cylindrical spring enclosed under compression in a metal sleeve can be modified, altered or changed to improve performance. Torque can be applied to the installed part, dimensions of the part can be optimized, and preferred material choices can be selected. New designs involving rubber blocks replacing the cylindrical spring may also provide steering advantages.
Current cast side frames strive to be rigid to reduce hunting, however this worsens curving, twist and roll, and pitch and bounce. Accordingly, the rail industry can benefit from a non-rigid side frame (e.g., as employed in examples of the ATS) that disassociates the two side frames from each other allowing free and independent movement which imparts improved performance on M-976 related tests. Transverse arms of a steering mechanism, described below, may extend between the side frames. An optimal width between these transverse arms could provide improved or even ideal performance.
The rail industry can also benefit from an improved non-linear damping system like that of the ATS, which can be custom designed for specific rail service. Inhibiting, reducing, and/or eliminating unpredictable friction damping, can help limit and/or minimize the impacts of associated metal springs going solid, and can allow for a smoother more controlled ride. Specifically tuned hydraulics and precisely designed elastomeric damping springs can replace metal springs and unpredictable friction damping. Optimal damping can provide improved or even ideal performance in the ATS.
Coupler height is established in the AAR's MSRP's. The ATS transom side frame platform holding the polymer spring, on which the bolster rides, can be designed to set higher or lower depending on the need of the user. Components can also be designed to retrofit already cut side frames.
Some examples of the ATS include a removable device to capture the steering arms. In existing trucks, the steering arms are typically disassembled before being removed from the truck. By making this configuration accessible, the ATS improves ease of assembly and repair.
A further advantage of the ATS includes the use of removable pins to capture the brake beam which allows for easy installation and removal. This is made possible due to the ATS truck brake rigging system being located outboard of the wheels. The brake system may also include brakes that hang and are applied in tension as opposed to compression. This may help to solve an industry hot issue of asymmetric wheel wear.
Some embodiments of the ATS include wear components found on various locations of the truck. These parts can be made with specific and optimal dimensions and be designed to solely work within our fabrication. For example, a replaceable pad between the side frame and the bolster, not found on the original fabricated truck can be employed. There is also a polymer sleeve on the transverse side frames plug which is inserted into its opposing side frame, the material and physical properties of which can be selected to provide advantages or desired functionality. These and other advantages can be achieved by various embodiments of the ATS.
In some examples, the ATS incorporates inboard bearings, resilient nonmetallic secondary springs, dissociated side frames, steering arms, and a stamped bolster. In some embodiments, the ATS incorporates all of the design features described herein into an inboard bearing fabricated truck, and the design features are believed to have a synergistic effect that enables the truck to meet or exceed recent AAR standards, such as M-976 for railcars having a 286,000 lb. gross rail load rating.
The ATS may include various additional features that offer improvements over other truck systems. Some of these features are described below.
Bolster location above side frames—The ATS, in some examples, has a bolster that is positioned above the side frames. Other three piece trucks, including those that have received M-976 approval, have the bolster located lower than the top of the side frames and engaged in the side frame opening. Even the new trucks that are part of the AAR Improved Freight Car Truck Strategic Research Initiative (SRI) have their bolsters located lower than the top of the side frames like other three-piece trucks. With a bolster lower than the top of the side frames, it can be difficult to locate the steering arms under the bolster as they are now located on the ATS truck. It is also difficult to maintain the body centerplate engagement with the ATS bolster should it be lowered significantly and still keep the coupler height on existing freight cars within the required range. This feature can also facilitate locating the steering arms under the bolster as described in more detail below.
Low friction interface supporting vertical load of freight car body located approximately at the position of a standard side bearing which is 25 inches laterally from centerline of car—Trucks often support the vertical load of the car body via the centerplate. However, in some aspects, the ATS supports the load of the freight car body at the standard side bearing location. This location for the vertical load support makes the ATS truck easy to retrofit to existing freight cars just as it was for the test cars at the Association of American Railroads Transportation Technology Center in Pueblo, Colo. (TTCI). The fact that the vertical load has a direct path from the car body interface, through the spring, and directly to the side frame could be considered significant as it brings up the inboard location of the roller bearings.
Special elastomeric damping spring secondary suspension—Certain embodiments of the ATS employ an elastomeric damping spring that is configured to provide a specific force deflection configured to operate in connection with the other features of the ATS.
Side frame—The side frames of the ATS can be formed from 3-inch-thick steel plate. The shape of the side frames can be seen in FIGS. 1-8 of the '733 provisional, and is discussed throughout the '733 provisional and its appendices. In some aspects, the shape of the side frames is configured to lighten the overall weight of the truck. The side frames can be fabricated from plate steel, but in some forms can also be formed via casting or a combination of fabrication and casting. In one embodiment, the design of the side frames is configured to take advantage of modern manufacturing capabilities where very accurate design dimensions can be maintained. The side frames may include transverse members that control the rotation of the side frames along their axes parallel to the longitudinal centerline of the freight car while allowing rotation of the side frames along their axes transverse to the centerline of the freight car. This transverse rotation can help allow the ATS truck to negotiate less than optimum track geometry. In some examples, the ends of the transverse members are welded to each side frame and enter a hole in the opposite side frame with a fit controlled by a nonmetallic bushing.
Side frame transverse arms—Some examples of the ATS include transverse arms that are welded to one side frame and connect to the opposite side frame with via a unique connection, as shown in FIGS. 1-8 of the '733 provisional, and described herein. The transverse arms can be used to stabilize the side frames from rocking on the adapters. The transverse arms can be connected in a “loose” manner to the opposite side frame to facilitate the side frames rotating independently of each other making it possible to negotiate rough track. Wheel load equalization tests performed at the TTCI include data related to this performance.
Primary suspension—The ATS includes a primary suspension that relates to the interface between the side frame and roller bearing adapter. The primary suspension includes an elastomeric damping and sliding feature. The primary suspension, in some examples, is retained in place by a cylindrical boss fitted into a cylindrical cavity in the pedestal roof of the side frame. Other embodiments include dropping the sliding feature so as to eliminate any dependency on friction which is hard to control. Also, the elastomeric material of the original design can take on a variety of forms to allow for movement of the axles relative to the side frames and to each other allowing them to assume an essentially radial geometry when the ATS truck is negotiating curves.
Steering arms—Certain aspects relating to the steering arms of the ATS, including how the steering arms attach to the inboard side of the roller bearing adapters and their location under the bolster, are shown in FIGS. 1-8 of the '733 provisional, and further discussed throughout this application and its appendices. The details concerning how the two portions of the steering arms are attached to each other have yielded very good results obtained during curve resistance tests. This application also describes more details regarding certain embodiments of a steering mechanism that includes multiple steering arms, and in particular, the connection between the multiple steering arms.
Roller bearing adapters—Some examples of the ATS include rolling bearing adapters that utilize a sliding interface with the primary suspension. In some embodiments, the roller bearing adapters can have a flat upper surface that interfaces with the primary suspension. The primary suspension can be installed on the roller bearing seat of the axle similar to a standard roller bearing, except that the roller bearing seat is located inboard of the wheels rather than outboard as is the case for the standard wheel set.
Roller bearing—In some examples, the ATS utilizes roller bearings. The roller bearings can be utilized in connection with an inboard connection of the steering arms and can be configured to a specific size based on the intended application.
Wheel sets—The ATS includes wheels and axles that may have different sizes of bores and wheel seat dimensions compared to standard wheel sets, as demonstrated in
Brake rigging—Some examples of the ATS operate with a tension based connection between brake beams. Given the tension connection and the fact that the brake beams of the ATS truck are of the hanger type, the ATS brake rigging can be used to address the asymmetric wheel wear problem that exists for other three-piece outboard roller bearing trucks with the compression connection between brake beams. The ATS truck is configured to provide improved access to the brake shoes by locating the brake beams and brake shoes outboard of the wheels of the truck, which makes these components easily accessible given that the side frames are not in the way.
Method of manufacturing—The present disclosure also presents methods for making the components of the ATS, for example, the bolster and side frame components. In some examples, the ATS components are fabricated and employ unique techniques not applied to other freight car truck systems, as described throughout this application and its appendices.
Interface between the car body and the truck bolster—The interface between the car body and the ATS truck bolster exists, in some forms, at the standard side bearing spacing for freight cars in the North American interchange system, which is about at 25 inches laterally from the centerline of the rail car. As a result, the interface utilizes a vertical load adapter made up of a series of plates. The plates may have a pair of holes in alignment with each other and the holes on the body bolster of the freight car body. These holes allow for bolts which attach the vertical load adapter to the body bolster and provide for a simple and nearly universal way to adapt or retrofit the ATS truck to virtually any new or existing rail car. The base plate of the vertical load adapter rests on a nonmetallic plate of the truck bolster and has a length and width that covers the entire surface of the nonmetallic plate. Thus the contact stress between the vertical load adapter and the nonmetallic plate can be reduced such that the body bolster of the car body and the truck bolster can rotate relative to each other with relatively low levels of resistance, or at least with a controlled resistance based on the coefficient of friction of the nonmetallic material
Interface between the body centerplate of the rail car—In some examples, this interface includes a ring at the centerline of the truck bolster that aligns with the body centerplate such that a standard body centerplate can be utilized. This can help simplify the retrofit to existing freight cars. Since the vertical loads are carried at the vertical load adapter, the body centerplate may carry no, or virtually no, vertical load. The interface between the truck bolster ring and the body centerplate also provides for the transfer of longitudinal and lateral loads that result from pulling and pushing the freight car in service and from braking of the freight car. That no (or essentially no) vertical loads are carried at the centerline of the truck bolster in some examples allows for a lightweight truck bolster design compared to a standard three-piece truck.
Secondary suspension—In some examples, the secondary suspension of the ATS truck includes an elastomer spring and a hydraulic damper. The elastomer or rubber spring is mounted between the truck bolster and side frame such that the load from the car body is transmitted directly into the side frame with no, or at least very little, eccentricity. The elastomer or polymer spring can be mounted in a range of from completely vertical to a slight inward angle of several degrees. A slight inward angle provides both vertical and lateral reaction forces helping to balance and stabilize the load from the car body. The elastomer spring also provides damping through the hysteretic energy absorption that is inherent in the material. The elastomer or rubber spring can take on a variety of different forms or embodiments. In one embodiment, the spring can use a Hytrel® type synthetic material processed in such a way as to provide optimized load and damping characteristics. In another, the spring can comprise a natural rubber material molded into a multi-layered spring with steel plates existing between the layers. In either embodiment, the property of the springs can be optimized for the application of the ATS to typical freight cars. In some examples, the hydraulic dampers, two per truck, can be mounted between the truck bolster and side frame at an angle such that, as with the secondary spring, damping is provided mainly in the vertical direction but with a significant component laterally. The characteristics of both the secondary spring and the hydraulic damper can be determined through dynamic numerical analysis in order to provide optimum truck performance for a variety of service conditions and to meet test criteria of the railroad industry.
As noted above, certain aspects of the present application relate to the details of a steering mechanism assembly that can be used in connection with a rail car truck (e.g., the ATS). The examples of a steering mechanism described herein may improve the performance of the rail truck in terms of the ability to reduce the rolling resistance of the rail truck as it travels around bends or turns. Moreover, the described mechanism also may maintain efficient operation on straight or tangential track, such that the ability of the steering arm to flex on turns does not negatively impact wobble or vibration levels as a rail car travels at higher speeds along straightaways.
Further, the described steering mechanism provides adaptability to the users and/or the manufacturers of the rail car trucks, such that individual trucks can be built according to particular flexibility standards without involving major structural or design changes in the truck or the steering mechanism. That is to say, one truck can be manufactured to have stiffer parameters and another truck can be manufactured to have more flexible parameters simply by modifying out one part, an insert (or in some cases, a male connector), without changing or modifying or changing the other components of the steering mechanism or truck assembly. In this way, manufacturers can save time and expense by utilizing one truck design that will adapt to a variety of customer demands. That is, the manufacturing and design process can be repeatable for a variety of different trucks, with the only difference being the specific insert that is used in the connection.
The first wheel set 40 toward the first side 14 of the truck 10 includes an axle 42 and two wheels 44/46 on opposite sides of the axle. The wheels 44/46 are configured to travel and move the truck along the rails of a railway. The first wheel set 40 may also include roller bearings 45/47 that facilitate rotation of the axle 42 and wheels 44/46 relative to the truck 10. The roller bearings 45/47 may include adapters that facilitate attachment to other components of the truck 10, such as the steering mechanism 100. On the second side 16 of the truck 10, the second wheel set 50 has a similar, even identical configuration, including an axle 52 and two wheels 54/56 and roller bearings 55/57 toward the second side 16 of the truck 10.
The two wheels 44/46 and 54/56 of the two wheel sets 40/50 are linked so that they are essentially parallel to one another at all times. Accordingly, as the truck 10 travels along a curved track, the treads of the wheels 44/46 may experience resistance in the form of friction as they rotate in a direction that is not parallel with the rails themselves. Accordingly, the steering mechanism 100 is configured to allow the two wheel sets 40/50 to rotate, or yaw (e.g., rotate about a vertical axis of the truck 10) relative to one another so that the wheels can align closer to parallel with the rails, thereby reducing the rolling resistance of the truck 10. This ability to allow yawing rotation is accommodated by way of a connection point at or around the center 18 of the truck 10 that attaches two steering arms of the steering mechanism assembly 100. In some forms, the steering mechanism 100 also allows freedom of movement and rotation in other dimensions (e.g., vertical rotation about an axis parallel with the wheel sets), which can also provide tangible benefits to the operation of the truck assembly.
It should be appreciated that the truck 10 shown in
In one example, the truck assembly may include brake beams that attach to the truck assembly outboard of the wheel sets 40/50, relative to the center 18 of the truck. For example,
As noted, the steering assembly 100 allows the wheel sets of the truck to yaw with respect to one another so that the wheels of each wheel set can remain generally parallel (or close to parallel) with the tangent of the track as the track curves. This ability to steer is allowed by way of a two-piece nature of the steering mechanism 100, and the particular point of connection between the two pieces.
The steering arms 110/130 are shown arranged in a V-shaped configuration, such that each steering arm has a pair of support arms that extend at an angle from a toward respective arm ends that attach to the wheel sets of the truck 10. While this V-shaped configuration represents one example, it is contemplated that other configurations of the steering mechanism could also be employed, provided that the steering arms have a central articulation point 190 that allows the steering arm to connect with another steering arm in a manner consistent with the examples described herein. For instance, the steering arms may take on a C or U-shaped configuration.
The steering arms 110/130 have respective joining components 120/140 that facilitate the connection between the two arms of the steering mechanism 100. The joining components are situated at or about the vertex of each of the V-shaped steering arms, and arranged to face the opposing joining component of the opposing steering arm. An articulation mechanism 160, which can be, for example, a nut/bolt assembly, a clamp, or similar device, articulates or connects the two steering arms 110/130 at the connection point.
The first steering arm 110 includes two separate support arms 114 and 116 that form a V-shaped configuration that converges at a vertex 112. Each support arm 114/116 extends away from the vertex 112 at an angle, towards respective arm ends 115/117 at the first side 102 of the steering mechanism 100. Likewise, the second steering arm 130 includes two separate support arms 134 and 136 that form a V-shaped configuration that converges at a vertex 132. Each support arm 134/136 extends away from the vertex 132 at an angle, toward respective arm ends 135/137 at the second side 104 of the steering mechanism 100. As noted above, the arm ends 115/117 and 135/137 can be used as linkages that allow for brake beams to attach to the truck outboard of the wheel sets.
The joining components articulate the two steering arms in a manner that allows a separation space 180 between the two arms. This separation space 180 or clearance allows the two steering arms 110/130 of the steering mechanism to rotate relative to one another, thereby limiting rolling resistance when the truck passes along curved rail track. The separation 180 is configured to allow a controlled amount of rotation, but not so much that the steering mechanism becomes unstable such that the truck will wobble, vibrate, or face hunting issues that can inhibit the efficiency of the vehicle, particularly as it travels on straight track and/or at high speeds. For instance, the separation 180 can be sufficient to meet the hunting requirements of AAR Specification M-976 and Chapter 11 of the AAR Manual of Standards and Recommended Practices, which hunting requirements include that the truck be tested under an empty test car and that at 70 mph the lateral acceleration of the car is not to exceed 1.5 g's peak to peak with a maximum standard deviation of 0.13 (hereinafter “the AAR hunting requirements”). This separation 180 allows the steering arms to follow the geometry of the rail as the truck negotiates curved track. The separation can vary depending on the particular needs and designs of the steering mechanism 100 and the truck. In one example, the separation 180 may be less than about one inch. More particularly, the separation 180 may be between about ⅛ of an inch and ⅜ of an inch. Even more particularly, in some examples, the separation may be about ¼ of an inch. The separation is maintained by way of an insert that is positioned between the two joining components 120/140.
The insert is shown in more detail in
While this conical shape is suitable in some situations, it is contemplated that variations on the shape may also be employed. For instance, the insert may have a spherical shape, or a 3-dimensional elliptical shape, such as a prolate spheroid (i.e., a football shape), an egg shape, or other shapes, provided that the insert is adapted to mate with the recesses of the joining components 120/140 of the steering arms 110/130. The insert 150 also includes a central opening 158, or a tunnel that is configured to receive the articulation mechanism 160 (e.g., a bolt or pin) that passes through the joining mechanisms.
The insert 150 includes a base 156, which can be formed from a rigid material, such as steel or other metals, and can take on a segmented cylindrical shape, as shown in
The type and flexibility of the flexible material 153 can vary depending on the desired functionality of the steering mechanism 100. For example, where stiffer steering control is desired (e.g., where the steering mechanism is to be used on rail cars that will predominantly travel at high speeds on straight track), than a flexible material 153 can be selected to have stiffer properties. Conversely, where more flexible steering control is desired (e.g., where the steering mechanism is to be used on rail cars that intend to negotiate frequent or significant curves), a softer or more flexible material 153 can be selected. In this way, the flexible material 153 may be the only component of a truck that differs from truck to truck, while still providing adaptability that allows a truck manufacture to adapt a steering control level based on the intended use.
Because the material on the first and second sides of the insert 150 is flexible, the insert will be able to deflect in response to a rotational force or moment being applied about the articulation point 190. The amount of deflection will depend, at least in part, on the stiffness/flexibility of the material. Depending on the amount of rotation that is desired, the material of the insert 150 can be selected to be more rigid or more flexible. In some situations, the insert is selected to have a flexibility level that is sufficiently stiff to inhibit hunting of a rail car truck traveling along a straight track, while at the same time being sufficiently flexible to inhibit rolling resistance of a rail car truck negotiating turns For example, the flexibility of the insert 150 can be sufficient to meet the AAR hunting requirements, while at the same time having a rolling resistance of 200 pounds or less, and in some cases 100 pounds or less, for up to 12 degrees of curvature.
It should be noted that the present Figures describe an embodiment that uses a removable insert to facilitate the connection, and in some situations the insert may be an extension of one of the steering arms. For example, the joining component of one steering arm may include a male mating component, such as a nose or extender protruding from the joining component as a male connector, which connector may take on a shape and configuration similar to one side of the insert 150. That is, the male connector may have a conical shape and comprise a flexible material. The joining component of the opposing steering arm may include a corresponding female mating component, such as a recess similar to those described with respect to the Figures. In such a situation, the steering arms can connect in a similar fashion to that described with respect to
The present application also presents methods for assembling a steering arm assembly for a rail car.
The method 700 includes selecting 710 an insert having a conical shape. As described herein, a “conical” shape means that the insert has segments that form portions of cones or conical structures. For instance, the insert may take on the shapes of the insert 150 shown in
The selected insert is then mated with a corresponding mating component on a first steering arm. This mating 720 can involve placing the first side of the insert into a recess on a joining component of a first steering arm. The steering arm may include a pair of support arms arranged in a V-shaped configuration extending away from the joining component, such as the steering arms 110 and 130 described herein.
The selected insert also mates with a corresponding mating structure on a second steering arm. For example, the mating 740 may include placing the second side of the insert into a recess on a joining component of the second steering arm. The second steering arm may be identical to the first steering arm, or it can take on a different structure, depending on the structure of the rail truck that the steering mechanism will be used on.
Next, the two joining components of the steering mechanism are articulated together. The articulation can involve passing a bolt 740 through the first and second joining components so the bolt passing through a central opening in the insert, so that a head of the bolt abuts one of the joining components and so that a portion of the bolt extends beyond the other of the joining components, and subsequently applying 750 a clamping component to the portion of the bolt that extends beyond the other of the joining components to clamp the first and second steering arms together. In other examples, the clamping can take on other forms, and may involve other equipment different from a nut and bolt assembly.
Upon performing the clamping, the first and second joining components will be separated by a minimum distance by way of the insert. That is, the insert (and the corresponding mating structures of the steering arms) will be configured so that, when fully clamped, the insert maintains a separation between the two steering arms. This separation allows the first and second steering arms to rotate relative to one another, such that the rotation will not be thwarted or obstructed by way of contact with an opposing steering arm. This rotation can be a yaw rotation, that is, a rotation in a plane parallel to the steering mechanism (i.e., a plane parallel to the tracks on which the rail car truck will travel). However, the assembled steering mechanism can be configured to control motion and rotation among all six degrees of freedom, via the insert and the use of other articulation devices. The insert is configured to provide resistance to the relative rotation between the first and second steering arm, and the flexibility of the insert, namely the flexible material that is part of the insert, will at least partly affect the ability of the insert to resist the rotation. As such, selecting a particular insert will allow a manufacturer to control, at least partially, the stiffness of the steering mechanism. In some examples, the method 700 can also include further installing the assembled steering mechanism to a rail car truck. For example, the installing can include connecting each of the support arms of the individual steering arms to a roller bearing adapter associated with a wheel set of the rail car truck.
The method 700 can be repeatable for the assembly of multiple steering mechanisms, such that different steering mechanisms can be produced using the same, or essentially the same process, with the only difference being which insert is selected. By selecting different inserts, manufacturers can easily produce steering mechanisms having different stiffness properties without having to overhaul, or even significantly modify any major aspect of the assembly or manufacturing process. In one particular example, shown in
Various aspects, features, and examples of steering mechanism, and in particular, of a connection or articulation point for a multi-arm steering mechanism, have been described. Such steering arms offer tangible benefits and improvements when implemented on rail car trucks. For example, the steering mechanisms can cause the wheel sets of a truck to assume a radial position (or close thereto) while a rail car is negotiating a curve or turn. By arranging the wheel sets in a radial position, the steering arm thus helps avoid or inhibit detrimental forces that can otherwise arise between the wheel flanges and the rail in the curve. This can reduce wear on both the wheel and rail, thus providing significant benefits to both the owner of the rail car that is responsible for maintenance of the wheels, and the owner of the railroad track itself. Moreover, the steering mechanism also helps reduce resistance to trains traveling around curves. Curving resistance testing was conducted at the TTCI during testing, and the test results showed that the curving resistance of the ATS truck employing steering mechanisms in accordance with the above disclosure was much lower than the common three-piece truck in service on many freight cars operating in interchange service in North America. The results of such testing is shown in
Another benefit of the steering mechanism is that it helps to square off the two wheel sets while the truck is negotiating a straight or tangent track. That is, the steering mechanism helps assure that the wheel sets of a truck are essentially parallel when the track itself is straight. Squaring the wheel sets helps inhibit track hunting, thereby improving the performance of the rail car at high speeds. It also inhibits lateral oscillations among the wheel sets, which improves performance under the normal speeds of operation.
The steering mechanism described herein can be formed from fabricated steering arms, which allows for a lighter weight construction. The weight of the ATS steering mechanism can be formed to be 400 pounds or less, which is lighter than other steering mechanisms. In some forms, the weight of the entire steering mechanism can be formed to be 200 pounds or less. In some forms, the outer ends of the V-shaped steering arms can be bolted directly to the roller bearing adapters of the truck. This direct connection to the adapters, which thereby forms a direct connection to the wheel sets, allows the steering mechanism to directly control the geometry of the two wheel sets relative to each other. For instance, if the lead wheel set of the truck enters a curve and rotates or takes on an angle of yaw relative to the truck side frames and the freight car body, the trailing wheel set will rotate in an opposed yawing movement. The exact amount of rotation or yawing is generated by the wheel rail geometry and the stiffness of the insert installed between the two steering arms. It has been found from testing at the TTCI that the ATS steering mechanism described herein results in significantly reduced rolling resistance compared to other current trucks operating in the North American Interchange System.
In
Another observation made during the rolling resistance testing was that a rail contact mark or ring on the tread of the wheels on the ATS trucks was centered on the tread over a band of about 1 to 1½ inches wide. This is shown on the wheel depicted in the photograph of
Because the steering mechanism employs an insert that inserts into both steering arms, the steering mechanism is able to maintain a relatively straight alignment among the wheel sets during operation on a straight track. This is due, in part, to the rigidity of the steering mechanism, and its ability to span between, and enter into the respective steering arms. This configuration establishes a link that inhibits unwanted sway on a straight track. However, because the insert also comprises flexible material on the portion that inserts in to the recesses of the steering arms, when a rotational moment or force is applied to the insert (e.g., when the truck travels along a curve), the flexibility of the material allows some leniency, and thus allows the steering arms to momentarily rotate relative to each other so that the wheel sets can remain essentially parallel with the rail tracks. In some situations, this ability to allow rotation can also be facilitated, at least in part, by the shapes of the insert and recesses of the joining components. For instance, utilizing a conical shaped insert and corresponding shape for the inserts allows relatively even freedom of rotation about the connection point.
Another capability of the ATS Steering Truck concerns the ability to tune the truck for different operating conditions. Because, at least in some examples, the insert is a separate component from the steering arms—that is, it is removable from the steering arms because it is not an extension there to, the steering arms can be adaptably assembled to cover a variety of different stiffness values and to meet a variety of different steering objectives. In other words, a steering arm manufacturer can make different steering mechanisms, on demand, that have different stiffness values without having to significantly alter the manufacturing process and without having to obtain different steering mechanism components (aside from the different inserts). The properties flexible material (e.g., a polymer piece) in the central connection between the two steering arms can be optimized, for example, using a dynamic numerical analysis. In this way, users of the ATS steering mechanism may be able to fine tune the steering stiffness to achieve particular performance characteristics when one regime of performance is emphasized over another based on a particular numerical analysis. Therefore, the ATS Steering Truck includes the potential to tune the truck for specific service conditions.
Yet another benefit of the presently described steering arms relates to the ability of the truck to distribute load as a result of the conical shape of the connection between the steering arms (whether the connection is formed with an insert and two female connectors or with a male/female connector relationship). The conical shape of the central connection also allows for motion of the wheel sets where one wheel may be raised or lowered without unduly causing a detrimental reduction in vertical wheel load on any of the other wheels. Tests were conducted at the Transportation Technology Center where this capability was explicitly determined.
The results of raising and lowering one wheel, the L1 wheel, is shown in
Another benefit of some of the described steering mechanism examples is that the brake beams are attached through a linkage at the ends of the V-shaped steering arms such that the brake beams are located outboard of the wheels relative to the center of the truck. Each brake beam has a brake head at each lateral end that has a brake shoe engaged to it during normal operation. Because the steering arms move in alignment with the wheel sets, the brake beams and brake shoes are kept in alignment with the wheel treads. Brake beams on the standard 3-piece truck are located inboard of the wheels and are supported by cast in pockets on the side frames. Because the side frames of a standard 3-piece truck do not move in alignment with the wheel sets, the brake beams shift sideways relative to the wheel treads during operation. Also, the connection between the brake beams of the ATS truck can employ a tension connection, which can help keep the brake shoes aligned with the wheel sets. The connection between the brake beams of a standard 3-piece truck is utilizes compression members (as opposed to tension), which forces the brake beams laterally relative to the wheel sets. The lateral movement of brake beams on a standard 3-piece truck results in an asymmetric wheel wear condition as the brake shoes contact the wheel flanges of diagonally opposite wheels. This asymmetric wheel wear can be inhibited by the brake beam arrangement described above for the ATS truck.
The ATS Truck
In addition to the steering assembly, the ATS truck includes a variety of other features, components, and modes of operation. Certain examples of such features will now be described. It should be understood, however, that these specific examples should not be considered to limit the scope of the present disclosure, or any of the other examples described in this application.
In one example, the ATS truck includes freight car truck with two wheel sets, each consisting of axles, wheels, and roller bearings within pedestals of two side frames of the truck. The wheels can be spaced on the axles 53 inches apart, from inside to inside, such that they can operate on standard gauge rails at the common dimension of 4 ft. 8½ inches from gauge face to gauge face. The side frames can be located inboard of the wheels and include pedestals at the ends in which a roller bearing adapter is placed which sits on top of the roller bearing seat on the axle. The side frame pedestals are located longitudinally from each other to maintain a nominal axle/wheel spacing of about 70 inches. This spacing can vary by simply changing that dimension on the side frame, in particular, with this spacing can be changed relatively easily where the components are formed via a fabrication process. The ATS truck includes an elastomeric sandwich pad between the bearing adapter and the side frame, which pad can have specific properties in the longitudinal and lateral directions configured so that some rotation of the axles and wheels is allowed relative to the side frames. The ATS truck also includes a truck bolster above the side frames and is supported by a secondary spring made of an elastomeric material. The bolster is attached to the side frames by two hydraulic dampers located at an angle configured to react both vertical and lateral loads. The two hydraulic dampers are also located at diagonally opposite corners of the bolster and side frame assembly. A steering arm assembly, separate from the vertical load bearing assembly just described, is connected to four roller bearing adapters of the truck using a bolted attachment. The steering arm assemblies are made up of two similar subassemblies that are attached together by a centrally located bolted arrangement. The bolted arrangement includes elastomeric components of with characteristics configured to improve the curving performance of the ATS truck while at the same time maintaining parallel alignment of the two wheel sets when negotiating tangent or straight track at high speed thus providing a sufficiently high hunting threshold speed as to provide superior hunting performance.
In some embodiments, freight car truck includes a vertical load adapter attached to the body bolster of a freight car body. The attachment is located about 25 inches laterally from the longitudinal centerline of the freight car, one attachment on each side of the car. The attachment can be bolted or welded to the body bolster. If it is bolted, the attachment can make use of the standard holes in the body bolster used for attaching a body side bearing wear plate and associated shims. The vertical load adapter includes a series of plates one located on top of the other. The bottom plate has a length essentially parallel to the longitudinal centerline of the freight car body. The length and width of the bottom plate are sufficient so as to cover the entire surface of the nonmetallic plate located on top of the ATS bolster. The edges of the bottom plate are contoured slightly so as to avoid scrapping the surface of the nonmetallic plate as the truck bolster rotates relative to the freight car body bolster. If a bolted attached is utilized, the bolt holes in the bottom plate are countersunk so that the head of the bolt shall be below the bottom surface of the bottom plate to avoid gouging the nonmetallic plate when the truck bolster rotates relative to the body bolster. A filling material may be used to make the finished surface above the head of the bolt smooth in its interface with the nonmetallic plate. The intermediate plates, of which there may be one or several, make up the vertical load adapter and have sufficient thickness to level the car body at their four locations while also providing an interface between the central ring of the truck bolster and the centerplate of the car body, with a clearance of about ¼ inch between the top of the central ring and the horizontal flange of the body centerplate or body centersill. The length and width of the intermediate plates may be less than the length and width of the bottom plate. The material for the plates of the vertical load adapter shall be made of a grade of steel that can support the vertical load of a fully loaded freight car body of at least 286,000 pounds, less the weight of the ATS trucks.
In some examples, the truck bolster of the ATS truck is of a lightweight design compared to a standard three-piece truck because no vertical load is carried at the central location where the truck bolster interfaces with the centerplate of the freight car body. The truck bolster can include a ring at its center having a diameter large enough to allow a body centerplate, with a diameter of 14 to 16 inches to be inserted without interference. The central ring has a clearance around its circumference with the body centerplate of approximately ¼ inch. The vertical surface of said central ring is high enough to engage the vertical surface of the body centerplate or about 1% inches. The truck bolster at this central ring interface may carry no vertical load. The bolster may also include a center pin assembly located within and below the central ring. The center pin can have a height and diameter that can be inserted in the central hole of the body centerplate when the car body is lowered onto the ATS truck. The center pin assembly can work as a guide for lowering the car body onto the truck and may not react any vertical, longitudinal, or lateral loads. The truck bolster may also include two nonmetallic plates located such that their longitudinal centerlines lie within 2 inches (plus or minus) of the 25 inch dimension of the side bearing location on a freight car. The nonmetallic plates can be attached to the top of the truck bolster via a variety of means, including bolted, bonded, or even loose in a sufficient frame. The length and width of the nonmetallic plates is such that as the truck bolster rotates up to 12 degrees relative to the body bolster of the freight car, the bottom plate of the vertical load adapter maintains a contact surface with the nonmetallic plate of at least 70% of its surface area.
In some examples, the freight car truck includes a secondary suspension spring located under the bolster at the approximate centerline of the nonmetallic plates described above. The secondary suspension spring may comprise a variety of materials, such as a Hytrel® material. The spring may also include several separate components and may or may not include sufficient space within a main spring body where these separate components can be installed. In one example, a characteristic of the secondary suspension spring is to have a sufficient reaction for supporting the vertical load of the freight car body both statically and under dynamic conditions as determined from a dynamic numerical analysis. The vertical deflection of the spring under the vertical load of the freight car body may result in a coupler height within the prescribed requirements of the Association of American Railroads, which height may be a maximum of 35 inches, or less than 32½ inches when the freight car body is unloaded, and may further be a maximum of 33½ inches, or less than 31½ inches when the freight car body is loaded. The secondary suspension spring may be made up of a layered arrangement of natural rubber located between steel plates the number of layers of which can vary depending on the desired characteristics of the spring. The secondary suspension spring may include damping characteristics determined from dynamic numerical analysis sufficient to dissipate energy during various railroad track conditions as specified in Association of American Railroads (AAR) specification M-976 and Chapter 11 resulting in the ATS Steering Truck passing the requirements of the AAR. The secondary suspension spring can be mounted on top of the truck side frame and under the truck bolster either vertically or at a slight cant angle not exceeding 100 degrees.
In certain configurations, the freight car truck has dampers that are connected between the side frame of the truck and the truck bolster, one on each side, and located at diagonally opposite corners of the truck from each other. The dampers may have a damping characteristic determined by dynamic numerical analysis, such that the dampers work in conjunction with the secondary suspension springs to dissipate energy during various railroad track conditions as specified in Association of American Railroads (AAR) specification M-976 and Chapter 11 resulting in the ATS Steering Truck passing the requirements of the AAR. The dampers can achieve damping by utilizing a hydraulic device and proper valving to achieve the desired characteristic. The dampers can be mounted between the side frame of the truck and the truck bolster at an angle relative to vertical determined by dynamic numerical analysis to provide the damping required to pass the requirements of the AAR.
In some aspects, the freight car truck includes a truck side frame designed to space the wheel sets apart longitudinally at a length meeting the AAR requirements for standard wheel set spacing. In one embodiment, this spacing may be about 5 feet 10 inches, but that spacing level can vary depending upon the capacity of the truck. The side frames incorporating pedestals at each end can be designed to accept both the special adapter interface to the roller bearing adapter and the roller bearing adapter itself. A transverse member extends from one of the truck side frames to the side frame on the opposite side of the truck to help maintain proper alignment of the two side frames while still allowing for relative rotation of the side frames to facilitate negotiation of the truck in less than optimum track conditions. The end of the transverse member can be inserted into the opposite side frame and include sufficient clearance and a special bushing that facilitate the relative motion on one side frame to the other. The truck side frames can be fabricated from plate steel sufficient in strength to sustain the loads from a fully loaded freight car including such dynamic loads as may occur during operating in service on the North American railroad interchange system and to meet the requirements of the AAR. In other formats, the truck side frames can be made from a casting or combination of a casting and fabrication. The side frames can be configured so that motion between the side frame and truck bolster is inhibited, limited, or controlled by stops both longitudinally and laterally within specific limits as determined by dynamic numerical analysis.
In some forms, the freight car truck has an interface between the side frame pedestals and the roller bearing adapter that allows for motion of the wheel sets, one relative to the other, such that the wheel sets can take on essentially a radial position when negotiating curves. In certain aspects, the truck may include a steering arm assembly, independent of the vertical load carrying members, such as the truck bolster and side frame, connecting to the roller bearing adapters directly through a bolted attachment.
In some examples, the freight car truck includes wheel sets with inboard roller bearings, wherein the length and weight of the wheel sets is much less than the standard outboard roller bearing wheel set. The wheel sets can be configured so that a wheel can be removed from the axle without having to remove the roller bearing. Such a configuration allows for maintenance savings as compared to outboard roller bearing wheel sets, where it is necessary to remove the roller bearing before the wheel can be removed. The inboard mounting location of the roller bearings can reduce, inhibit, limit, minimize, or even eliminate, axle fretting.
In certain embodiments, the freight car truck has brake beams suspended from the ends of the steering arms with a hanger system so that brake shoes of the brake beams are kept in alignment with the wheel treads as the truck negotiates curved and tangent or straight track. In some examples, the brake beams are connected with a tension member, as opposed to a compression member, such that the brake shoes of the brake beams are kept in alignment with the wheel treads when the brakes are applied as the truck negotiates curved and tangent or straight track. The brake heads of the brake beams are allowed to rotate within fixed limits resulting in even, or substantially even, wear of the brake shoes.
The present disclosure describes preferred embodiments and examples of a rail vehicle, the supporting rail trucks, and related components. Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the scope of the invention as set forth in the claims, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept. In addition, it should also be understood that features of one embodiment may be combined with features of other embodiments to provide yet other embodiments as desired. All references cited in the present disclosure and its appendices are hereby incorporated by reference in their entirety.
This application is a continuation of U.S. patent application Ser. No. 16/073,653, filed on Jul. 27, 2018, a national phase application of International Application PCT/US2017/015343, filed on Jan. 27, 2017, and claims the priority benefit of U.S. provisional application No. 62/287,733, filed Jan. 27, 2016, titled “Railway Car Truck System,” the entire contents of said applications which are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62287733 | Jan 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16073653 | Jul 2018 | US |
| Child | 17582993 | US |
