WO2002085650A1

WO2002085650A1 - Apparatus for adapting road vehicle to provide road and rail capability

Info

Publication number: WO2002085650A1
Application number: PCT/GB2002/001758
Authority: WO
Inventors: Bryce Randall
Original assignee: Harsco Track Technologies Ltd
Priority date: 2001-04-19
Filing date: 2002-04-19
Publication date: 2002-10-31
Also published as: GB0318328D0; GB2390066B; GB0109668D0; GB2390066A

Abstract

A dual-purpose road/rail vehicle and apparatus for adapting an existing road or utility vehicle to provide it with a road/rail capability. Axles carrying rail guide wheels may be fitted to the front and rear of a road vehicle and deployed, is swung down to engage the rails by mechanisms such as a manual lever arrangement or a hydraulic pistion and cylinder. Particularly but not exclusively for use with vehicles having an independent road wheel suspension system (10, 42), for example a MacPherson strut or similar, in this invention, a set of rail wheels (21) are supported with respect to the vehicle (100) by support means (5, 5') which extends beneath the suspension system (10, 42) and can move between a first position (Fig 2A) adjacent a portion of said suspension system and a second position (Fig 1A) in which the support means clears said suspension system for action with respect to the road wheels (1'). When the support means is in the first position and the railway wheels are deployed, the support means engages the suspension system and the weight of the vehicle is carried via the suspension system, the support means and the rail wheels.

Description

APPARTUS FOR ADAPTING ROAD VEHICLE TO PROVIDE ROAD AND RAIL CAPABILITY

This invention relates to a vehicle, in particular to a dual-purpose vehicle adapted to be driven on roads or on rails. The invention also relates to apparatus for adapting an existing road vehicle to provide it with a road/rail capability. By the term road vehicle, there is meant herein a steerable vehicle generally suitable for road use but including also a utility vehicle primarily intended for use in the field or over rough terrain, farm tracks and like

Dual purpose road/rail vehicles are generally known. By way of example, they might be used for the maintenance, repair and building of railway lines, sidings and bridges.

Thus, US 4167142 discloses a vehicle for moving rail cars which is adapted for travel on a railway track or on a road. The vehicle has raisable and lowerable ground wheels which are configured in a triangular arrangement, the front steerable wheels being widely spaced apart and outboard of the front rail wheels, the rear wheels being inboard of the rear rail wheels and non-steerable.

A railway wheel conversion apparatus for road vehicles is disclosed in US 4488494.

This apparatus comprises a support arm mounted between the leaf spring of the road vehicle and a bumper extension member. A railway wheel is pivotably connected to the extension member. A piston connects the railway wheel and the extension member and is used to move the railway wheel from a retracted, non-rail contacting, position to an extended rail contacting position, thereby lifting the vehicle's wheels from the supporting surface

US 4497257 and US 4878436 both disclose vehicles which have non-retractable railway wheels and retractable road wheels, the road wheels being driven by virtue of an endless belt or chain powered by the railway wheels.

In addition, we have proposed various apparatus for adapting an existing general purpose or utilty road vehicle to have a dual road/railtrack capability in which axles carrying rail guide wheels are fitted to the front and rear of the vehicle and are deployed, ie swung down to engage the rails by mechanisms such as a manual lever arrangement or a hydraulic piston and cylinder, and in which the road wheel suspension is kept operable while the rail guide wheels are deployed. As a result, it is not neccessary to provide a separate suspension system for the rail wheels.

However, such proposed apparatus is not suitable for all types of road vehicle, in particular some vehicles having independent front suspension where, for safety reasons, it is important to maintain the vehicle manufacturer's specification for that suspension

It is an object of the invention to provide a vehicle which is provided with a suspension system which provides equal or similar ride characteristics in both rail and road modes and whose steering geometry is not unduly altered by the conversion between road and rail use. Another object is to provide adaptation apparatus which enables the road wheel suspension to be used whilst the rail wheels are deployed (so avoiding the need for a separate rail wheel suspension system) but without comprising the ride and steering characteristics of the road vehicle.

Yet another object is to provide a dual road/rail vehicle and apparatus for adapting a road vehicle to have a rail capability which provides a relatively rapid and simple changeover from road to rail and vice versa

According to one aspect of the invention, there is provided a vehicle for travel on road and on rail track, the vehicle comprising a set of road wheels coupled to the vehicle by suspension means, and a set of railway wheels for being deployed for engaging the rail track and retracted for road use of the vehicle, the railway wheels being supported with respect to the vehicle by support means which extends beneath the suspension means and which can move between a first position adjacent a portion of said suspension means and, when the railway wheels are deployed, engaging said portion for the vehicle to be supported with respect to the rail wheels via the support means and the suspension means, and a second position in which the support means clears said suspension means for action with respect to the road wheels.

Preferably, the support assembly comprises two arms extending longitudinally from the vehicle and supporting said railway wheels at their distal ends, said arms being pivotable at their proximal ends about substantially vertical axes and said suspension means comprising two suspension bars for respective road wheels, said suspension bars extending transversely from the vehicle and being inclined downwardly towards their distal ends, wherein said arms extend beneath said suspension bars, engage on underside of said suspension bars in said deployed condition and are disengaged from said suspension bars in said retracted condition.

This results in similar ride characteristics in the road and rail modes.

The suspension means may, for example, comprise spring means such as leaf springs, compression springs and the like, air suspension means or other suspension means known to the skilled addressee.

Other preferred features are defined in the dependent claims. The point-of-action of said suspension means, in this specification, is intended to refer to the point at which said resilient means is attached to an axle attached to the wheel. Thus, vertical reciprocal motion of the or each road wheel is dampened by respective resilient means.

Preferably, the arms support said suspension means when the railway wheels are in the extended position, whereby vertical motions of the front railway wheels are damped by said suspension means.

In one embodiment, front railway wheels are connected to the vehicle by a pair of arms which are located at a position below said suspension means and, in the retracted position of the front railway wheels, are located close to the pivot axis of suspension arms whereby vertical movement of the suspension arms is unimpeded by the arms as is movement of the front road wheels.

Each set of railway wheels, respectively front and rear, may be located on a single common axle.

The movement of the rear railway wheels, between extended and retracted positions may, for example, be effected by actuation means such as pistons, pulleys or other means well known to the skilled addressee. The movement of the rear railway wheels may also be effected by virtue of a pair of arms which extend below rear suspension means and which pivot to move the those railway wheels between the extended and retracted position.

In a preferred embodiment the arms are connected to a rail axle pivot rod, an end of each arm being slidably received thereon, by virtue of a bush, bearing or the like. The rail axle pivot rod is preferably parallel to the or each front axle.

The arms are preferably pivotable in a direction transverse to the longitudinal axis of the vehicle, which is to say the intended 'normal' direction of travel of the vehicle.

It is a further preferred feature that the vehicle comprises actuation means for the pair of arms so that the ends thereof can slide along the pivot rod to thereby effect rotation of the axle about the pivot rod so as to move the front railway wheels between the retracted and extended positions. Preferably the pivot rod and the axle are eccentrically linked.

Preferably, in the retracted position of the front railway wheels the pair of arms are inwardly inclined with respect to the longitudinal axis of the vehicle, the opposite being preferably true in the extended position of the front railway wheels.

The pivoting motion of the arms preferably occurs in a direction transverse to the longitudinal direction of the vehicle.

According to another aspect of the invention there is provided apparatus for adapting a road vehicle to have a dual road and rail capability, the apparatus comprising a pair of rail wheels and support means for being mounted to the vehicle for supporting the railway wheels with respect to the vehicle, said support means including two elongate members for being connected to the underside of the vehicle and extending beneath the vehicle road wheel suspension means, respective ends of the two elongate members being connected to support said railway wheels and being movable with respect thereto transversely between spaced apart positions for the elongate members to engage the suspension means and relatively closer positions for the members to clear said suspension means.

In order that the invention may be more fully understood, the invention will now be described, by way of example, with reference to the drawings in which: Figure A is a diagrammatical plan view of a vehicle according to the invention with wheels in retracted position;

Figure 1 B is a longitudinal part sectional view of the vehicle of Figure 1A; Figure 1 C is a front elevation of the vehicle of Figure 1 A;

Figure 2A is a plan view of the vehicle of Figure 1A with the wheels in an extended position;

Figure 2B is a longitudinal part sectional view of the vehicle of Figure 2A;

Figure 2C is a front elevation of the vehicle of Figure 2A;

Figure 3 is a diagrammatic perspective view showing the railway wheels in the deployed condition;

Figure 4 is a diagrammatic perspective view showing the railway wheels in the retracted condition; and

Figure 5 is a perspective view of part of apparatus for use in adapting a vehicle. The drawings illustrate one example of a John Deere GATOR (registered trademark) 6 by 4 utility vehicle which has been adapted to have a rail capability, ie so that it can be used on the road (or the field, rough terrain, farm tracks and so on) as normal but which also has rail wheels that can be deployed for the vehicle to be used on a railway.

As will be appreciated, the invention is not limited to the particular vehicle shown. However, it may not be applicable to all vehicles even if they may appear to be similar. Also, there are several models of the particular vehicle shown and the manufacturer may replace any of them with modified versions. Hence, as will be appreciated by those skilled in the art, this invention should be interpreted and applied having due regard to appropriate design principles so as to ensure safety and satisfactory vehicle handling characteristics.

Subject to the aforementioned different models and the possibility of future manufacturer's design modifications, further information concerning the particular vehicle illustrated is available through publications and inspection of actual vehicles, Such information is incorporated herein by reference.

The vehicle has a rear wheel drive, rack and pinion steering and what is called independent "spring over shock" single A-arm front wheel suspension. This is similar to what is also called single wishbone or Macpherson strut suspension. Each front wheel 1' is supported and stabilised by both a single wishbone or A-arm and a coil spring/shock absorber combination 41. The A-arm/wishbone is made up of a front and a rear suspension member. The front members are referenced 10a and 10b in the drawings - where it is not necessary to indentify a particular one of the front members, the reference 10 will be used. Each rear suspension member is referenced 42. Each front member 10 connected via a first pivot joint to the steering pin assembly (not shown) and via a second pivot joint to the underside of the vehicle body. From the first to the second pivot joint, the front suspension member extends in the direction transverse to the longitudinal centre line of the vehicle body and upwardly sloping. The second suspension member 42 is connected to the front member 10 near the wheel and via another pivot joint to the underside of the vehicle to the rear of the second pivot joint. The spring/shock absorber 41 (the Macpherson strut) is connected to the wheel end of the member 10 and extends up to the vehicle body above the steering pin.

The rear suspension characteristics of the vehicle are generally dependent upon the four non-steerable, driven rear wheels 1 , these wheels having pneumatic 'balloon' tyres.

To adapt the vehicle to have a rail track capability, the rear driven wheels 1 are provided with axle extensions (not shown) to make the wheel base equal to the width of the railtrack, i.e. so that, when the vehicle is used on a railway, the wheels lie over the respective rails and can contact them to drive the vehicle.

For a different vehicle, alteration of its rear wheelbase width may not be neccessary

At the rear of the vehicle, two rear rail wheels 31 are provided on an axle 32 When the wheels 31 are deployed, the driven road wheels 1 are not lifted from the rails. Rather, they continue to support the weight of the vehicle and to drive the vehicle as in road operation. The function of the wheels 31 is simply to maintain the wheels 1 aligned with the rails.

An axle 22 with two rail track wheels 21 is also connected to the front of the vehicle. As will be described in more detail later, the wheels 21 are supported by two longitudinal members 5, 5' which extend beneath the front road wheel suspension, ie below the front and rear suspension members 10 and 42 and are connected to the underside of the vehicle body, Each end of each member 5, 5' is connected by a ball joint so that the front ends of the members can move in towards one another and these members pass beneath the pivot connections between the members 10 and 42 and the vehicle body. Here there is sufficient room so that the members 5, 5' remain well clear of the suspension members 10 and 42. Thus the vehicle can be used on the road without interference between the rail wheels and the road wheel suspension, The ends of the members 5, 5' can also be moved outwards so as to lie beneath relatively low outboard ends of the respective suspension members 10a, 10b. Deployment of the rail wheels 21 and consequent raising of the members 5, 5' then tends to bring the members 5, 5' into contact with the undersides of the outboard ends of the members 10a, 10b and to lift these members along with the front road wheels. Respective plastics material pads (not shown) may be provided beneath the ends of the members 10 to buffer the contact between the members 10 and the members 5, 5'. The wheels 21 thus become non- effective but the front wheel suspension now acts through the members 10a, 10b and the members 5, 5' to the rail wheels. Referring in more detail to Figures 1A to 1C, there is shown a vehicle 100, which is provided with a set of six road wheels 1 and front and rear railway wheel assemblies 2, 3 respectively. The front railway wheel assembly 2 comprises a pair of railway wheels 21 rotatably mounted on an axle 22. Similarly, the rear railway wheel assembly 3 comprises a pair of railway wheels 31 rotatably mounted on an axle 32.

The front railway wheel assembly 2 further comprises two axially aligned elongate pins 24 mounted in parallel to the axle 22 and connected thereto at their outer ends by virtue of brackets 25. The inner ends of the pins are connected to a tubular member 200 which is connected to the axle by brackets 201 similar to the brackets 25. The brackets 25 and 201 provide an eccentric link between the pins 24 and the axle 22.

Attached to the pins 24 are arms 5, 5' which extend under the suspension system 4 associated with the vehicle 100 and, as can be seen, are mounted to the chassis or frame of the vehicle at points 51 , 51' significantly rearward of the suspension system 4, and within the bounds of the vehicle 100.

The front wheels 1 ' of the vehicle 100 are rotatably mounted to hubs incorporating steering pin assemblies (not shown). The members 10 are connected to the steering pin assemblies.. The suspension system 4 associated with the vehicle 100 seeks to dampen any vertical motion experienced by the wheels 1' and comprises resilient means 41 , in this case compression spring/shock absorber assemblies, and rear suspension arms 42 through which the wheel 1 is connected to the chassis of the vehicle 100.

Pivotably connected to the front of the vehicle, there is a manual lift mechanism comprising lever handle 202. Pivotably connected to the lever handle there is a downwardly extending member 203 with a ground contact plate 204 at its lower end. When handle 202 is swung down, plate 204 engages the ground and lifts the vehicle at the front. This enables the rail wheels to be engaged or disengaged from the track. Alternatively, instead of being operable to lift the vehicle, the lever handle could be so coupled to the axle 22 as to raise and lower the wheels, ie to the retracted and deployed positions as required. The rail wheels are locked in the deployed and retracted positions by suitable locking means. For example, when the axle 22 is raised above the pins 24 and 201 in the retracted state of the rail wheels, the axle is locked in place by being coupled to a linkage attached to the front of the vehicle chassis. For additional safety, when in the retracted inwards position, the arms 5,5' are located over ledges 205 fixed to the front of the vehicle chassis. The ledges could be formed by laterally extending portions 206 of plate 204m so that, when the plate is down, the arms 5, 5' are released for movement outwards if the vehicle is being put in its rail mode or, if the arms are moved inwards and the vehicle is being put in its road mode, the plate 204 can be lifted using lever 202 and the ledges 206 will then rise up also and engage and support the arms 5, 5'.

The arms 5, 5' are slidably mounted upon the pins 24 by a respective bush 52 or limited action ball joint bearing as shown best in figure 5. When the arms are in the outward deployed position, they are located by slotted plates 210 fixed to the pins 24

The rear railway wheels 31 are mounted on the axle 32 which, in turn, is eccentrically linked to a suspension arm 33 by brackets 35. The suspension arm 33 is mounted on the chassis or frame of the vehicle 100 and is connected to a piston/damper assembly 36. This assembly is operable to urge the rear rail wheels into engagement with the tracks when they are deployed. The assembly could be combined with or accompanied by a piston or other adjustable means (not shown) for deploying the rail wheels between their engaged and retracted positions.

Alternatively, there could be a manual lever arrangement (not shown) for this. It will be remembered that the rear of the vehicle does not have to be lifted to engage or disengage the rear rail wheels since these wheels are only needed to guide the vehicle. They do not support the weight of the vehicle.

In other embodiments, this may not be true. Namely, the rear suspension of the vehicle might be similar to the front suspension say and there may be required a support means comprising arms such as 5, 5' at the rear of the vehicle instead of or in addition to that at the front. The vehicle drive could be other than via the rear road wheels of course. In Figures 1A to 1C and 3, the railway wheels 21 are shown in their retracted position, i.e. the wheels 1 engage the supporting surface, the railway wheels 21, 31 being in their inoperable position.

Figures 2A to 2C and 4 show equivalent views to those discussed above but with the railway wheels 21, 31 in their deployed position so as to render the ground wheels 1 inoperable (identical reference numerals have been used). The arrows in Figures 3 and 4 show the slipping of the linkage (comprising a support road 22 and an eccentric link L) between the deployed and retracted conditions. It will be seen that in the deployed condition (Figure 3) the arms 5, 5' engage the underside of the suspension arms 10a, 42/10b, 42, at the point of action of the springs 41 whereas in the retracted condition (Figure 4) the arms 5, 5' are spaced apart from the suspension arms.

Considering the actuation of the front railway wheel assembly 2 first, in order to extend the front railway wheels 21 from their retracted position (Figures 1A to 1C), the arms 5, 5' are pivoted about their respective points of attachment 51 , 51' to the chassis or frame of the vehicle 100. Such pivotal motion causes the distal end of each arm 5, 5' to slide along the pivot rod 24. Obviously, given the geometry of the system the arms 5, 5' have a maximal 'effective length' when they are aligned parallel to the longitudinal axis of the vehicle 100, the converse being true at the extremes of arm 5, 5' travel (the 'effective length' (EF) is herein defined as the vector component of the arms 5, 5' in the direction of the longitudinal axis of the vehicle 100). The maximal EF of the arms 5, 5', together with the eccentric link between pivot rod 24 and axle 22, causes the wheels 21 to 'flip' from a retracted position to the extended position shown in Figures 2A to 2C.

In the extended position of the wheels 21 , the arms 5, 5' are outwardly inclined with respect to the longitudinal axis of the vehicle 100. This has the effect of causing the arms 5, 5' to extend below the suspension system 4. Indeed, a point of each arm 5, 5' supports the suspension system 4 when the railway wheels 21 are in the extended position. This ensures that vertical motions experienced by the front railway wheels 21 are dampened by the suspension system 4. As can be seen from the drawings, the arms 5, 5' support the suspension system 4 at the point at which the suspension arms 42 and resilient means 41 act on the axle 10. In this case, each arm 5, 5' acts as a beam which transfers vertical displacements experienced by the railway wheels 21 to the suspension system 4. Obviously, the suspension system 4 damps the vibrations or oscillations and, consequently, provides a smooth ride characteristic.

The position of the arms 5, 5' when the front railway wheels 21 are extended should be contrasted to their position when the wheels 21 are retracted (Figures 1A to 1C). In the latter case, the arms 5, 5' are inwardly inclined with respect to the longitudinal axis of the vehicle 100 and do not contact or support any part of the suspension system 4. As the arms 5, 5' are inwardly inclined they do not interfere with the normal running of the vehicles front road wheels 1'. Moreover, the arms 5, 5' do not interfere or upset the operation of the suspension system 4 and, consequently, do not affect the ride characteristic or steering of the vehicle 100. The rear railway wheel assembly 3 is moved from a retracted condition (Figure 1B) to an extended condition (Figure 2B) by the suspension arm 33 and the eccentric link provided therefrom to the axle 32 by the bracket 35. Actuation of the piston 36 causes the wheel 31 and bracket 35 to move eccentrically with respect to one another and, in so-doing causes the wheels 31 to 'flip' into their extended state. A reverse operation is also possible. Piston 36 can be replaced or augmented by a spring damper suspension strut.

In use, a driver will drive the road vehicle 100 (Figure 1A to 1C) from the road to a set of railway tracks 60, ensuring vertical alignment of the railway wheels 21 , 31 therewith. Upon actuation by the driver of the arms 5, 5' and pistons 33, the railway wheels 21 , 31 will move into contact with the rails 60, thereby lifting the road wheels 1 from the ground (Figures 2A to 2C). The vehicle 100 is then ready to be run on the railway tracks 60.

Whilst it is preferred to use the same engine in both transport modes, a second engine can be used for that purpose. The engine may also be used to provide power for associated such as a turntable/lift mechanism (not shown) that can be extended down beneath the vehicle to lift the vehicle up and enable it to be turned about the axis of the turntable. This enables a vehicle driven onto a rail track crosswise to be turned and aligned with the track. The rail wheels can then be deployed, the turntable/lift retracted, and the vehicle driven off along the track. The power for the vehicle may be electrical or by a combustion engine. Also, the vehicle 100 may comprise one or more 'pick-ups' to take electrical power from the dedicated lines that run along-side, underneath or over railway lines.

As can be seen from the drawings, the eccentric link, afforded the vehicle 100 by the brackets 25, 35, ensures that in either condition of the wheels 21 , 31 they are securely restrained. For example, the point of attachment of the bracket 25 to the arm 5 is further forward, with respect to the longitudinal axis of the vehicle 100, than its point of attachment to the axle 22. A similar arrangement is present at the rear of the vehicle 100, where the point of attachment of the bracket 35 to the piston 33 is further rearward than the point of attachment of the bracket 35 to the axle 32.

It will be understood that actuation of the arms 5, 5', to thereby convert the vehicle 100, may be effected by any suitable means, for example hydraulic or pneumatic pistons, endless chains or belts, rack and pinion systems, electrical and electronic actuators and the like. Also, the piston 33 at the rear of the vehicle 100 may be replaced by any suitable means, such as those described above.

The description, with regard to the drawings, has shown a vehicle 100 with the suspension system 4 comprising compression springs 42 but other suspension systems could be used. For example, air suspension systems could be used, an air bag providing the resilience for the system. In this case the bag would be supported by a member through which displacements of the wheel are transferred to the bag. In the deployed condition of the wheels the arms would support the underside of that member so as to damp any vertical displacements experienced by the railway wheels.

Furthermore, the system can also be used on a vehicle with a different kind of suspension, possibly a double wishbone suspension or one with multiple links, or on a vehicle with non-independent suspension. For example, a vehicle with an axle and leaf springs. In this case a minor modification may be required as leaf springs are normally oriented parallel to the longitudinal axis of the vehicle. The point of attachment of the wheel axle to the leaf spring will be supported by the arms when the railway wheels are in the extended position.

Whilst the above description refers to a vehicle 100, the invention is also applicable to the conversion of a road going vehicle to a dual purpose vehicle. It will be readily understood by the skilled addressee that the rail components; arms 5, 5', front rail wheel assembly 2 and rear rail wheel assembly 3 could be readily installed on any road going vehicle. Because the arms 5, 5' extend below the suspension system 4, installation is relatively simple. Also, as there is no alteration to the steering geometry of the road vehicle installation can be carried out quickly.

The vehicle 100 as shown in the drawings is a relatively small utility vehicle, however, the principles of the invention may be applied to a larger vehicle. In such a case it may provide necessary to use arms similar to those used on the front of the vehicle 100 on the rear railway wheels 31. The rear arms would similarly support the rear suspension means with the wheels 31 in their extended position.

Claims

1. A vehicle for travel on road and on rail track, the vehicle comprising a set of road wheels coupled to the vehicle by suspension means, and a set of railway wheels for being deployed for engaging the rail track and retracted for road use of the vehicle, the railway wheels being supported with respect to the vehicle by support means which extends beneath the suspension means and which can move between a first position adjacent a portion of said suspension means and, when the railway wheels are deployed, engaging said portion for the vehicle to be supported with respect to the rail wheels via the support means and the suspension means, and a second position in which the support means clears said suspension means for action with respect to the road wheels.

2. A vehicle according to Claim 1 , wherein the support means comprises two arms extending longitudinally from the vehicle and supporting said railway wheels at their distal ends, said arms being pivotable at their proximal ends about substantially vertical axes and said suspension means comprising two suspension bars for respective road wheels, said suspension bars extending transversely from the vehicle and being inclined downwardly towards their distal ends, wherein said arms extend beneath said suspension bars, engage on underside of said suspension bars in said deployed condition and are disengaged from said suspension bars in said retracted condition.

3. A vehicle according to Claim 2, wherein said support assembly further comprises a hinged linkage connected between said distal ends of said arms and carrying an axle of which said rail wheels are mounted, said axle being movable between a lower position beneath said arms in said deployed condition and an upper position above said arms in said retracted condition.

4. A vehicle according to Claim 3, wherein said hinged linkage is mounted on a support rod carried on the distal ends of said arms, said distal ends being slidable along said support road to engage and disengage said underside of said suspension bars.

5. A vehicle according to any preceding Claim, wherein said arms are inclined towards each other in said retracted condition.

6. Apparatus for adapting a road vehicle to have a dual road and rail capability, the apparatus comprising a pair of rail wheels and support means for being mounted to the vehicle for supporting the railway wheels with respect to the vehicle, said support means including two elongate members for being connected to the underside of the vehicle and extending beneath the vehicle road wheel suspension means, respective ends of the two elongate members being connected to support said railway wheels and being movable with respect thereto transversely between spaced apart positions for the elongate members to engage the suspension means and relatively closer positions for the members to clear said suspension means.