EP0434642A2

EP0434642A2 - A bogie, in particular for high speed rolling stock

Info

Publication number: EP0434642A2
Application number: EP90830590A
Authority: EP
Inventors: Luigi Niccolai; Antonello Gallone; Rodolfo Forzoni
Original assignee: Breda Costruzioni Ferroviarie SPA
Current assignee: Breda Costruzioni Ferroviarie SPA
Priority date: 1989-12-22
Filing date: 1990-12-17
Publication date: 1991-06-26
Also published as: EP0434642A3; IT1236097B; IT8909588A0

Abstract

A bogie for rolling stock, in particular for high speed vehicles, but suitable for use on railway lines not designed for high speed. The bogie comprises a swing bolster (21) carrying the vehicle body, a guide frame (1) carrying a pair of wheel sets (6), means for connecting the guide frame (1), the swing bolster (21) and the wheel sets (6), as well as a braking equipment (10). Each wheel set (6) comprises a pair of wheels (8) keyed to an axle (7) carried by support means for rotation, in particular axle boxes (11) with integral brackets (13). The swing bolster (21), which supports the weight of the vehicle body, rests directly on the wheel sets (6) through elastic supports and the guide frame (1) is not rigid, but articulated, the longitudinal members (2) of the frame (1) being interconnected by articulated cross members (3), the respective joints (4) of which lie equidistant from the centre and in diagonal alignment. The bogie is suitable to be used in operation both on railway lines designed for high and on lines not designed to this purpose. In particular, the performances of the bogie with guide frame unloaded of the vehicle body weight and articulated are considerably better with respect to the dynamic stability, curve inscribability and safety from derailment when passing on skew length track. The constructive solutions adopted make easier the car replacing operation.

Description

The present invention relates to a rail bogie, in particular for rolling stock utilized in high speed travel.
More specifically, the invention relates to a load bearing bogie for passenger carriages designed for operation at speeds up to 300 km/h.
In the art field of vehicles designed to run on a permanent way, the bogie, be it locomotive or load bearing, provides the means whereby traction and braking forces generated by the contact between wheels and rails are transmitted to the vehicle body, and whereby the body is allowed to pivot about a vertical axis passing through its centre of symmetry; the bogie also carries the dead weight of the body and interacts with it in the exchange of such other forces as are generated in transit (flange impact, centrifugal force, etc.).
In this context, a standard bogie for rolling stock comprises a pair of wheel sets, each comprising an axle with two keyed wheels, a pair of disks forming part of the carriage braking system, and an axle box and bearing assembly at each end for supporting the vertical load. The wheel sets are piloted elastically by a frame, that in turn supports a swing bolster to which the vehicle body is connected in a pivotable manner about a vertical axis of symmetry. The standard bogie thus embodied incorporates a dual-suspension system, comprising a first stage between axle box and bogie frame, and a second stage between frame and swing bolster.
The prior art also embraces rail bogies of a type incorporating one suspension stage only; such an arrangement is disclosed in Italian patent 1182317, for example, which shows a bogie wherein the weight of the vehicle body is supported directly on the wheels by way of elastic supports.
In addition to the basic design problems which accompany the increasing spread of high and ultra high speed rail transport, namely safety and comfort, a novel requirement to be met in this field concerns the suitability of use a rolling stock both on tracks dedicated to high speed travel and on tracks not thus dedicated.
Likewise, it is clearly desirable that the various requirements in question be met comprehensively and optimized within the framework of a standard bogie, utilizing readily available components of proven reliability and readily adaptable to a wide range of applications (railway or other). Hitherto, for example, the main preoccupation in designing and building bogies for high and ultra high speed rail travel has been with the need to maximize stability in motion. A bogie constructed on this principle, however, is unsuitable for use on non-dedicated track (medium and low speed travel) generally in poor maintenance conditions and characterized by a somewhat tight radius of curvature (not exceeding 300 m approx) by reason of the limited inscribability to a curve of this bogie.
An object of the present invention is to provide a bogie for high speed rolling stock that affords a comprehensive and optimized solution to the various requirements in question, within the framework of a standard bogie design as specified above.
A further object of the invention is to provide a high speed bogie that can be adapted easily to the various requirements of national and international railway systems and modularized to suit different applications (public railway, underground and tram networks, etc.).
Another object of the invention is to provide a bogie of the above mentioned type wherein the operations of lifting and rerailing are considerably simple, without the need of disconnecting the vehicle body and the bogie.
The stated objects are fully realized in a rail bogie as characterized in the appended claims.
A fundamental and novel feature of the present invention consists in the fact that the bogie frame is elastically connected to the axle boxes of the wheel sets by way of conventional Silentblock type mountings, whilst the swing bolster, bearing the weight of the vehicle body, rests directly on the axle boxes by way of elastic supports. Thus, since the frame is not subject to the vertical load due to the weight of the vehicle body, the guidance of the wheel sets can be optimized by careful selection of the transverse and longitudinal stiffnesses (Ky, Kx respectively) of the connection between frame and wheel sets, which in turn will result in optimized performance characteristics of the bogie from the aspects of dynamic stability and curve inscribability.
Another special feature of the bogie according to the invention is that the bogie frame is not rigid, but articulated, with the cross members connected by ball joints disposed symmetrically and diagonally aligned in relation to the centre of the structure. An optimum solution is thus provided in safeguarding against derailment when negotiating skew track, as the articulation ensures that the wheels of neither set will lose contact with the rails, whilst the frame maintains its stiffness in all remaining working planes.
Further characteristics and advantages of the bogie according to the invention will be apparent from the following description of a not limiting, exemplifying embodiment thereof made with reference to the accompanying drawings wherein:

fig. 1 is a side elevation of the bogie according to the invention, viewed partly in section;
fig. 2 is the plan of a bogie as in fig. 1, viewed from above with parts shown in their entirety and/or cut away in the interests of simplicity;
fig. 3 is an enlarged side elevation of the single stage suspension arrangement of a bogie according to the invention, seen partly in section;
fig. 4 shows a part of the bogie viewed in section through IV-IV, fig. 1;
fig. 5 shows a part of the bogie viewed in section through V-V fig. 1.

With reference to the drawings, it has been indicated at 1 a bogie frame of substantially "H" shape, comprising two parallel longitudinal box members 2 each of which exhibits an enlarged middle section 2a and two end sections 2b extending at a level lower than that of the middle section 2a. The two longitudinal members 2 are interconnected at each end of their respective middle sections 2a by two hollow cross members 3. Each such cross member 3 comprises two sections 3a and 3b of dissimilar length rigidly associated with the relative longitudinal member 2 and connected one with the other by way of a ball joint 4; the frame 1 thus is articulated, and the vehicle remains stable when negotiating skew lengths of track. The ball joints 4 incorporated into the two cross members 3 will be standard production items, and are positioned symmetrically in relation to the centre of the bogie, in diagonal alignment, such that the frame 1 can follow the movement of the wheel sets when encountering any irregularity in the permanent way, while retaining the necessary rigidity in all other planes of action.
Two conventional wheel sets 6 are provided each comprising an axle 7, disposed perpendicular to the two longitudinal members 2 of the bogie frame 1, a pair of wheels 8 keyed to the axle 7, a pair of axle boxes 11 with integral brackets, accommodating bearings 12 to support the two ends of the axle 7, and a pair of disks 9 keyed to the axle between the two wheels 8. Each disk 9 constitutes the moving part of a respective brake assembly 10 of the conventional type and therefore not described in detail, of which the stationary caliper part is mounted to the corresponding end of one of a pair of parallel longitudinal beams 4, each connected to the cross members 3 substantially in alignment with the ball joints 4 and disposed symmetrically in relation to the centre of the bogie. Each beam 5 serve to withstand the braking forces generated axially in opposing directions between the caliper 10 and the relative disk 9 at each end.
With reference in particular to fig. 3, each of the axle boxes 11 incorporates a pair of brackets 13 disposed symmetrically in relation to the axle 7 and accommodating two flexible annular cushions 14 that occupy horizontal positions within a common plane below the wheel axis and are thus likewise symmetrically disposed on either side of the axle. Each cushion 14 comprises an annular layer of rubber 27 sandwiched between two annular layers of aluminium 26. The centre of each bracket 13 affords a tubular seating 15 capable of accommodating a vertical pin 16 in conjunction with a flexible coupling 17 of Silentblock type embodiment, by which the pin is held in position. The pin 16 engages in a further seating 18 formed in the end portion 2b of the longitudinal frame member 2 and is fastened at its two ends, in the Silentblock and in the seating 18 respectively with nuts 19.
This lower seating 18 passes completely through the longitudinal frame member 2 and is sealed at bottom by a plug 20; thus, the frame is easily dismantled for the purpose of servicing the axle 7.
It has been further generally indicated at 21 a swing bolster for supporting the vehicle body, which is of essentially "H" shaped embodiment and comprises two parallel longitudinal box member 22 interconnected by two hollow cross members 23, of which the central parts carry a welded socket 24 to accommodate the king bolt (not shown) of the body. The two longitudinal members 22 of swing bolster 21 are disposed parallel with and directly above the corresponding members 2 of the bogie frame 1.
The swing bolster 21 is supported elastically by the four axle boxes 11, and, more exactly, each end of the two longitudinal members 22 rests on a pair of coil springs 25 positioned on and extending upwardly from the two cushions 14, coaxial with the seatings 15. Each spring 25 thus encompasses the seating 15 of the pin 16, and registers with the underside of the respective longitudinal member 22 in conjunction with a further tubular seating 15a and a further cushion 14.
The connection between the vehicle body and the bogie is ensured by way of shoes 43 on either flank and on the king bolt and socket 24 at centre, the various mating surfaces being embodied in self-lubrificating materials of conventional type offering proven reliability in terms both of function and duration. The torque generated through the shoes 43 in response to the rotational movement of the body provides a turning moment of which the value balances the performance of the vehicle in respect of curve inscribability (flange impact) and dynamic stability, counteracting the tendency to hunt and increasing critical velocity. 28 denotes a slot associated rigidly with each axle box 11, which serves to limit excessive distancing movement between the bogie frame 1 and the swing bolster 21, for example when negotiating a bend, by checking the travel of a stop 29 projecting from the underside of the corresponding longitudinal member 22 of the bolster. Similarly, two abutment surfaces 28a and 29a positioned to the rear of the slot 28 and below the stop 29, respectively, also serve to check the relative movement of the frame and the bolster, and in this instance to keep any contracting movement within the elastic reaction limits of the coil springs 25. Also associated with each axle box 11, in a position alongside one of the two coil springs 25, there is a vertically disposed hydraulic damper strut 30 anchored uppermost to a pair of lugs 31 and sidewise extending from the longitudinal member 22 of the bolster 21, while at bottom is supported by corresponding lugs 32 projecting from the axle box 11.
The bogie further comprises two vertical arms 33, welded on both side of the frame 1 in correspondance to each projecting end of one of the cross members 3, and two respective connecting rods 34 elastically articulated at one end to vertical arms 33 and at the other to pins 35 located externally of the longitudinal members 22 of the swing bolster 21 and firmly connected to one of the relative cross member 23 of swing bolster 21. When the brakes are applied, an anti-pitch torque is generated by the vertical arm 33 and the rod 34. The lenght of the vertical arm 33 is calculated such that this torque will oppose the pitching torque to which the frame 1 is subjected by application of the brakes, and which tends to load the front suspension to a greater extent that the rear, considered in the direction of forward motion.
To the outer side of the longitudinal members 22 of the swing bolster 21, there extend centrally a pair of arms 36, parallel to said members, of which the free ends carry two respective vertical links 37 hingedly anchored by their bottom ends to the longitudinal members 2 of the bogie frame 1. These further arms 36, attached to welded pins 38 issuing from the longitudinal members 22 of the bolster, are interconnected by a torsion bar 39 accommodated internally of one of the bolster cross members 23 and performing an anti-roll function; the relative connections are effected by keying the arms 36 to the ends of the torsion bar 39 by means of conventional expanding fasteners (not illustrated).
40 denotes a pair of transverserly disposed hydraulic damper struts, each anchored at one end to the king bolt socket 24, and at the remaining end to a mounting 41 welded to the inside face of a corresponding longitudinal member 2 of the bogie frame 1.
The twin coil spring 25 and cushion 14 assemblies described above also enable lateral movement in the suspension, responding transverserly to relative movement of the bolster 21 and the frame 1 in the transverse direction, and operating in conjunction with rubber buffers 44 (fig. 4) which are made secure to the damper mountings 41 and register with plates 45 afforded by the corresponding longitudinal bolster members 22. The effect, when compared with current suspension systems, is to give enhanced passanger comfort in the transverse axis. Both shoe 43 and plates 45 are made of a self-lubricating material of the known type.
The cross members 3 of the bogie frame 1 in correspondance of the wheel 8 also supports conventional shoe brake devices generally indicated at 42.
In contrast to conventional types of bogie, the frame 1 of the bogie according to the invention is relieved of vertical load generated by the weight of the vehicle body; instead, this preponderant load is distributed directly through the swing bolster to the axle boxes, in parallel with other longitudinal and transverse load components transferred from the axles to the body, likewise by way of the frame 1. Thus, when compared to the load bearing frames of conventional rail bogies, the bogie frame disclosed can be of reduced mass and has a guide function essentially. In construction, therefore, it becomes possible to utilize components of proven reliability, moderately innovative in embodiment, and accordingly to synergize the properties of the various parts of the bogie such that an optimum ratio is obtained between bending stiffness and shear stiffness in the connection between the two axles. As discernible from literature pertinent to the art field in question, in fact, the realization of near optimum values for this ratio reflects the maximum performance obtainable from a bogie with sprung axles, in respect of curve inscribability and dynamic stability.
With the type of connection adopted between vehicle body and bogie, namely the king bolt at centre, and shoes engaging directly with the body on both flank by way of self-lubricating bearing surfaces, the operations of lifting, rerailing etc. are made extremely simple, given the complete separation of "bogie unit" and "body unit". Such operations are complicated in conventional rolling stock with hanging bogies by the fact that the connections between car body and bogie are much more numerous; the detachment of the body and the second stage suspension springs, in particular, is especially time-consuming.
The effect of interconnecting the brake caliper assemblies 10 of different axles with longitudinal beams 5 is to lighten the two cross members 3 of the bogie frame 1, which otherwise would have to sustain the entire thrust of braking stresses, dictating bulkier proportions and the addition of considerable weight to the frame. Moreover, with a view to future developments of the bogie according to the invention within the sphere of ultra high speed travel, this same expedient will permit of mounting three disk brakes per axle and thus of upgrading the braking system.
Variations and/or modifications can be made to the bogie for rolling stocks according to the present invention, without departing from the scope of the invention itself.

Claims

A rail bogie, in particular for high speed rolling stock, comprising a frame (1) associated with two wheel sets (6), each comprising an axle (7) with a pair of keyed wheels (8) and means for pivotally supporting said axle, a swing bolster (21) carrying a vehicle body, and means for connecting together the frame, the bolster and the wheel sets, characterized in that the swing bolster (21), supporting the weight of the car body, rests directly on the wheel sets (6) by way of elastic supports; and in that the bogie frame (1) comprises two parallel longitudinal members (2) rigidly interconnected by two cross members (3) each comprising two sections (3a, 3b) articulated with one another by way of a ball joint (4).
A rail bogie as in claim 1, wherein the two ball joints (4) of the two articulated cross members (3) are disposed symmetrically on either side of and in diagonal alignment with the centre of the bogie frame (1), such that when a skew length of track is encountered by the bogie, the two wheels (8) of each set (6) remain permanently in contact with the respective rails whilst the frame retains rigidity in every other plane of action.
A rail bogie as in claims 1 and 2, wherein said means for pivotally supporting the axle (7) of each wheel set comprises a pair of axle boxes (11) with integral brackets (13), and wherein each of said elastic supports comprises a pair of coil springs (25) and a damper strut (30) located between said swing bolster (21) and each of said axle boxes (11) each of said coil spring being coaxially mounted about tubular seats (15, 15a) formed on each longitudinal member (22) of said swing bolster (21) and on each bracket (13) of said axle boxes with elastic cushions (14) placed therebetween.
A rail bogie as in claim 3, wherein each elastic cushion (14) comprises two metallic annular elements (26) facing respectively to the coil spring (25) and to the relative tubular seating (15, 15a) and an elastomeric annular element (27) sandwiched between the metallic elements.
A rail bogie as in preceding claims, wherein the axle boxes (11) and the longitudinal members (2) of the bogie frame (1) are connected by means of pins (16) bolted rigidly to and projecting from the longitudinal members, in conjunction with flexible mountings (17) of "Silentblock" type embodiment ensheating the pins and accommodated internally of the tubular seatings (15) afforded by the axle box brackets (13).
A rail bogie as in preceding claims, wherein the swing bolster (21) is fitted with self-lubricating shoes (43) on which to rest the vehicle body and a rigidly associated central socket (24) bu which a king bolt rigidly associated with the body is rotatably accommodated.
A rail bogie as in preceding claims, further comprising transverse suspension means operating between the bogie frame (1) and the swing bolster (21), each comprising a flexible buffer (44) secured to a mounting (41) rigidly associated with a central section (2a) of each longitudinal frame member (2), and a damper strut pivotably anchored to the mounting (41) at one and and to the central socket (24) of the bolster at the other end.
A rail bogie as in preceding claims, further comprising two longitudinal beams (5) disposed parallel with and symmetrically on both side of the longitudinal axis of the bogie, each of them connecting a pair of brake units (10) mounted on one side of the axles (7), to the end of supporting the relative braking stresses.