GB2345682A - Tilting wagon for transporting containers - Google Patents

Abstract

The wagon (10) for use on railway track within a specified gauge, comprises a wagon body (12), a pair of bogies (16) supporting the wagon body, and a plurality of side bearings on the bogies configured to impart a particular outward tilt angle to the wagon body and containers (36) when the wagon is on a curved track, such that larger containers can be transported on the wagon within a predetermined loading gauge.

Description

Method and Apparatus for Maintaining Large Containers Within Gauge on Curved Track Background of the Invention The invention relates to freight wagons, and more particularly to a freight wagon for carrying containers.

Transportation of containers on UK railways is limited by the upper part of the loading gauge. Group Standard GM/RT2149 "Kinematic Gauging Requirements for Railway Vehicles"defines a basic gauge--designated as W6A--for freight wagons in Appendix E. This gauge does not allow the carriage of containers, but an enhancement, or"exception gauge"is defined in Appendix G. This allows for the carriage of 8'-6" high containers of 8'-0" (2.438m) width.

It is now desired to carry containers of 9'-6"and 2.5m wide in the same exception gauge on a lower deck wagon.

As the wagon negotiates a curve its inner side overhangs the curve and tends to move out of gauge. This is accounted for in the gauge width if 8'0" (2.438m) wide containers are carried but not if 2.5m containers are carried. The 2.5m container overhangs the gauge in its upper corner by about 25mm to 35mm depending on the spacing of the bogie centers.

Increased spacing of the bogie centers causes greater overhang. Similar problems may exist for container cars or other railway cars in the U. S., and for other similar equipment elsewhere.

Summary of Invention In accordance with the invention, the top corner of the container on the inside of the curve is maintained in gauge by tilting the wagon toward the outside of the curve. The amount t of tilting must be carefully controlled, in that the degree of tilting must be sufficient to maintain the inside top corner of the container in gauge, but not so great as to cause the outside top corner to infringe the gauge. Also, the tilting must not cause the container to exceed gauge height restrictions. Furthermore, the tilting must not shift the center of gravity of the loaded wagon to such an extent as to destabilize it. The desired degree and control of tilting can be accomplished by appropriate configuration of side bearings, e. g., by use of tapered side bearings on tapered wear plates.

As the wagon enters a curve, the bogies rotate in yaw and the side bearings slide along wear plates. In contrast to conventional side bearings and wear plates, which are horizontal and keep the wagon vertical, the wear plates in accordance with the invention are tapered. The effect is to tilt or roll the wagon outward as it enters the curve.

When a wagon negotiates a curve, the bogies have yawed through some angle and the side bearings have slid along their wear plates by some distance for the side bearings on the inside of the curve and the same distance in the opposite direction for those on the outside. In order for the wagon to lean out of the curve, the force on the inner side bearings must increase and that on the outer side bearings must decrease. This may be accomplished by tapered wear plates in conjunction with spherical center pivots as present on the Y25/Y33 type of bogie. The center pivot does not restrict the roll of the body and allows the side bearings to control body lean. The AAR style center plate is flat and does not permit the side bearings to roll the wagon.

In a preferred embodiment, the top corner of the container is moved laterally by about 31mm and is about 2700mm above the bogie pivot. The angle of roll is thus about 0. 66 .

To achieve this with a side bearing placed 850mm from wagon centerline (larger than standard) requires a wedge rise of 6.7mm. This is required to be achieved in a 200m radius curve (GM/RT2149, F. 3. 1). At this curve radius and with a 15 388m bogie center the bogie yaw angle is 2.2o. The side bearing will have slid 32.7mm along the wear plate. The wear plate slope is 0.20.

On a minimum radius curve of 50m the bogie yaw angle is 8.85 . If the wear plate slope extended for the full length of travel of the side bearings, the wedge rise would be 27mm and sliding movement would be 131.6mm. This would produce a larger roll angle than is required, and might have undesirable consequences. Accordingly, it may be preferable to flatten out the taper beyond 32.7mm.

As the wagon enters a curve the lead bogie begins to yaw.

This causes one side bearing to ride up the wedge and the other to ride down. The side bearing riding up the wedge has to overcome a force component produced by the body weight.

The opposite side bearing is assisted by a similar force component.

As the truck yaws, it must roll the wagon body. This will be resisted by the wagon's roll inertia and will result in an increased yaw moment on the bogie. This effect will be worse for heavily loaded wagons entering curves at high speed However, the natural tendency of the body to roll outward on the curve will assist the process.

It may be desirable to reduce side bearing friction in one or more regions of contact between the side bearings and wear plates. Such reduction of friction may be effected by relief of one or more regions of the wear plates. In the preferred embodiment, the upper level portion of each wear plate is relieved by about 1/8 in. This results in the side bearing on the outside of the wagon remaining on a sloped wear plate surface slightly longer than the inner side bearing, which should facilitate bogie yaw on tracks of less than 200m radius as the wagon enters the curve, and may also result in decreased resistance to straightening of the bogie as the wagon exits a curved track portion.

The total amount of roll is within the amount that might occur with normal wagon dynamics and a lateral Cg shift of 35mm should be inconsequential to vehicle stability.

Brief Description of Figures Fig. 1 is a plan view of a wagon for carrying a tall container in accordance with an embodiment of the invention.

Fig. 2 is a side elevational view of the wagon of Fig. 1.

Fig. 3 is a schematic diagram showing how a wagon disposed between two bogie centers on a curved segment of railroad track is disposed inwardly toward the center of curvature.

Fig. 4 is a schematic diagram showing detail with respect to one of the particular exception gauges designated in Fig 5.

Fig. 5 is a schematic diagram showing the general configuration of a loading gauge for containers with particular exception gauges designated by hatching.

Fig. 6 is a schematic diagram of the arrangement and orientation of tapered side bearings in accordance with an embod-ment of the invention.

Fig. 7 is a schematic diagram of a tapered interface between a side bearing and a wear plate in accordance with an embodiment of the invention.

Fig. 8 is a cross-sectional view of a first type of side bearing in accordance with the invention.

Fig. 9 is a cross-sectional view of a second type of side bearing in accordance with the invention.

Fig. 10 is a cross-sectional view of a third type of side bearing in accordance with the invention.

Fig. 11 is a cross-sectional view of a fourth type of side bearing slidable on a wear plate in accordance with the invention.

Fig. 12 is a plan view of the wear plate shown in Fig.

11.

Detailed Description of Preferred Embodiments As it is desired to carry high containers within the aforedescribed loading gauge (with exceptions) or within any particular predefined gauge or cross-sectional profile, preferred embodiments of the invention include a wagon having a deck at a lower elevation off the ground than is typical for container-carrying wagons. The lower deck elevation permits higher containers supported on the deck to fit within a predefined gauge. Figs. 1 and 2 show a wagon 10 having such a lowered deck. It can be seen therein that the wagon, which is supported at its raised ends 14 by bogies 16, descends between the bogies to a height only slightly above the railroad track 18.

Bogies 16 in the preferred embodiments support the raised ends 14 of the wagon body 12, and each bogie 16 includes four wheels 20 associated with a pair of axles 22, a pair of side frames 24, and a bolster 26. The bogie center plate 28 supports the wagon body 12. A pair of side bearings 30 are mounted on top of the bolster on opposite sides of the center plate and between the side frames 24.

Transportation of containers in the United Kingdom and elsewhere is typically associated with configurational limitations to permit for the safe placement of railroadassociated hardware alongside and above the railroad track.

Fig. 5 schematically shows a general configuration of a loading gauge 32 for containers (as shown by Group Standard GM/RT2149 w6A), and specific, hatched enhancements 34 (exceptions to the basic gauge).

This gauge and exception have generally been sufficient to allow carriage of 102 inch high containers having a width of 96 inches. It is now desired to carry 114 inch high containers having a width of 2. 5 meters (about 98.4 inches) through the same loading gauge (with the same exceptions).

However, as the wagon negotiates curved railroad track, it and the container thereon move relatively toward the center of curvature, especially at the portion of the wagon not proximate to either wheel truck (see Fig. 3) At the minimum radius of curvature typically encountered, the 2.5 meter wide container overhangs the gauge in its upper inner corner by about 25 to 35 millimeters, depending on the spacing between the bogies on opposite ends of the wagon. Increased spacing between bogie centers causes a greater amount of overhang As further seen in Figs. 4 and 5, a 2.5 meter wide container, which would otherwise infringe the loading gauge in the manner described, would avoid such infringement if it could be controllably rotated away from the center of curvature about a longitudinal axis through the center pivot or center plate 40 as shown in Fig. 5. Fig. 4 shows a closeup of how the exception gauge 34 is infringed by a vertical container 36 while not infringed by a controllably rolled container 38 (opposite direction of curvature from Fig. 5).

The amount of rolling or tilting of the container must be carefully controlled. The degree of rotation must be sufficient to maintain the inside upper corner of the wagon within gauge at the midpoint between the bogie centers, but not so great as to cause the outside upper corner of the wagon at an end of the wagon to infringe gauge on the opposite side Additionally, at the midpoint between the bogie centers, if the container is overly rotated, the upper inner corner could infringe an upper portion of the loading gauge or an upper portion of the exception gauge.

Yet another concern for over rotation relates to destabilization of the container. As the longitudinal axis of rotation is not at the center of mass for the container (because the center plate is under and supports the container), the center of mass will shift outwardly as a result of the controlled rotation. Although it must be ensured that the container is not rotated so much as to destabilize it, the loading gauge will typically present much stricter limitation on over rotation than will destabilization.

The controlled rolling of the container to avoid infringing the loading gauge is preferably accomplished by the use of appropriately configured side bearings. The preferred embodiments employ a tapered interface.

Fig. 6 schematically shows how side bearings might interface with tapered wear plates to roll a container. If the schematic in Fig. 6 were moving toward the right side of the page, for example, and encountering a right-hand curvature in the tracks, the front wheel truck would yaw clockwise and the rear wheel truck would yaw counterclockwise as indicated.

This would cause the side bearings on the right side of the truck to converge slightly, thereby sliding to the descended portions of the tapered wear plates and causing upward force to be exerted from the right-hand side bearings 44. On the left side, the side bearings 46 would diverge slightly, causing them to slide to the ascended portions of the tapered wear plate and permitting the wagon body to roll to the left.

The magnitude of slope encountered at the interface of the side bearing and wear plate will determine how much roll a particular track curvature causes.

To permit the wagon body to roll or lean, one may use a spherical center pivot, as present on the Y25/Y23 type of bogie-The spherical center pivot does not restrict roll of the body and allows the side bearings to control body lean.

Fig. 7 schematically shows geometry for an interface between a side bearing and a wear plate that would limit the amount of container roll or rotation. In particular, after the side bearing slides a predetermined distance with respect to the wear plate, the incline of the interface levels so that continued sliding causes increasingly less rotation or does not cause any further rotation.

In one embodiment, each of the four interfaces between side bearings and wear plates would reach its level portion or decreased taper at approximately the same degree of rotation.

However, it may alternatively be desirable to reduce side bearing friction in one or more regions of contact between the side bearings and wear plates. Such reduction of friction may be effected by relief of one or more regions of the wear plates. To this end, the upper level portion of each wear plate may be relieved by about 1/8 inch. This results in the side bearing on the outside of the wagon remaining on a sloped wear plate surface slightly longer than the inner side bearing, which should facilitate bogie yaw on tracks of less than 200m radius as the wagon enters the curve, and may also result in decreased resistance to straightening of the bogie as the wagon exits a curved track portion.

Figs. 8-11 depict different configurations for a side bearing and a wedge or inclined wear plate to achieve an inclined interface therebetween. Fig. 8 depicts a first configuration of side bearing 50 having an elastomeric spring 52 disposed inside a housing 54 mounted vertically on the bolster 26. A contact element 56, such as a metal block, contacts the wedge 43 along an inclined region thereof.

Fig. 9 shows a second configuration of side bearing 58 akin to that shown in Fig. 8 except that the housing 54 is mounted on an incline atop the bolster 26. The incline may be provided by a wedge-shaped intermediate member 60 or other means, and the incline helps align the contact force between the contact element 56 and the wear plate 43 with the orientation of the housing 54 (as compared with the embodiment t shown in Fig. 8).

Fig. 10 shows a third configuration of side bearing 62 having a housing 64 compressibly telescoping a similarly shaped base 66 with a pair of elastomeric springs 68 therebetween. An annular bearing 70 encircles a shaft 72 to act as a contact element with the wedge 43. The contact element is additionally supported by an elastomeric friction block 74 to provide yaw friction.

Fig. 11 shows a fourth configuration of side bearing 76 having a base 78 mountable to the bolster 26. A cradle 80 fits into the base 78 and supports a resilient block 82 therein to serve as the contact element with the wear plate 42. A roller 84 is additionally provided to engage the wear plate after considerable deflection or erosion of the contact element. As seen in Figs. 11 and 12, the wear plate 42 is mountable to the wagon body 10 via fastening holes 86.

The minimum degree of container rotation necessary to avoid gauge infringement by a container at a point of concern on the container depends on a number of geometric parameters relating to the gauge, the container, and the track itself.

The radius (R) of curvature of the track at the relevant point affects how far inwardly from center the container is offsetthe tighter the curve (smaller radius of curvature), the greater the offset. Thus, on tight curves, there may be a gauge infringement concern while on subtle curves there may not be. The gauge width (Wg), which includes any exception gauge present, is measured at the height of a point of concern -in this case at the level of the top of the container. The distance (A) between the two bogies on opposing wheel trucks supporting the container also affects the geometry. The greater the distance, the more offset the container will be relative to center on a curved portion of track. The point of concern, assuming a container having a homogeneous cross sectional shape over its length, is generally going to be half-way between the bogies. In this case the distance between the cross section containing the point of concern and the nearest bogie is A/2 and the gauge width is Wdg ed. It is possible, however, for a point of concern to be closer to one bogie than the other, in which case the relevant distance is the distance (N) between the cross section containing the point of concern and the closer bogie. The curve overthrow threshold (K) is the minimum curve overthrow for which gauge width reductions are required for the point of concern. Curve overthrow is the extent to which a transverse cross section of the container is displaced inwardly from the track centerline on a perfectly aligned curve. Assuming that the point of concern is somewhere at the top of the container, because loading gauges typically get narrower toward the top, the height (H or Hn) of the container above its rotation point, the center plate, affects how much rotation is necessary to avoid gauge infringement. Obviously, the width (W or wdcn) of the container at the point of concern is the most critical parameter with respect to gauge infringement on one side of the loading gauge profile. The diagonal distance (Diagcn) between the center of rotation, the center plate, and the typical point of concern, the upper inner corner of the container, is then computable as the diagonal spanning the perpendicular height (H) and width (W) of the container-Thus Diagcn =/" (H + W2), The inventive apparatus and method involve tilting a container to avoid infringing a gauge, and in this respect, the invention is not intended to be limited to particular characteristics or dimensions of gauges and/or apparatus disclosed herein. Rather, it is foreseen that the invention could be employed with significantly different dimensions applying to the gauge (basic or exception) or apparatus.

That being said, in a preferred embodiment of the invention, the top corner of the container is moved laterally by about 31mm and is about 2700mm above the bogie pivot. The angle of roll is thus about 0. 66". To achieve this with a side bearing placed 850mm from the wagon centerline (larger than standard) requires a wedge rise of 6.7mm. This is required to be achieved in a 200m radius curve (GM/RT2149, F. 3.1). At this curve radius and with a 15. 388m bogie center, the bogie yaw angle is 2.2 . The side bearing will have slid 32.7mm along the wear plate. The wear plate slope is thus 0.20.

On a minimum radius curve of 50m the bogie yaw angle is 8.85 . If the wear plate slope extended for the full length of travel of side bearings, the wedge rise would be 27mm and sliding movement would be 131.6mm. This would produce a larger roll angle than is required, and might have undesirable consequences. Accordingly, it may be preferable to flatten out the taper beyond 32. 7mm. The total amount of roll is within the amount that might occur with normal wagon dynamics and a lateral Cg shift of 35mm should be inconsequential to vehicle stability As appreciable from the foregoing description, the inventive wagon provides a significant advantage over conventional container-carrying wagons with respect to fitting taller containers within a prescribed loading gauge. The lower deck and container tilting apparatus permit higher and wider containers to be carried, and thus more freight to be transported. The invention is not limited to the embodiment (s) described herein or to any particular embodiment. The invention is defined by the following claims.

Claims (5)

Claims

1. A wagon for transporting containers on railway track within a specified gauge, comprising a wagon body, a pair of bogies supporting the wagon body, and a plurality of side bearings, characterized in that the side bearings are configured to impart an outward tilt angle as defined below to the wagon body when the wagon is on a curved track: tilt angle 2 Angle-9 where

h'd g r d Angle = acos I 8 = 2t8l1 j Hp~ s 2 l I svd,, f , = the length of the diagonal between the wagon's center plate pivot and the upper corner of the container; Wdg-red gauge width at centerline; Hc = container height above center plate; and WdCn = width width container.

2. A method of maintaining the inward upper corner of a container on a wagon within gauge along the inside of curved track portions, said wagon having a normal, level position relative to the track when traveling on a straight, level track, the method comprising: rolling the wagon body outward from said level position to an outwardly rolled position with a controlled outward roll as the wagon begina travel along the curved track portion, rolling the wagon body outward from said level position to an outwardly rolled position with a controlled outward roll as the wagon begins travel along the curved track portion, thereby displacing the top of the container outward by about 25mm to 35mm while maintaining container height within gauge; maintaining the wagon body in said outwardly rolled position while said wagon is on said curved track portion ; and rolling the wagon back from said outwardly rolled position to said level position when said wagon returns to a straight track portion.

3. A wagon for transporting containers thereon along a railway track such that said containers are maintained within a prespecified cross-sectional profile at each point along said track, said wagon comprising a wagon body, a pair of bogies supporting said body and a plurality of side bearings, said wagon being characterized in that said side bearings cooperate to impart angular offset to at least one of said containers about an axis generally parallel to said track when said wagon encounters non-liner portions of said track, said angular offset being of sufficient magnitude to maintain a most inward point of said container within said profile and being at least of the magnitude dictated by the inequality : Offset > acos [(RW9+2RK+N2-AN)/(R (4H2sW2 > h)]-atan [2H/W] wherein R is the radius of curvature of said non-linear portion of said track, Wq is the gauge/profile width at a cross section including said most inward point, K is the curve overthrow threshold associated with said most inward point, N is the distance from said cross section including said most inward point to the more proximate of said pair of bogies, A is the distance between said pair of bogies, H is the height of said container above a center plate associated therewith, and W is the width of said container.

4. A wagon for transporting containers on a railway track, substantially as hereinbefore described with reference to Figs. 1 to 8, Figs. 1 to 7 and 9, Figs. 1 to 7 and 10 and Figs. 1 to 7,11 and 12 of the accompanying drawings.

5. A method of maintaining the inward upper corner of a container on a wagon within gauge along the inside of curved track portions, substantially as hereinbefore described with reference to Figs. 1 to 8, Figs. 1 to 7 and 9, Figs. 1 to 7 and 10 and Figs. 1 to 7,11 and 12 of the accompanying drawings.