GB2132952A - Articulated railbus of lightened construction - Google Patents

Abstract

An articulated railbus consists of two, or at most three, carriages (1) coupled together by means of a special semi-permanent coupling consisting of a draw-hook device (3) permitting full angular displacement between the carriages in a vertical direction but limiting transversal deflection of the carriage ends to a predetermined delta-value. The chassis supporting the individual carriages are carried on two axles (2) each provided with a pair of wheels. An underfloor-mounted driving mechanism (4) drives one of the wheel axles (2) by way of propeller shafts (5). This driven wheel axle (2) is coupled to the wheel axle (2) of the adjacent carriage by way of further propeller shafts (6) symmetrically arranged to the draw- hook device (3) linking the two carriages. The body or coach of the rail bus is advantageously built from elements of a road bus body. <IMAGE>

Description

SPECIFICATION Articulated railbus of lightened construction The invention concerns an articulated rail bus of lightened construction forming a train-set consisting of two, possibly three, two-axled carriages wherein the ends of the carriages are driven and are coupled together in such a way that the driving mechanism mounted under one of the carriages drives the pair of wheel-axles placed under the coupled ends of carriages, and tractive gear located between said pair is such as to facilitate a) the rounding of bends by the carriages, b) the mutually independent displacement of carriage ends along a vertical axis, i.e.

mutually independent angular displacement about their longitudinal axes and their alignment on an inclined section of the rail track in such a manner that transverse movement of the carriage ends is restricted.

According to the invention, further advantages are derived from the fact that the cardan or propeller shafts coupling the driven wheel-axles are arranged symmetrically about a fulcrum, and therefore the angular excursions of the Cardan joints are favourable, i.e. approximately identical.

In the past decade the worsening of the energy crisis has promoted the development of railway vehicles of low power consumption particularly adapted for branch-line traffic. In the development work, attention had to be paid to rail safety, to the weight of the undercarriage and body, optimisation of passenger intake capacity, absorption of impact forces in the plane of the under-carriage, arrangement of the drive mechanism and the length of the carriage.

The known, earlier developed rail vehicles were initially two-axle vehicles wherein one of the axles was the driven axle and a mechanical driving construction was built in. To increase the passenger transport capacity, the length of the passenger carriages had to be increased. This caused an increase of the weight of the vehicle which in turn disadvantageously affected the magnitude of the permissible load exerted on the track by the axle weight. To avoid the danger of a concentrated dynamic effect, i.e. exceeding the permissible axle load, three or four-axled bogies were applied. This improved the rolling characteristics of these vehicles which, with extra coaches coupled to them, developed into light trains.

After the second world war the railway companies in the industrially advanced countries endeavoured to modernise the railways, introduce or extend electrification and developed vehicles with larger tractive capacity. This trend has also been adapted by less developed countries, within their limitations, and led to the formation of motor trains for branch line and suburban passenger transport. The energy problem led also to an increased demand for light motor coaches with underfloor drive mechanisms.

The main features of this kind of railway vehicle are low axle load and light construction, making it possible to incorporate light engines of lower power rating developed from road engines for railroad traction. Currently, light vehicles of various types are mass-produced in a number of countries. These motor coaches are, generally, narrow gauge vehicles but there are also vehicles for standard or broad gauge rail application. The drive mechanism is always underfloor to maximise passenger capacity.

Diesel engines developed from mass-produced road vehicle engines are generally flanged to the drive mechanism. The power transmission is diesel mechanical or hydromechanical adapted to branch line or mountain traffic, orto a lesser extent to diesel-electric traction in suburban traffic.

An articulated railway vehicle developed with regard to the various aspects of the problem de scribed above is described in GB-PS 1,531.565. The railway wagons described therein form a train wherein adjacent frames or chassis are coupled together at their ends by means of centrally posi tioned articulated construction arranged in a com mon truck. The coupling means for linking the frames or carriages to one another are provided with thrust-transmitting shock absorber bumpers fitted to the end of the wagons. Between the abutting sides of the undercarriage parts a curvature is formed, thus the gap between the frames or carriages is reduced and detecting means effective during rounding a bend detect any exceeding a predetermined de crease in the gap of the bend of the track.This detector transmits the thrust between the frames on the bend of the track, and is the most important part of the system. It is essentially a thrust bar mounted at the end of the carriage frame in such a way that it is movable between an operative and an inoperative position relative to buffers therefore it always bumps against the thrust-transmitting shock absorber on which a largerthan permissible thrust force acts.

GB-PS 1,457,964 describes an articulated rail wagon construction the chassis of which consists of a plurality of parts linked together by universal joint types of couplings, thus permitting both horizontal and vertical relative movements between the cou pled parts. The coupling mechanism is located in the plane of the central longitudinal vertical plane of the wagon. The free ends of the individual undercarriage parts or frame ends are supported by load-bearing (suspension) mechanisms held together by a slide bearing with the aid of a common supporting frame bearing against the wheel axles. Amongstthe indi vidual parts of the undercarriage between the under frame and the corresponding part ofthe undercar riage another coupling element is interposed in a horizontal plane.Also connection fittings are mounted acting on all parts of the carriage frames thereby transmitting forces from the corresponding suspension mechanisms that can change the vertical component of the pressure exerted in the corres ponding slide blocks. It follows from the very nature of this design that the various coupling elements, supporting mechanisms etc. considerably increase the weight of the vehicle.

German Published Application No. 2, 256,764 describes a three-part articulated train wherein the middle section consists of an articulated block the two outside parts of the carriage frame being supported on the extremities of two-shafted bogies (rotatable bases) and at least one door is arranged in the middle section. The wheels of the articulated block (the diameters of which, as known per se, nearly equal the height of the carriage) are developed in form of a shaftless annulus or wheel-rim.

The door in the block of articulation is located in such a way that alighting from the train is over one of the wheel rims. The ends of the articulated block are linked by a respective transverse horizontal guide-bar outer carriage parts while each guide bar is coupled on the one hand to the corner points of the outer carriage parts and on the other hand to guide slides located inside the articulation block. The guide slides can move on guide rails in a direction which is oblique relative to the longitudinal axis of the carriage. The two outer carriage parts are linked together at the middle of the roof by a coupling pin passing through the roof and moving in the same direction, the pin being journalled on a spring bearing extending beyond the articulated block. The pin has at least one pair of guide rollers through the block.Between the guide rollers a guide rail rigidly fastened to the top of the articulated block is slidable in a direction inclined to the longitudinal axis. The passing of the train around a bend of the rail track is assured by a cradle segment mounted on the individual bogies, therefore the inclination of the bogie is variable as a function of the travelling speed.

The drawback of this solution is that the bogies and cradle-segments quite considerably increase the weight of the vehicle.

A technical solution for guiding and directing railway carriages negotiating sharply curved bends of a rail track is described in Hungarian Patent Specification 161,582, according to which the train set comprises at least two rail carriages linked together at their contiguous ends. The linkage consists of one or more rigid bar(s) jointed to the carriage in such a fashion that the bars are fixed by universal joints at a predetermined distance from the articulated joint in the longitudinal direction and at least one pair of wheels is pivotally suspended on the rigid bars.

British Patent Specification No. 1,368,640 describes a similar solution relating to a rail-bound articulated vehicle. According to this solution the running gear is on the one hand connected with the aid of a swing bar mounted on the running gear guiding the carriage in the longitudinal direction and on the other hand is connected with a bearing. One end of one of the bars, which an articulatedly arranged mounting ensuring longitudinal guidance is located, fits to the laterally longitudinal support of the undercarriage of the other coach and it is also provided with an obliquely positioned guide spring which is turnable around a vertical pin. The guide mechanism consists of three rigid bars linked together into a triangle and fitted to the bearing of the running gear.The upper part of the bars is linked via a bearing to the vertical pin and to the obliquely oriented guide bar.

French Published Application No. 2,413,991 describes a railbound articulated vehicle wherein for transmission of the traction power at least one pivot pin is mounted between two carriages whilst a resilient journal servesforthe reduction of the load on axle.

All the systems described above are suitable for long-distance trains and can only negotiate bends of relatively large radius of curvature but do not solve the problem of the reduction of axle loads.

Aremarkablesolution of the problem of guiding of known articulated rail-bound vehicles on curved sections of the rail track is described in British Patent Specification No. 1,333,132. The undercarriage or chassis of a train are coupled together by axial ball joints arranged in pairs. Each free end of each chassis or undercarriage is linked to running gear and two linked chassis ends rest on a common bogie in which a pair of pivot pins are jointed to one another about a vertical axis. One of the pins of the pair of pivot pins can be shifted in the direction of the longitudinal axis of the chassis. On each of the bogies there is a slidable bearing guide for coupling the pivot pins so as to be displaceable in a longitudinal direction of the chassis.In addition a further pair of pivot pins is mounted on the chassis the pins of which are co-ordinated to each of the chassis but their distance from the first pair of pins is constant. A vertical shaft runs through the centre of ball-andsocket joints and a mounting is formed on the bogies to keep each pin of the second pivotally moving pairs of pins at identical distances from the vertical axis of symmetry of the bogie. This is identical with the distance of both pins of the various pivot pin pair as measured on the axis. The object of this construction is to provide a symmetric guidance of the wheel-axles.

The main disadvantage of solutions aiming to increase the length of two-axle vehicles with light coach bodies is that to ensure a railway carriage with a length of 20-24 m bogies or rotary frames have to be provided. The rotary frames or bogies considerably increase the deadweight of the railroad vehicle.

The increased weight has to be distributed over for axles which is an advantageous arrangement but has the inherent disadvantage that the specific net weight of the railroad vehicle is further increased and this necessitates the application of a drive mechanism of higher power rating. Because of this and because the construction of the vehicle must be reinforced a further increase in weight is thus caused. Furthermore, with the increase of the length of the vehicle the width of vehicle had to be reduced because the vertical section of the permanentway narrows when the train negotiates a bend, therefore the solutions described before cannot be successful iy applied in branch lines and on tracks with sharply curved sections of the railtrack.

It follows that to build a light railbound articulated rail bus of maximum passenger capacity that can be used on railtracks of light or 'loose' construction and/or of varying sharp curves, the rail bus having optimum traction power, optimum axle load, minimum frame or chassis weight requires a compromise or reconciliation of contradictory and mutually adverse conditions. It is also an important factor that the costs of the construction of relatively long vehicles and/or two coupled shorter vehicles related to the same number of passengers carried, are higher than the cost of building an articulated railbus.

The aim ofthe invention is to provide an articulated rail bus of lightened construction in place of the known railway vehicles of deadweight-increasing underframes or chassis and bogies and of increased number of axles, the improved railbus having fewer wheel axles, lightened coaches and capable of travelling with full safety on sharply curved sections of rail tracks which is fitted with a system of the simultaneous equalisation of the lateral and vertical swing and the manufacturing costs of which permit the marketing of it worldwide at a competitive price.

The aim of the invention is sought to be achieved according to the invention by a railbus of light carriage body frame mounted on two optimally short rail under-carriages or chassis, the body according to a preferred embodiment of the invention being the body of road bus. Two pairs of axles are fitted under the individual carriages of the railbus whereby the axle load is reduced. One pair of axles of the carriages are the driven wheel-axles and the carriage-ends that are contiguous to the driven axle are coupled together and a free gangway between the passenger compartments is provided.

The railbus according to the invention consists of preferably two two-axle carriages (but it may also consist of three carriages) wherein the coupled ends of carriages are supported by one pair of driven wheels and the leading ends of the carriage are supported on one pair of running wheels. The driven and running wheels journalled in roller bearings are coupled to the body of the carriage by means of a per se known longitudinal tie rod. Steel coil springs located at both sides of the axles are housed in cast iron bearing cases or boxes and the upper end of the tension coil springs are located in helical spring plates mounted on the undercarriage. The elastic transversal movement between the wheel pairs of the body of the carriage is secured by the flexural load on the coil springs (the so-called 'flexicoil' strain).The vertical and transversal swing of the body of the carriage are damped by means of shock absorbers.

The special so-called semi-permanent, coupling between the carriages is achieved by a draught construction permitting a mutually independentvertical flexure of the two coupled carriage bodies. The same construction limits the transversal displacement of the ends of carriages to an extent which is sufficient to allow for relative lateral excursions of the ends of carriages. Both ends of the railbus are fitted per se known light draw bars and buffers.

The invention is further described, purely by way of example, with reference to the accompanying drawings, wherein; Figure 1 illustrates in side elevation the means for coupling and driving a railbus consisting of two carriages according to the invention; Figure 2 is a schematic bottom plan view of the coupling of the ends of carriages with their lateral excursions; Figure 3 shows diagrammatically and on an enlarged scale the coupling between two carriages; Figure 4 is a schematic diagram of the articulated joint and the wheel drive; and Figure 5shows a railbus according to the invention and consisting of three carriages with bow or draught means and a coupling device between the carriages, and a drive mechanism.

According to a preferred embodiment of the invention a railbus comprises an undercarriage on which a body utilising the body 1 of a bus for public road transport is mounted.

The body 1 may, of course, be of another design.

Only two pairs of wheels are provided under each carriage of the railbus train. The coupling between two carriages consists of a draw-hook device 3 permitting the mutual aligment and angular displacement about the longitudinal axis of the carriages and their adjustment according to the angle of inclination of sloping or curving sections of the railtrack in such a way that the transversal displacement of the ends of the carriage is restricted.

The drive means consists of a driving mechanism 4 located under the floor of one of the carriages of the railbus, and may expediently be an electric or diesel-electric engine coupled by a propeller shaft 5 with universal joints to the driven wheel axle 2 and by an identical propeller shaft 6 to the driven wheel axle 7. of the adjacent carriage.

Shafts 6 with universal joints coupling the driven wheel axles 2,7 are symmetrically arranged around a central fulcrum, hence their angular excursions are favourable, i.e. are approximately identical.

Figure 4 illustrates that each of the coupled ends of the articulated rail bus according to the invention is supported by a corresponding pair of driven carriage-wheels and each of their leading ends is supported by a pair of travelling or running wheels 9 (Figure 4). The driven wheels 2 are journalled on roller bearings and the travelling wheels 9 are linked to the undercarriage by respective longitudinal tie rods transmitting the longitudinal forces via respective wear-resistant rubber couplings. The draw-hook device 3 fitted with a vertical pin 8 links the two carriages by means of coupling bars 11 and ball joints 10 in such a manner that the coupling bars 11 permit horizontal displacements within limits corresponding to a predetermined delta-value.This special so-called semi-permanent coupling makes it possible for the draw-hook device 3 as a rigid system to permit mutually independent vertical springing of the bodies 1 and their angular displacement about the longitudinal axis of the carriages.

The horizontal deflection of the ends of carriages relative to one another is limited but is still sufficient to ensure the safe travelling of the railbus also along sharply curved bends of a rail track.

Compared with the known and generally successful designs for similar objectives, the articulated railbus according to the invention has important advantages: - until now, nowhere in the world has an articulated railbus been built; - due to the articulated construction, the bogies which increase the weight of the rail bus have been obviated, and at the same time, the substantially lower weight of the road bus-type (or similar) body 1 opens the way to the application of underfloor driving mechanisms 4 with lower power rating and to an increase of the passenger compartment space.

Due to the articulated construction the vehicle may also be built in multipart embodiments as illustrated in Figure 5.

Due to its light weight, the articulated rail bus according to the invention in its two-coach embodiment is equally suitable for travelling in full safety both on mountain and flat-land rail tracks and even on tracks with sharp curved bends, e.g. where the maximum permitted length of the carriage is only 14m. Due to the lower axle load the vehicle according to the invention can also be used on existing tracks with limited weight carrying capacity without reinforcement of the track or permanent way.

Due to the relatively short carriage length, a particularly light-weight body can be mounted on the undercarriage thus a superlight vehicle could be created which, with increased width of carriage (including passenger capacity) can be manufactured in mass production.

A substantial advantage is that the vehicle can be driven in both directions with identical traction characteristics due to the disposition of the axes, because the draw-hook device 3 transmits longitudinal forces by driving the axle under the fulcrum or ball joint. Thus there is no need for a delta-track or for a turntable at the termini.

Claims (3)

1. Articulated rail bus of lightweight construction consisting of two or three carriages, comprising a driving mechanism mounted under the floor of one of the carriages, propeller shafts for coupling said mechanism to an axle of a wheel pair of the same carriage, the said driven axle of the adjacent carriage by propeller shafts which are arranged symmetrically about the fulcrum of a draw-hook device that couples the said carriages together.

2. Articulated rail bus of lightweight construction consisting of two or three carriages, comprising a draw-hook device for coupling the ends of the carriages together the said draw-hook device being effective to permit a full vertical deflection of the carriage ends relative to each other but to limit their relative transversal deflection.

3. Articulated rail bus substantially as herein described with reference to and as shown in the accompanying drawings.