The present invention further relates to a means for coupling together two vehicles, in particular two bimodal vehicles.

Bimodal freight vehicles have been in existence since the 1960s, notably RoadRailer, which originated in USA (RoadRailer Inc). Since then, conversions of conventional road vehicles (eg Land Rover, Permaquip) have become widely available to enable maintenance personnel to travel quickly and conveniently to work-sites, operate as small locomotives and operate as machines such as cranes.

Bimodal vehicles and trains are different from container trains and piggyback trains in that in at least one mode, the wheels for the other mode are often carried, and in that there is no second load-bearing frame under the vehicle when it is operating in at least two of the modes.

Bimodal vehicles are not limited to travelling on road and rail, and may travel in other modes which may include maglev, water etc.

Bimodal freight vehicles and systems have been slow in adoption. This appears mainly to be associated with significant restrictions to their use and effectiveness: These disadvantages include: long trains of bimodal vehicles when on rail have been necessary to justify the high cost of the locomotives needed to haul them;

the formation and dispersal times for long bimodal trains have been excessive in relation to total transit times and a restriction on their ability to deliver'just-in-time' ; bimodal trains are uni-directional, so restricting their ability to reach private lines and use diversionary routes to avoid congestion; the mass of a locomotive is needed to allow it to have sufficient power and grip to haul large trains, but wastes energy and restricts the range of routes open to the train; management and/or return of the second-mode running gear (ie rail bogie or road wheels etc) when not in use has always been a problem; the trailer parts of the system are often of diverse ownership and manufacture, so cable and pipework communications through the train are often difficult to make reliable; braking reliability and progressive action is limited by slow propagation of air pressure down the train; in-train security and awareness of cargo condition on other modes are more limited than on road where there is typically one driver per vehicle; the structural strength of the trailers in a long train has to be significantly greater than for road operation alone ; the harsh motion inputs from the steel wheel/rail interface are often insufficiently absorbed, so they become experienced more strongly than on road by the cargo ; lack of control of lateral and vertical dynamics of road trailers on rail can cause them to infringe the dynamic loading gauge (ie foul tunnels and bridges), particularly on UK railways.

It is an object of the present invention to provide a bimodal vehicle system in which the above disadvantages are reduced or substantially obviated.

It is a further object of the present invention to provide an improved coupling means for coupling together two vehicles, in particular for coupling together a trailer and a bogie.

The present invention provides a bi-modal system of a vehicle or vehicles intended for use on at least road and rail modes characterised in that it comprises vehicles intended to be moved on the road by means of articulated vehicle tractor units and on rail by specialised rail power units and in that it is designed to operate on rail bidirectionally with substantially equal speed and convenience in either direction of travel in relation to the vehicle's normal direction of travel on the road.

The present invention further provides a coupling means for coupling a bogie and a trailer, characterised in that the coupling means comprises a fifth wheel coupling, which fifth wheel coupling is mounted on the bogie so that it is free to move laterally across the bogie, at right angles to the direction of travel, but is constrained from moving axially along the length of the bogie, in response to rotational movement of the trailer relative to the bogie The movement of the fifth wheel coupling may be restrained mechanically by means of a straight line or parallel motion linkage, for example a Watt linkage.

Embodiments of a bimodal vehicle system and a coupling means will now be described with reference to the accompanying drawings, in which: Figure 1 is a view of a first embodiment of a bimodal vehicle system; Figure 2 is a view of a second embodiment of a bimodal vehicle system ; Figure 3 is a view of a third embodiment of a bimodal vehicle system; Figure 4 is a view of a fourth embodiment of a bimodal vehicle system;

Figure 5 is a view of a fifth embodiment of a bimodal vehicle system; Figure 6 is a view of a sixth embodiment of a bimodal vehicle system; Figure 7 is a view of a rail bogie of Figure 6; and Figure 8 is a view of a coupling system incorporating a fifth wheel bogie.

A first embodiment of a vehicle system for running on rail is shown at Figure 1. It consists of one or more power and driving vehicles A1... An, zero or more load bearing vehicles Bl.... Bn and one or more driving vehicles Cl... Cn. There are typically from zero to seven load bearing vehicles, but there may be more than seven if required. The driver generally occupies the driver's cabin which is at the forward end in the direction of travel, but may alternatively occupy another cabin for short movements in the opposite direction. In either case, the occupied driver's cabin may be in either a type A vehicle or in a type C vehicle.

In an alternative embodiment. as shown in Figure 2, the train consists of one or more power and driving vehicles Al... An, zero or more load bearing vehicles Bl.... Bn and a portable driver's cabin K which can be attached to any of the load-bearing vehicles B 1.. Bn, or to one of the power and driving vehicles Al... An. The portable driver's cabin K is typically attached to the load bearing vehicle at the opposite end of the train from the power and driving vehicle Al. The driver generally occupies the driver's cabin which is at the forward end in the direction of travel, but may alternatively occupy another cabin for short movements in the opposite direction.

In a further alternative embodiment, as shown in Figure 3, the train consists of one or more power and driving vehicles Al... An, zero or more load bearing vehicles B 1.. Bn and one or more further power and driving vehicles L 1... Ln. The driver generally occupies the driver's cabin which is at the forward end of the train in the direction of travel, but may alternatively occupy another cabin for short movements in the opposite direction.

In a further alternative embodiment, as shown in Figure 4, the train consists of one or more driving vehicles Al... An, zero or more load bearing vehicles B 1.. Bn, one or more power vehicles Ml... Mn. zero or more load bearing vehicles Dl.... Dn and one or more driving vehicles E1.. En. The driver generally occupies the driver's cabin which is at the forward end of the train in the direction of travel, but may alternatively occupy another cabin for short movements in the opposite direction.

In a further alternative embodiment, as shown in Figure 5, the train consists of zero or more load bearing vehicles B1.. Bn; one or more power vehicles MI... Mn.; zero or more load bearing vehicles D l.... Dn and one or more portable driver's cabins K which can be attached to any of the load-bearing vehicles or to any of the power vehicles. The driver generally occupies the driver's cabin which is at the forward end of the train in the direction of travel, but may alternatively occupy another cabin for short movements in the opposite direction.

A typical configuration in the rail mode, is shown at Figure 6. In this, the mass of the load bearing vehicles is carried on either a rail type bogie F and/or on part of a power vehicle or on part of a power and driving vehicle. The connections between the load bearing vehicles and the rail bogies and/or the power vehicles or the power and driving vehicles are typically interchangeable and interconnectable with standard road vehicle fifth wheel couplings but not exclusively so.

The rail type bogie F has coupling facilities to enable either the front or the rear of any suitable load-bearing vehicle to be coupled to it. It also has typically primary and secondary suspension systems G, as indicated in Figure 7, to enable load bearing vehicles of differing masses and dynamic characteristics to be carried with low levels of dynamic disturbance to the loads and structures of the load bearing vehicles.

The rail bogie F also has a linkage H which has the function of transmitting any pushing or pulling axial traction forces between the load bearing vehicles towards the axial and lateral centre line of the bogie, to minimise instability of the bogie.

In several of the embodiments, provision is made for one of the rail bogies F to be linked together another bogie and/or a load bearing vehicles and/or a power and driving and/or a power vehicles and/or a driving vehicles, without the presence of a load-bearing vehicle, through a link J, so that spare bogies can be moved by rail to cope with offset traffic patterns or other purposes.

An embodiment of a coupling means is shown in Figure 8, which is a schematic view of a bogie from above.

The bogie shown generally at 10 includes two similar fifth wheel couplings 2,4, one of which will be described in detail. The fifth wheel coupling 2 is provided with a groove (not shown) along the section of its circumference facing towards the end of the bogie 10, which groove is adapted to receive a kingpin 6 of a trailer. The kingpin 6 is adapted to engage the fifth wheel 2 at the centre of the fifth wheel 2 and is free to pivot within the groove about this engagement point.

A Watt linkage shown generally at 20,20'is associated with each of the fifth wheel couplings 2,4 and comprises a first link 8, a second link 12 and a third link 14. The first link 8 and the second link 12 are connected by third link 14, and are mounted on the bogie at their free outer ends on fixed pins at points 16 and 18 respectively. The links 8 and 12 are free to oscillate about points 16 and 18.

The fifth wheel coupling 2 is coupled to a bearing (not shown) on the link 14.

A transverse rigid T-shaped lever 22 comprising a leg 24 and cross-piece 26 is associated with each Watt linkage 20,20'. The free end of the leg 24 is pivotally mounted on the bogie 10, close to the axis of horizontal rotation of the bogie, at 28 and is also pivoted at an intermediate point 30 along its length to the third link 14 of the Watt linkage 20.

Two pins (not shown) provided on the underside of the trailer engage the free ends of the cross-piece 26.

In operation, the mass of each trailer and the axial pulling or pushing forces are carried to the bogie 10 by means of the'fifth wheel'coupling 2,4. This is free to move laterally across the bogie 10 for a short distance, but not axially, being restrained by means of the'Watt Linkage' device 20,20'.

When a trailer is engaged to the fifth wheel coupling 2,4, two pins on its underside also engage with the transverse rigid T-shaped lever 22, as described above, which lever 22 is pivoted to the bogie 10 near to its axis of horizontal rotation and also pivoted intermediately between these points to third link 14 of the Watt linkage 20.

This has the effect that, as the trailer rotates on the fifth wheel 2,4 as the train rounds corners, the longitudinal axis of the trailer is brought nearer to the horizontal axis of rotation of the bogie 10, so reducing lateral forces on the bogie, especially in reverse curves.