Bolster stop surfaces arrangement for a railcar bogie

Abstract

 A railway bogie assembly has an arrangement for constraining the free travel clearance between the mated bolster and side frame at the side frame window, and more particularly for reducing or eliminating the clearance or separation gap between the bolster lands and the side frame column wall at the outer edges of the bolster lands and the column wall for reduction of bogie warping during service.

Description

[0001] The present invention relates to railcar bogie assemblies and more specifically to the lands between the side frames and bolster of a railcar bogie assembly. Particularly, at each intersection of the side frames with the bolster adjacent to the friction shoe wear plate interface, the facing lands are assembled at a gap separation distance of less than four-tenths inch (10.16mm). Assembly of the bogie with this restriction provides an inhibition to bogie warping with consequent improvement of bogie hunting and curving performance during railcar operation. However, it also induces frequent wearing contact between the sideframe column surface and the bolster stop surface.

[0002] In earlier railcar bogie assemblies, wide laterally extending stop surfaces or lands adjacent to the side frame wear plate and bolster friction shoe pocket have been provided to avoid rotation of the bolster about its longitudinal axis, that is bolster rotation. In the railcar bogie assemblies, each side frame has a longitudinal axis parallel to the truck longitudinal axis, which intersects and is normal to the bolster longitudinal axis at an as-assembled condition. Rotation of the bolster about its central vertical axis causes angular displacement of the intersection of the side frame and bolster longitudinal axes from their perpendicular, as-assembled state, and this action is considered to be bogie warping. In the case of railcar bogie warp, greater clearance between the sideframe and bolster at their intersection aggravates bogie warp causing the wheel flanges to attack the rail at a relatively severe angle during curving, thus inducing excessive lateral forces. Further, if this sideframe-bolster clearance is too great, bogie assembly hunting may be aggravated.

[0003] Railcar bogie hunting is a continuous instability of a railcar wheel-set where the bogie weaves down the track in an oscillatory fashion, usually with the wheel flanges striking against the rail, creating wheel drag and increased lateral forces on the rail. A related condition referred to as lozenging is an unsquare condition of the side frames and bolster, and it occurs where sideframes operationally remain parallel to each other, but one sideframe moves slightly ahead of the other in a cyclic fashion; this condition is also referred to as parallelogramming or warping. Warping results in wheel misalignment with respect to the track; it is more pronounced on curved track and usually provides the opportunity for a large angle-of-attack to occur. The displacement or rotation of the bolster about the bolster vertical axis, which is accompanied by angling of its longitudinal axis relative to the side frame, is indicative of railcar bogie warping. The concept of bogie hunting, that is a high-speed dynamic instability of the railcar wheel sets is manifested by the parallelogramming or lozenging of the bogie. Further, bogie hunting is also a consequence of the lack of warp stiffness.

[0004] Wide stop surfaces on the bolster lands were provided to inhibit rotation of the bolster in the side frame and to avoid the cited bolster rotational problems about its longitudinal axis; to permit as-cast surfaces to function properly; and, to avoid the wearing or eroding of the contacting surface edges between the bolster and the columns of the side frame bolster opening.

[0005] The earlier practice of a narrow-land structure with a wide separation between the bolster land and side-frame, column-face land is illustrated in U.S. Patent No. 2,378,415 to Light. In this patent, inboard and outboard column guide gibs are provided on the bolster for engagement with the inboard and outboard surfaces on the adjacent column. The outboard gibs in this structure have less depth than the widened portion of the bolster opening. A similar gib arrangement is taught in U.S. Patent No. 2,422,201 to Lehrman. The significant separation distances between the side frame column and the bolster are clearly discernible in the plan views of the figures of these patents.

[0006] A technical study of a number of railcar derailments between 1988 and 1992 was conducted by a task force composed of representatives from five railroads, three railcar builders, three bogie manufacturers, a major shipper, a major railcar fleet owner, as well as other component suppliers and technical consultants. The task force was to determine the cause of the derailments and to recommend both long-term and short-term solutions for derailment prevention. The results of the study are reported in Final Report, Testing, Evaluation & Recommendations Curving Performance of 125T DS Cars by Rail Sciences Inc.(RSI), Atlanta, Georgia, February 12, 1993. One of the parameters considered in the bogies was warp restraint, and as a consequence of the research it was determined that one of the five simultaneously occurring factors leading to the derailments being reviewed was 'warping of sideframe-bolster due to low truck warp restraint'. One of the consequent long-term proposals resulting from the test determinations was to advocate the development and application of bogie warp stiffening techniques. A principal finding of the study was that frame stiffening arrangements increase the warp restraint of the bogies and reduce lateral forces in curving. In addition, it was concluded that the studied derailments were the result of high lateral forces rolling the low rail or increasing total gage sufficient to allow a wheelset to drop in. One of the noted causes of these high lateral forces was warping of the sideframe-bolster combination due to low bogie-warp restraint caused by the presence of resilient bearing adapter pads and a lack of friction wedge restraint. There were a plurality of other findings and conclusions from this study, which were noted in this report, however, the present invention only addresses the warping restraint within the railcar bogie.

[0007] U.S. Patent no. 4,274,340 to Neumann et al. specifically teaches a frictional snubbing arrangement having inner and outer gibs, which gibs are bowed to aid in the prevention of bolster roll and to maintain control of the bolster. There is no other known bowed element structure in the friction shoe pocket and bolster end arrangement.

[0008] As a consequence of the more narrow gap between the contact surfaces there is more friction and wear between the surfaces during the operation of the railcar bogie assembly. The wear on the bolster column-stop surface is the result of the contact, and also the consequence of the ongoing effort to reduce bogie hunting and railcar warping. The restraints or constraints on the railcar bogie produce increased contact and wear. Therefore, suppliers of railcar bogies are continuously searching for methods and components to reduce the wear on the bogies and bogie components to increase the bogie or component useful life along with improved operating performance.

[0009] In one aspect the present invention provides a bolster land structure for the bolster of a railcar bogie assembly, which land structure has been hardened to increase the surface hardness of the contact surface. More particularly, the surface is preferably provided with a contacting surface that has Brinell hardness between about 375 BHN and 515BHN with an effective hardness depth of about 0.12 inch (3.05mm), which hardness is significantly greater than the as-cast steel hardness of 137BHN to 208BHN of AAR-specified M-210 Grade B+ steel. Preferably the surface hardness is increased by flame-hardening. The resultant bolster surface produces a significant increase in bolster contact-surface wear reduction when contacting the sideframe column contact surface or the wear plate generally mounted on the column surface. This wear reduction is further amplified in those cases where a hardened wear plate is mounted on the column wear surface and contacts the bolster contact-surface. Although the increased hardness is directly reflected in the improved wear life of the bolster land or contact-surface, an ancillary benefit, or consequent result of the improved wear life is an improvement of friction shoe wear and increase of the useful life of the associated friction shoe.

[0010] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is an oblique view of a representative three-piece railcar bogie assembly;

Figure 2 is an enlarged oblique view in partial section of a portion of the side frame and bolster connection in Figure 1 at the columns of the side frame;

Figure 3 is a plan view of a side frame and bolster connection at a reference and normal position;

Figure 3A is a plan view of a side frame and bolster connection with a column wall and bolster wall contact surface;

Figure 4 is a plan view of the side frame and bolster connection of Figure 3 wherein the bolster and side frame are angularly displaced from the reference position;

Figure 5 is a partial section of a plan view segment of a side frame and bolster intersection of prior art wide land arrangements;

Figure 6 is an elevational view of the side frame column, as noted in Figure 5;

Figure 7 is a side elevational view of a representative interface between a wear plate on a side frame column and the friction shoe;

Figure 8 is a side view of a bolster land segment noting the convex central portion;

Figure 9 is a front elevational view of a three-piece railcar bogie bolster pocket with the flame-hardened sections noted thereon; and,

Figure 10 is a plan view of a three-piece railcar bogie at a reference or normal position and illustrating the various moments and forces acting on such bogie assembly.

[0011] Railcar bogie assembly 10 in Figure 1 is a representative three-piece bogie assembly for a freight railcar (not shown). Assembly 10 has first side frame 12, second side frame 14 and bolster 16 extending between generally central openings 18 and 20, which openings 18 and 20 in Figure 2 are between forward sideframe column 17 and rearward sideframe column 19, of first and second side frames 12 and 14, respectively. In Figure 1, railcar longitudinal axis 34 is parallel to both first and second side frame longitudinal axes 36 and 38. Bolster longitudinal axis 40 is generally perpendicular to railcar axis 34 and, side frame longitudinal axes 36 and 38 at the railcar as-assembled reference position. First axle and wheel set 22, and second axle and wheel set 24 extend between side frames 12 and 14 at their opposite forward ends 26 and rearward ends 28, respectively, which side frames 12 and 14 are generally parallel at a reference, as-assembled condition. First bolster end 30 is nested in first side-frame opening 18 and second bolster end 32 is nested in second side-frame opening 20.

[0012] The connection of bolster 16 in openings 18 and 20 is similarly configured for either of side frames 12 and 14. Therefore, the following description will be provided for the connection of bolster first end 30 at first side frame opening 18, but the description will also be applicable to the connection of bolster second end 32 in second side frame opening 20. Opening 18 and bolster first end 30, which are illustrated in an enlarged and partially sectioned view in Figure 2, have exposed bolster columns 42 and 44 between gibs 50 and 52. Friction shoe pockets are provided within bolster columns 42 and 44 with respective friction shoes 46 and 48 therein. At each end of bolster 16, friction shoe-pockets and friction shoes 46 and 48 as well as bolster columns 42 and 44 are longitudinally arranged on forward side and rearward side of bolster 16, respectively, which bolster columns also provide lands 96 noted in Figure 3A. As bolster columns 42, 44 and friction shoe-pockets and shoes 46, 48 at each bolster end are similar, only one arrangement will be described, but the description will be applicable to various sets of friction shoe-pockets and friction shoes and bolster columns 42,46 and 44,48. Bolster gibs or lugs 50 and 52 in Figures 2 and 5 project from bolster side wall 54 and are arranged outboard and inboard, respectively, on both the forward and rearward bolster columns 42 and 44, which gibs 50, 52 act to maintain the position of the sideframe therebetween on either side of bolster 16 at each side frame. Although gibs 50 and 52 are shown as relatively independent elements, these elements may be cast or formed as enlarged protrusions of bolster 16.

[0013] The general configuration of friction shoe 48 in a friction shoe pocket provided within bolster column 44 is more clearly illustrated in the sectional view of Figure 7 with bolster wall 60 in proximity to friction shoe sloping surface 62. Side frame column wall 66 has wear plate 68 with vertical wall frictional surface 70 to contact vertical surface 72 of friction shoe vertical wall 73.

[0014] Gap distance 86 is particularly shown in Figures 3A and 5. In Figure 3A, gap distance 86 is noted between side frame column wall 66 and bolster column wall 54 and in Figure 5, gap 86 is noted between land 96 on bolster column 54, and surface 92 of side frame land 94. The specific locating point may vary with the design of the bolster column and side frame column arrangement. However, the gap distance 86 is generally about three-eighths inch (9.55mm) up to approximately one inch in present railcar bogie assemblies.

[0015] In a specific prior art embodiment, the railcar bogie arrangement in Figure 5 has separation gap 86 between projections 94 and bolster sidewall 54. However, in the structure of Figure 5, projections 94 have a longitudinal width significantly greater than predecessor arrangements, and this structure has been dubbed the wide-land arrangement. This wide-land structure was intended to reduce rotation of the bolster about bolster longitudinal axis 40 relative to the side frame, and to reduce wear on the side frame and bolster surfaces which come into contact during service operations. In this embodiment, surfaces 92 of lands 94 were to contact surfaces 96 of bolster 16. Lands 94 were elongated projections on the column of side frame 12 with wear surfaces 92 closely adjacent spaced guide surfaces or lands 96 of column 54 of bolster 16.

[0016] The angular displacement between side frame 12 and bolster 16 is illustrated in Figure 4 by the angular displacement or warp angle 98 between side frame longitudinal axis 36 and bolster transverse axis 41. In one measured arrangement, this angular displacement was noted as 1.540. During operation, railcar bogie 10 is displaced from its reference position with longitudinal axes 38 of sideframes 12 normal to longitudinal axis 40 of bolster 16. The angular displacement has been referred to as warping of the railcar bogie. The forces affecting or impacting the warping characteristics are noted in Figure 10 by the various arrows, wherein a turning moment is noted at the center plate region of the bolster, lateral forces are acting at the ends of the bolster and longitudinal forces are inducing steering moments.

[0017] In Figure 3, the interface between the contact surfaces of the lands, conventional or wide-land designs or rotation stops are provided in contact with each other, or at a negligible separation distance 86. It has been found that providing this close proximity of the lands at the interface of bolster 16 and side frame 12 or at the bolster columns, limits or improves warping of bogie assembly 10. In this embodiment of Figure 3, gap or spacing 86 has been closed for direct contact between wear plate 68 and lands 96 on bolster 16. Lands 96 are formed on the surface adjacent to the friction shoe pockets. In this embodiment, wear plate 68 extends across the width of side frame column wall 66. However, it is noted that projections or lands 94 are provided on either side of wear plate 68 in Figure 5, and land or front face 92 of these lands may be coplanar with the surface 70 of wear plate 68.

[0018] Figure 3A shows the bolster column wall or spaced guide surface 96 as a continuum between gibs 50 and 52. Similarly, vertical walls 66 of the side frame column are each noted as a single vertical wall. In this embodiment, the utilization of a friction shoe and friction pocket have been obviated. In a further enhancement of this embodiment, the vertical surfaces 66 and 96 may be hardened surfaces.

[0019] Although wear plate surface 70 in Figures 5 and 7 is noted in contact with surface 96 in Figure 3, tests have noted that control of the angling between bolster 16 and side frames 12 or 14, can be accommodated when gap distance 86 is less than four-tenths (0.40) inch (10.16mm), and preferably closer to fifteen thousandths (0.015) inch (0.38mm). In an experiment on a railcar bogie with the requisite reduction in gap distance 86, the bogie warping or lateral stability of the bogies was maintained to meet AAR Chapter XI stability criteria (0.26G rms at 70mph) for a Super Service Ridemaster® Truck Assembly with double roller side bearings, as was another railcar truck assembly with constant contact side bearings (CCSB). Control of the angling-warping condition in the truck assembly by increasing the warp stiffness improves the lateral stability and reduces the lateral curving forces at the wheel to rail interface, thereby improving the hunting and curving performance of bogie assemblies especially in a particular freight railcar, a bulk-head flat railcar. Limiting the gap separation distance minimizes or limits the permitted warping angle to an angular displacement between about 0.1° (1.7 milliradians) and 2.0° (35 milliradians). All of these attempts to control warping or bogie hunting result in increased wearing contact between the contact surfaces of the sideframe columns and the bolster contact surfaces.

[0020] In Figure 8, bolster land or contact-surface 96 is noted in a side view with upper edge 110, lower edge 112 and inner gib 50. However, contact surface 96 has a bowed or convex contour. A projected planar surface is outlined by dashed line 114, but as indicated surface 96 includes upper tapered surface 116, lower tapered surface 118 and central surface 120. Tapered surfaces 116, 118 extend from upper surface 110 and lower surface 112, respectively, to intersect central surface 120. Tapered surfaces 116 and 118 may be of equal length, but this is not a requisite. Further, in the illustration of Figure 8, tapered surfaces 116, 118 are longer in length than flat segment 120, as an illustrative embodiment. The specific slope of the surfaces 116 and 118 allows for limited movement between the sideframe and bolster 16 at the bolster pockets.

[0021] This bowed element structure provides for equalization of the travel or ride of the sideframe relative to the bolster. Failure to provide at least a nominal degree of freedom for travel between the sideframe and bolster would inhibit the sideframe from following the wheelset or wheelsets in their vertical travel as the railcar progresses down the track. Potentially wheelset 22 or 24 could literally drop out of the pedestal jaw at forward end 26 or rearward end 28 in an extreme condition. The relative degree of movement or freedom between the bolster and sideframe accommodates the rock between the bolster and sideframe. This concern was analyzed in an empirical test, which relieved the load from one of wheels 23 of a bogie assembly to analyze the impact on the remaining wheels within bogie assembly 10.

[0022] The primary contact between bolster land 96 and sideframe column contact surface 92, or a wear plate 68 on column surface 92, is borne at central and flat segment 120. Although noted in a flat configuration, it is recognized that segment 120 may be contoured or bowed, and thus flat 120 is not a limitation. In Figure 8, the bowed central surface 120, which can be flat as shown, has been hardened by a flame hardening process to elevate its temperature above a transformation temperature, and thereafter the surface is quenched. The resultant surface hardness of the hardened region is in the range of Brinell hardness 375BHN and 515BHN. This is significantly higher than the as-cast regions of tapered regions 116, 118, which are generally in the range of 137BHN to 208 BHN for AAR specified steel M-210, Grade B+. Although it is preferred to merely harden the local region 120, it is recognized that the entire length of land 96 could be hardened. Further, it is recognized that region could be hardened by alternative means such as induction hardening or by provision of a hard coating from a process like flame-spraying. The latter condition must accommodate variations in dimensional shifts. In addition, it is acknowledged that other base materials such as AAR Grades B and C may be used in the manufacture of the bolster or sideframe and hardened in a similar manner.

[0023] In Figure 9, it is noted that both bowed sections 120 of each bolster shoe pockets are hardened across the width of contact surface 96. At this elevated hardness, the wear rate of bowed section 120 is reduced from its rubbing and frictional contact with wear plate 68 or column contact surface 66. Wear plates 68 have a Brinell hardness of approximately 400BHN, thus the wear rate between plate 68 and bowed section 120 is now provided at relatively equivalent and higher hardness rather than having a high-hardness wear plate 68 rubbing on a softer surface of as-cast bowed section 120.

[0024] Further, the increased longevity of bowed section 120 helps to reduce the total load and subsequent wear on a friction shoe, such as shoe 46, in the bolster pocket by maintaining its conformation relative to wear plate 68.

[0025] In Figure 7, the bowed or convex shape of the friction shoe and bolster pocket are noticeable. However, the convex region 120 of the vertical bolster contact surface is more clearly illustrated in Figure 8. In this figure, bolster land or contact surface 96 has generally centrally located region 120 convex from base surface 96 noted by the partial dashed vertical line 114. In the illustration, the vertical length of the region 96 is less than one-third of the total length of bolster 1 and 96.

[0026] In Figure 9, the bolster pocket with friction shoe 46 and lands 96 are noted in a front elevational view having both contact lands 96 and friction shoe 46. It is noted that friction shoe face 72 contacts column surface 70 on wear plate 68 as shown in Figure 5. In these figures, the present structure of the bolster of a railcar bogie assembly is specified by the Association of American Railroads, AAR, as a steel alloy with AAR specification M-210, Grade B+ with an as-cast Brinell hardness between 137BHN and 208BHN.

[0027] The flame hardening process may utilize a natural gas, acetylene or other high-temperature gas source. The bolster land regions 120 of each bolster pocket are elevated above a transition temperature of about 1700°F and thereafter quenched to maintain the hardness and underlying microstructure. Although the illustration of the increased hardness zone in Figure 8 is noted with an uniform depth, it is recognized that there is a gradient between the surface hardness and the hardness below the surface, which gradient will be within the cited hardness range.

[0028] In the present case, the effective hardness has been measured to extend to a depth of at least 0.12 inch (3.05mm) while providing a Brinell hardness of at least 300BHN at that depth. This is an increased hardness range to provide a surface hardness better able to resist the frictional wear from contact with column contact surface 66 or wear plate 68, which wear plates 68 are known to have a hardness of about 400BHN. The bolster land region is an adjunct member of the friction shoe damping structure and avoidance of its premature wear by contact with a harder, and thus more aggressive, surface enhances the longevity of the damping structure.

[0029] While only specific embodiments of the invention have been described and shown, it is apparent that various alterations and modifications can be made therein. It is, therefore, the intention in the appended claims to cover all such modifications and alterations as may fall within the scope of the invention.

Claims

1. A railcar bogie assembly, said bogie assembly having a bolster, a first sideframe, a second sideframe and a bogie longitudinal axis,

each said railcar bogie first and second sideframe having a sideframe opening, a forward column and a rearward column,

each said forward column having a forward-column surface and a column stop-surface, and each said rearward column having a rearward-column surface and a column stop-surface,

said bolster having a first end, a second end, a forward bolster side with a bolster stop-surface at each said first and second end, a rearward bolster side with a bolster stop-surface at each said first and second end, and a bolster longitudinal axis,

one of said bolster first and second ends mated with an opening of one of said first and second sideframes and the other of said bolster first and second ends mated with the opening in the other of said first and second sideframes,

said forward bolster side and rearward bolster side at each of said mated first and second bolster ends in proximity, respectively, to a forward-column surface and a rearward-column surface in said respective mated first and second sideframe opening,

said sideframe column stop-surfaces at said forward and rearward column surfaces in proximity to said bolster stop surfaces, which bolster stop-surfaces are operable to contact said respective proximate sideframe column-stop surface to maintain control of the warp angle between said bolster end and said sideframe during curving of the railcar bogie assembly for utilization of said railcar-bogie bolster and, first and second sideframe to reduce hunting of said railcar bogie assembly,

said bolster column stop-surface being hardened to increase said bolster column stop-surface hardness above an as-cast hardness to reduce the rate of wear of said bolster column stop-surface.

2. A railcar bogie assembly as claimed in Claim 1 wherein said bolster stop-surface is hardened to a hardness between about 375BHN and 515BHN to a depth of about twelve hundredths inch (0.021mm) below said stop surface.

3. A railcar bogie assembly as claimed in
Claim 1 wherein said bolster has a stop-surface for mating contact with a sideframe column stop-surface during operation, said bolster stop-surface being as-cast to a surface hardness between about 137BHN to 208BHN,
   said bolster column stop-surface operable to contact said column stop-surface, said bolster stop-surface hardened to elevate said surface hardness to a hardness between 375BHN and 515BHN to reduce the rate of wear on said bolster stop-surface from contact with said column stop-surface and increase operational life of said bolster stop-surface.

4. A railcar bogie assembly as claimed in
Claim 1 wherein said bolster has a stop-surface for mating contact with a sideframe column stop-surface, said bolster stop-surface hardened to a hardness between about 375BHN and 515BHN to reduce the wear rate between said sideframe column and bolster stop-surfaces and to maintain closer clearances between said stop-surfaces to increase warp stiffness and decrease high-speed instability in said bogie assembly over the life-cycle of said bogie assembly.

5. A railcar bogie assembly as claimed in any preceding claim having a bolster, a first sideframe, a second sideframe and a bogie longitudinal axis, further
comprising a plurality of wear plates, a wear plate secured on each said column stop-surface, said bolster stop-surface operable to contact at least one of said wear plate and sideframe column stop surface during operation of said bogie assembly,

each said bolster having a top side and a bottom side,

each said bolster stop-surface having a convex region generally centrally located on said bolster stop surface between said bolster top side and said bottom side,

said convex region hardened to approximately between 375BHN to 515BHN to increase the wear life of said convex region,

said convex region operable to contact at least one of said sideframe column stop surface and a wear plate on said column stop surface.

6. A railcar bogie assembly as claimed in any of claims 1 to 4 having a bolster,
a first sideframe, a second sideframe and a bogie longitudinal axis, further comprising a plurality of wear plates, a wear plate secured to each said column stop-surface, said bolster stop-surface operable to contact at least one of said wear plate and sideframe column stop surface during operation of said bogie assembly,

each said bolster column stop surface having a friction-shoe pocket, an inner stop-surface and an outer stop-surface,

each said bolster inner and outer stop-surface having a convex region generally centrally located on said bolster stop surface, said convex region operable to contact at least one of said sideframe column stop surface and a wear plate on said column stop surface to inhibit bogie hunting and permitting constrained generally vertical movement of said bolster stop-surface relative to said sideframe stop-surface.

7. A railcar bogie assembly as claimed in claim 6 having a bolster, a first sideframe, a second sideframe and a bogie longitudinal axis, said bolster stop-surface operable to contact at least one of said wear plate and sideframe column stop surface during operation of said bogie assembly,

said bolster having a top side and a bottom side,

each said convex region being generally flat and about centrally located between said bolster top side and bottom side,

each said stop surface having an upper tapered region extending from said top side to said convex region, and a lower tapered region extending from said bottom side to said convex region.

8. A railcar bogie assembly as claimed in claim 7 having a bolster, a first sideframe, a second sideframe and a truck longitudinal axis,

said generally flat region having a first length,

said upper tapered region having a second length, and said lower tapered region having a third length, said second length and said third length being about equal.

9. A railcar bogie assembly as claimed in claim 7 having a bolster, a first sideframe, a second sideframe and a bogie longitudinal axis,

said generally flat region having a first length,

said upper tapered region having a second length, and said lower tapered region having a third length,

said bolster defining a vertical length between said top side and said bottom side,

said first length being less than one-third said vertical length.

10. A railcar bogie assembly as claimed in claim 9 having a bolster, a first sideframe, a second sideframe and a bogie longitudinal axis,

said generally flat region having a first length,

said upper tapered region having a second length, and said lower tapered region having a third length,

said first length being less than any of said second length and said third length.

11. A railcar bogie assembly as claimed in any preceding claim wherein said bolster column stop-surface is hardened by flame-hardening.

12. A bolster column stop-surface as claimed in any preceding claim.

Drawing