IMPROVEMENTS IN OR RELATING TO MEANS OF TRANSPORTATION

This invention relates to means of transportation and concerns guideways and vehicles providing transport for people or things. The guideways may be elevated structures, or may be at ground level or through tunnels. They support the vehicles, guide them and keep them upright.

Vehicle weight may be supported by any known means, such as pneumatic tyres, solid tyres, steel cylindrical or cones wheels, magnetic levitation or air cushion. Guidance may be provided by any known means, for example any of the means last mentioned.

Urban passenger transport mostly uses buses, but these are suffering from road congestion. So called "rapid transit" is generally recognised to be better in principle, but its application is limited by capital cost. Capital cost is related to vehicle size, tunnel size and track specific load. Vehicle size has hitherto been determined by the capacity required. This invention aims to provide transportation means wherein trains may be substantially the same length as at present, but comprise smaller vehicles with better access running more frequently. This may be made possible by enabling people to get on and off quickly and easily.

Conventional rapid transit vehicles place seats along each outer wall. People stand in congested lines between the seats, and in larger areas close to the doors. The situation resembles a rugby scrum at every station during rush hours. People trying to get off have to fight their way out of the vehicle, firstly past those not wanting to alight and then past those already entering the vehicle. This "free-for-all" limits the frequency of trains by delaying them at stations. Delay makes people more determined than ever to get on board, and thus a vicious circle of diminishing returns is forced on everyone. The upshot is that, for all their theoretical capacity, most existing rapid transit systems spend relatively long periods non- productively static at stations, and more especially so at peak periods.

In embodiments according to the invention there may be provided relatively small vehicles, say 3 metres long by 1.5 metres wide, with seats at each end only, wide doors each side and standing room very close indeed to the doors. Each vehicle may carry, for example, twelve to fifteen passengers, of whom up to six may be seated. No passenger is more than approximately 1.3 metres from a door, and preferably passengers leave by one door and enter by a different door on the other side of the vehicle. Trains may comprise, for example, forty vehicles (that corresponds approximately to the length of a London Underground train at present). Passengers can leave freely, without conflict with people standing or entering. Those entering can do so right away, when space is available and have no more than slightly over one metre to move inside the vehicle. This reduces the entering and leaving time at stations, and enables trains to run more frequently.

Such vehicles are required to be tall enough to accommodate standing passengers and narrow enough to keep people close to the doors. This makes them unstable with respect to lateral rolling, especially so because they are preferably light for economic reasons and may run in comparatively long trains. Other problems include traction, load distribution between so many automotive vehicles (i.e. each has a traction motor) and the choice between automatic or driver control. However those problems are no longer insuperable and this invention is to provide means to give transverse stability to very light vehicles, through improvements to guideways and vehicles, and to provide adequate transverse guidance for them to operate in long trains. This is especially important for operation on elevated guideways, where strong winds could cause derailment.

Known forms of transportation system are described in U.S. Patent Specification Nos. 3,083,649 and 3,871,300 and British Patent Specification No. 1,354,888. U.S. Specification No. 3,871,300 and British Specification No. 1,354,888 relate to systems in which vehicles are supported, at the bottom on tracks and are guided by side wheels which engage guide surfaces running parallel to the tracks. The tracks may be provided on elevated guideways. In U.S. Patent Specification No. 3,083,649, on the other hand, there is described an elevated vehicle system in which each vehicle is supported from the guideway in cantilever fashion from one side only. In such cantilever systems problems arise if it is desired to incorporate divergent junctions in the track, where either path out of the junction may be selected, and one object of the present invention is to provide an arrangement which overcomes this problem.

Thus, the present invention relates to a means of transportation of the kind comprising a guideway and at least one vehicle, including an integral load-carrying compartment, traversing said guideway, the vehicle including cantilever support means for engagement with at least one portion of the guideway in such manner that the vehicle is supported in cantilever fashion, outwardly from one side of said one portion of the guideway.

According to the invention, means of transportation of this kind is characterised in that the guideway includes at least one divergent junction and selectively operable switching means are provided to direct the vehicle to follow a selected portion of the guideway out of the junction, and in that the vehicle also includes bottom support means for engagement with at least one other portion of the guideway in such manner that said other portion of the guideway provides upward support for the vehicle adjacent the bottom of the load-carrying compartment and at both sides of the vehicle, a major portion of the guideway providing support for the vehicle by engagement with only one of said support means, and the other support means coming into engagement with the guideway at each said divergent junction to provide temporary support for the vehicle at the junction.

Thus, in a particular embodiment, a major portion of the guideway may provide cantilever support at one side or other of the vehicle, whereas portions of the guideway where the vehicle is provided with bottom support at both sides are used at junctions in the guideway where the vehicle requires to be directed to follow a selected path out of the junction. The provision of temporary bottom support for the vehicle at such junctions allows the means providing cantilever support at one side of the vehicle to be disengaged as the vehicle traverses the junction and reengaged, perhaps on the other side of the vehicle, with the new portion of the guideway which the vehicle is to follow.

The following is a detailed description of embodiments of the invention, reference being made to the accompanying diagrammatic drawings in which:

• Figure 1 is a vertical section through a guideway and a vehicle,
• Figure 2 is a schematic plan of a junction in a track for the vehicle shown in Figure 1,
• Figure 3 is a longitudinal section through a vehicle, showing one rail beam,
• Figure 4 is a plan view of a vehicle, showing the arrangement of the support and guide wheels, doors and seating,
• Figure 5 is a section on the line A-A of Figure 2 with the vehicle switching left,
• Figure 6 is a section on the line B-B of Figure 2,
• Figure 7 is a section on the line A-A of Figure 2, with the vehicle switching right. It also shows means for the vehicle to operate on a different sort of guideway when the vehicle travels cantilevered from the side of a guideway wholely to its right,
• Figure 8 is a diagram in a vertical plane, showing the forces acting upon the vehicle shown in Figure 5,
• Figure 9 is a vertical section showing a modified form of vehicle cantilevered from the left,
• Figure 10 is a vertical section showing a vehicle cantilevered from the right,
• Figure 11 is a plan view of a section of guideway following a divergent junction,
• Figure 12 is a plan view of a divergent junction for on-board switching leading into two cantilevered tracks,
• Figure 13 is a plan view showing a vehicle similar to that in Figures 1 to 8, but modified for on-board switching,
• Figure 14 is a part vertical section of a vehicle showing an alternative construction which functionally resembles that shown in Figure 13.
• Figure 15 is a part vertical section through the upper portion of a vehicle and guide surfaces which are provided according to another feature of this invention,
• Figure 16 is a plan view of a divergent junction for the arrangement of Figure 15,
• Figure 17 is a plan view near the line 110 of Figure 16, showing a vehicle on the guideway,
• Figure 18 is a plan view near the line 111 of Figure 16, showing a vehicle on the guideway,
• Figure 19 is a plan view near the line 112 of Figure 16, showing a vehicle on the guideway,
• Figure 20 is a plan view near the line 113 of Figure 16, showing a vehicle on the guideway,
• Figure 21 is a plan view near the line 114 of Figure 16, showing a vehicle on the guideway,
• Figure 22 is a vertical section through a cantilevered vehicle according to another feature of this invention, which vehicle may optionally be provided with on-board switching,
• Figure 23 is a side elevation of the vehicle and track shown in Figure 22,
• Figure 24 is a vertical section through a station, with two vehicles stopped there, being on journeys in opposite directions,
• Figure 25 is a side elevation of the station shown in Figure 24 also showing guideways leading thereto,
• Figure 26 is a vertical section through a guideway according to another feature of this invention,
• Figure 27 is a plan of the guideway shown in Figure 26, the lower rail and some sleepers being omitted,
• Figure 28 is a side elevation of the guideway shown in Figures 26 and 27,
• Figure 29 is a vertical section through a modified guideway structure,
• Figure 30 is a vertical section through another form of guideway structure, where four pin-jointed plane structures comprise a torque tube,
• Figure 31 is a plan view of the structure shown in Figure 30, the sleepers and lower rails being omitted,
• Figure 32 is a side elevation of the main structural part of the guideway structure of Figure 30,
• Figure 33 is a plan view of a curved section of track for the guideway structure of Figure 30, showing the offsetting of rails.
• Figure 34 is a vertical section through cylindrical steel wheels which may be used in arrangements according to the invention, one of which wheels optionally may be flanged,
• Figure 35 is a plan view of two vehicles coupled together traversing a curved section of track, and
• Figures 36 and 37 are similar views to Figures 17 to 21 showing alternative forms of guide wheels.

Figures 1 and 3 show a vehicle and guideway whereby the vehicle is transversely located and stabilised according to this invention. As best seen in Figure 1, the vehicle 1 is supported by two pairs of wheels, each pair being mounted on a solid axle. Wheels 2 and 3 are mounted on an axle 12 and there is another similar pair at the other end of the vehicle on an axle 38 (see Figure 3). Surface strips 4 and 5 provide running surfaces on I-beam longitudinal rail members 6 and 7. The support wheels 2 and 3 are pneumatically tyred and are provided with safety discs 8 and 9. These are engageable with check rails 10 and 11 to prevent derailment at junctions. The check rails may be jointed to the I-beams (as shown) or to the running surfaces. Normal lateral guidance is provided by horizontal guide wheels 16, 17 mounted in pairs, each pair being substantially in the same vertical plane as the axle of one pair of support wheels. The guide wheels 16, 17 are also pneumatically tyred. The pneumatic tyres on the support and guide wheels each allow sufficient lateral drift for the vehicle to be steered by the guide wheels without the necessity of means for angling the support wheels, this being made possible by the short wheelbase of the vehicle. Safety discs 14 and 15 are fitted above the guide wheels 16 and 17 respectively. The guide wheels 16, 17 and safety discs 14, 15 are freely mounted on vertical shafts 20, 21, which shafts may be rigidly mounted on the vehicle. The safety discs may be attached to the guide wheels or may be separately mounted.

Part of each safety disc 14, 15 underlies the upper horizontal flange of the associated I-beam and prevents vertical displacement of the vehicle from the I-beams, thus preventing derailment or overturning of the vehicle.

Power distribution rails 22 and 23 may be mounted beneath the guide wheels and engaged by collectors 24 and 25. Similarly, signal rails 26 and 27 may communicate with vehicle mounted receivers 28 and 29. If desired, linear motors 30 and 31 may also be situated beneath the support surfaces of the I-beams, and between their webs, to engage conductor strips 32 and 33 and obtain their tractive effort therefrom.

As shown in Figure 3, a lower portion 34 of the vehicle extends beneath the support surfaces and between the I-beams. The floor of the vehicle upon which passengers stand is indicated at 35 and seats 36 and 37 cover the axles 12 and 38. A traction motor 39 drives shaft 38 through a toothed belt 40.

Figure 1 also shows protective angle-section beams 41 and 42, which are so situated that they take the wear of the guide wheels 16, 17 rather than allowing the wheels to wear the surfaces of the main structural I-beams. The horizontal surfaces of the beams 41, 42 are engageable by the safety discs 14, 15 fitted to the guide wheels.

Figure 4 shows also horizontal guide wheels 43 and 44 at the opposite end of the vehicle, and sliding doors 45, 46, 47 and 48.

It will be seen that the guideway and vehicle system which has been described provides admirable transverse location, stability against rolling, a neat, economical and attractive guideway structure, protection for conductors and signal rails and a clear floor space for the passenger compartment of the vehicle, together with low cost mechanical construction, and excellent access and egress. Special provisions are required for switching the vehicles at junctions and such provisions will now be described.

Referring to Figures 1 and 4, a solid tyred idler wheel 49 is mounted in the centre of the specially strengthened roof of the vehicle. The wheel 49 is freely rotatable on its shaft, the axis of which is vertical.

Referring to Figure 2, the pitch lines of the rails 6 and 7 diverge as they extend past the apex of a junction. A vehicle passing the junction is kept upright and guided by engagement of the wheel 49 with either of two switch surfaces 50 or 52 on a switch member 51 pivotally mounted over the guideway so as to lie above the roof of the vehicle, as shown in Figure 1. When the switch member 51 is engaged by the wheel 49, there is a slight lead-in ramp (not shown) and the vehicle is thereby fractionally tilted, for example, towards the right. To facilitate this inclination, the top portion of the angle beam 41 is thinner than that of the angle beam 42. This allows the wheels 16 and 43 to lift fractionally. At approximately the same location on the guideway, the check rails 10 and 11 on the inner edges of the I-beams are discontinued. The vehicle is then held to one side by the reaction exerted by the switch member 51 on the wheel 49. This guides each vehicle past the junction until it is supported on both sides again.

A fixed guide surface 53, which forms a temporary fixed continuation of the switch member 51 along the right hand guideway, is discontinued shortly after the junction, at position 54. When in the position shown in Figure 2, the switch member 51 is supported by its vertical pivot shaft 55 and by a stop 56. Alternatively, the switch member 51 may be pivoted to the position represented by the broken line at 57 in Figure 2, so that vehicles are then routed to the left at the junction and a stop 62 supports the switch member. Figure 5 also shows the switch member 51 in the position indicated by the broken line 57 of Figure 2. It will be noted that the vehicle is kept upright by the upper guidewheel 49 engaging the switch member 51, and that it is cantilevered from the left.

After the position indicated at 59 in Figure 2, an I-beam rail is again provided on both sides of each guideway beyond the junction. The said further I-beams are indicated at 60 and 61 respectively.

Referring to Figure 6, a vehicle such as that shown in Figure 1 is provided with bottom support on both sides, by four wheels. The rail I-beams 6 and 7 are supported on a trellis structure comprising spaced uprights 67 joined by a transverse tie member 68. Such members 67, 68 form arches supporting the longitudinal rail members, which span the distance between the arches.

Figure 7 shows the vehicle cantilevered from the right. It will be noted that it is supported by two of the same support wheels as in Figure 6, but on one side only, and that it is kept upright by engagement of the wheel 49 with the switch member 51.

A vehicle which is cantilevered from the left or from the right, as in Figure 5 and 7, to pass' through the junction, may continue to be supported in that manner beyond the junction. The switch member 51 may then be replaced by a fixed rail or guide, designated 70 in Figure 7 (represented by the same component as the switch member 51). The rail 70 may be supported by structural members such as a transverse beam 71 and a column 69. The column 69 may also support the rail beam, such as 7 or 6.

Referring to Figure 8, the weight 71 of a vehicle, cantilevered from the left, acts downwards through the centre of gravity 72 and this force is balanced by the upward supporting force 73, with moment arm 74. The forces are equal, and produce a resultant couple equal to either 72 or 73 acting at distance 74. This couple is balanced by that of the guide forces. The top of the vehicle is held in, thereby keeping it upright, by force 75 acting (for example) on the wheel 49. This is balanced by the forces on the lower guide wheels 16 and 43 (see Figure 4), acting outwards with a force which will be equal and opposite to 75 (in the absence of disturbing loads, such as transverse winds and/or centrifugal force). Each said horizontal force acts on a moment arm 77 producing a couple acting in the opposite direction to that produced by the weight and vertical reaction. Since 75 automatically adjusts to the applied load, these two couples automatically balance. Wind and centrifugal loads are carried by additions to or subtractions from loads 75 and 76, so that their algebraic sum is unchanged - i.e. a force of one Newton acting from left to right through the centre automatically causes one half that force to be added to the load 76 and one half to be subtracted from 75. Couples produced by wind will be automatically compensated by changes in the value of both loads 75 and 76.

The guide member, such as 70 in Figure 7, requires an overhead supporting structure, and this may be eliminated if side followers are provided, as in Figures 9 and 10. Figure 11 represents a section of guideway, for movement of vehicles from bottom to top. Initially, the vehicles are supported on the rail 6 and kept upright by the upper guide rail 70. Subsequently, an additional side guide rail 78 is provided. This is engaged by anotherfollower 79 (see Figure 9) and the upper guide is discontinued after a short overlap. As shown in Figure 9, the side follower member 79 may comprise a wheel 80 idling on a shaft carried by an arm 81. The guide 78 may comprise a rail attached to spaced columns such as 82, which also carry the support rail 6. The side follower may be duplicated at the front and back of the vehicle respectively, and it is only necessary at one side, if it is desired to cantilever the vehicle from one side. However, it is desired to be able to cantilever the vehicle from either side, then another (optionally duplicated) side follower, such as 83, may be provided. Figure 10 shows how the vehicle may be cantilevered from the right, being guided and kept upright by the follower 83, engaging a rail 84 which is supported by a column 85 which supports the right hand track rail.7.

On-board switching may replace on-guideway switching as described above. For example, the side followers 79 and 83 may be pivotably mounted about fore and aft axes 86 and 87, and articulated by on-board means, under computer control, so that either follower arm may take up the inclined position represented by the broken lines in Figures 9 and 10 and by broken axis lines 86-88 and 86-89, also by broken lines 87-90 and 87-91.

When such pivoting means are provided, the rails 78 and 84 may continue through the junction, as shown in Figure 12. The side guide rails 78 and 84 are provided before and through the junction, and vehicles reach the junction, travelling from the bottom to the top of the drawing, with bottom support from the track rails 6 and 7. Substantially before the junction, every vehicle selects either the guide 78 or the guide 84, and immediately before the junction each of these guides is biased slightly away from the centre of the guideway, so that a vehicle engaged with the guide 78 is tilted out of supporting engagement with the track 7, and is in fact cantilevered from the left before the tracks 6 and 7 diverge at the junction. Similarly, vehicles engaged with guide 84 are slightly tilted to the right, immediately before the junction is reached, so that they become supported only from the track beam 7. In each case, vehicles follow the tracks 6 or 7 respectively through the junction, and may continue cantilevered from the left or the right respectively. Optionally bottom support on both sides may follow the junction, as represented in Figure 12 by the renewal of rails 6 and 7, and also the guides 78 and 84. Optionally the pivot axes of the followers on both sides may be coincidental and they may thus form one rocker member.

In Figure 13, the vehicle 93 moves from the bottom to the top of the drawing. An upper guide wheel 125 is mounted on a crankshaft, comprising a shaft 98 and a web 97, which is movable by on-board means, whereby the guide wheel is movable between positions 92 and 94. Stops 95 and 96 limit the movement of the crankshaft. The crankshaft is moved before the vehicle 93 reaches a junction, and the guide wheel then engages one or other of upper guide member 99 or 100, which guide the vehicle to the appropriate side of the junction, and keep it upright.

In the arrangement of Figure 14, upper guide wheels 101 and 102 are mounted on a rocker arm 103, which is pivotable on a shaft 104 and operated by on-board means, so that the wheels 101 and 102 may be moved to positions 105 and 106 respectively. Upper guide members 108 and 109 are stationary and correspond to the guide members 99 and 100 of Figure 13, so that when the wheel 101 engages the guide 108 the vehicle 107 is guided to the left at a divergent junction which follows, and when the wheel 102 engages the guide 109, it is guided to the right. In both cases the vehicle is kept upright by the wheel at the time in engagement with its appropriate guide.

In the above arrangements with on-board switching the length of guideway where bottom support is provided in advance of the junction requires to be sufficient to allow for verification of the setting of the switching means together with a safe emergency stop length. Figures 15 to 21 show an alternative arrangement whereby the switching means may be pre-set, and its setting verified, while the vehicle still remains cantilevered from one side only. Instead of the length of bottom support required by the previous arrangements, this arrangement needs only a sufficient length of bottom support to ensure continuity of guidance at the junction, with overlap between the bottom support and cantilever support of up to one vehicle's length. This advantage is achieved by providing, in addition to the articulated upper guide wheel 125 of Figure 13, further upper guide wheels which rotate about fixed vertical axes, i.e. are unchanging. These unchanging guide wheels provide part of the cantilever support of the vehicle during normal operation (i.e. other than when actually passing junctions), and enhance safety.

This embodiment is made possible by small guide wheels which have been found to be commercially available, to meet the load and speed requirements. For example, for a 16 passenger vehicle, the guide wheels may be 15 ins (38 cms) or 16 ins (40.5 cms) diameter. The 16 ins diameter would be suitable for the fixed axis wheels for continuous use. The 15 inch diameter would be suitable for the articulated wheel.

Figure 15 shows a vertical section (looking from the rear) through the upper portion of a vehicle 115, provided with four fixed axis guide wheels 116 to 119, and Figure 16 is a diagrammatic plan view of the vehicle. The four guide wheels idle on shafts mounted on the upper portion of the vehicle and have vertical axes.

On approaching a junction, Figure 16, a vehicle at position 110 is cantilevered from the left, with bottom support on that side only, the axis of the left hand bottom support rail being indicated at 130. The vehicle is guided and kept upright by engagement of the upper guide wheels 116 and 119 with a left hand upper guide surface 131, as shown in Figure 17. The guide surface 131 is provided on one side of an inverted channel track member 121 which embraces the upper guide wheels 16 and 19, whereby any reversal of transverse load, such as might be caused by wind, centrifugal force, or accident conditions, is carried by the opposite guide surface 120 of said member 121. A similar inverted channel track member 123, for engagement by the wheels 117 and 118, is also shown in Figure 15. However, it will be understood that both members 121 and 123 would be provided at a junction for an overlap change-over from cantilever from one side to cantilever from the other, but not normally at the same place under any other conditions. The members 121 and 123 are supported on a transverse upper beam 124.

The vehicle is provided with means allowing bottom support from either side or from both sides simultaneously, as has been described. Near-central upper guide surfaces 127 and 128 are provided for the articulated wheel 125, which is movable to an alternative position 129, as shown in broken lines in Figure 15. The operation may be as follows. Vehicle movement is from left to right of Figure 16.

As the vehicle, cantilevered from the left, approaches the divergent junction, the crankshaft 126 is free to move, and during the approach period, as soon as possible after leaving the last junction, it is moved to the position required for the oncoming one. This movement is verified and an automatic stop procedure is effected should correct operation fail to be verified. Figure 17 shows the position of the crankshaft 126 and wheel 125 for selecting the right hand path out of the junction. This corresponds to the position 129 of the wheel, as shown in broken lines in Figure 15.

On reaching position 111, the central upper guide surfaces 127 and 128 are provided. The right hand surface 127 is engaged by the wheel 125, loading the crankshaft against the stop 96, and very slightly tilting the vehicle to the right, so that there is no shock when its left hand bottom support wheels leave their rail. This position is shown in Figure 18. At this stage the vehicle is bottom supported from both sides, with load being transferred from left to right. The right hand bottom support rail is indicated at 130a. Shortly afterwards, the guide surface 131 is discontinued, so that, whichever side has been selected by the guide wheel 125, the vehicle can follow it.

Figure 19 shows the condition at position 112 of Figure 16. It will be noted that the guide surface 131 has been discontinued, and top guidance is effected solely by the guide surface 127 acting on the wheel 125. If the vehicle had been switched left, the wheel 125 would have followed the left hand guide surface 128 until the resumption of the guide surface 131 again took over the upper support of the vehicle.

Figure 20 shows the vehicle near positon 113 of Figure 16. The upper guide surface 133 of the right hand track member 123 has been engaged by the upper fixed axis guide wheels 117 and 118. The guide surface 127 is subsequently discontinued and the vehicle remains under the guidance of the wheels 117 and 118, acting on the surface 133.

Thus, as the vehicle passes through the junction, its support is as follows. In Figure 17 (position 110) the vehicle is cantilevered from the left. In Figure 18 (position 111) bottom support is provided on both sides, while load transfer is taking place. In Figures 19 (position 112), 20 (position 113) and 21 (position 114) the vehicle is cantilevered from the right.

A corresponding sequence is followed by vehicles branching left, and at convergent junctions. Vehicles may change from cantilever left to cantilever right, and vice versa with bottom support at both sides for no longer than is required for shock-free load transfer.

At convergent junctions, fixed guide blades may engage the crankshaft mounted guide wheel 125, to move it, if necessary, to ensure that it is correctly positioned.

In the arrangement of Figures 22 and 23, the vehicle 134 is carried by two support wheels 135 and 136, being cantilevered outwards therefrom and kept upright by upper guide wheels 137 and 138. The reaction from those wheels is balanced by two lower guide wheels 139 and 140. The support wheels run upon surface members (not shown) over rail and structural member 141. This is an I-beam, web vertical, the upper flange of which supports the wheels. The vertical flange of an angle section check rail 142 prevents derailment by engaging a safety disc 143 which is coaxial with the wheel and rotates with it.

The lower guide wheels 139 and 140 idle about vertical axes, running against the web of the I-beam. They are provided with safety discs 144 and 145. These are engageable with the underside of the top flange 146 to prevent the support wheels from lifting over the check rail 142.

The upper guide wheels 137 and 138 idle on vertical shafts rigidly joined to reinforcements in the roof of the vehicle. They run on the web of the I-beam 147. They are provided with safety discs 149 and 150 which are engageable with the lower flange of the I-beam 147, to prevent derailment. Reverse loading upon the upper or lower guide wheels may be created by transverse strong winds and/or collision conditions on curves. On the upper guide wheels, such loads are carried by the engagement of the other sides of the wheels 137 and 138 with a second upper track member 148. On the lower guide wheels, the loads are carried by the engagement of the safety discs on the support wheels with the check rail.

Figure 22 shows, in broken lines, a sliding door 151 on the vehicle 134 and a precisely located door 152 in the wall facing it. A station may be provided to the right of the wall, at 153. Thus access to the vehicles is between the upper and lower rails.

Figure 24 shows a double-sided station. Vehicles 154 and 155 ride on tracks 156 and 157. Lower guide wheels 158 and 159 run over the outer surface of the track members. The upper guide wheels 160 and 161 are horizontal, just above the roof of each vehicle, and attached thereto, so that their outer edges are substantially on the same plane as the vertical inner wall of the vehicle. Their inner edges engage vertical track surface members 162 and 163, which overhang the tops of the vehicles and are secured to transverse beams 164, 165. Doors 166 and 167 align with stationary doors 168 and 169. The station platform 170 is supported on columns 171 and 172.

Figure 25 shows three sets of sliding doors, 173, 174 and 175, in the vertical wall of the station 176, which is supported on columns 177 and 178. The upper guide rail (corresponding to member 147 of Figure 22) is indicated at 179, and the lower guide and support rail (corresponding to member 141 of Figure 22) is indicated at 180. These members are continuously parallel throughout the approach to the station, the station itself and the following section of track structure. Spans 181, 182 and 183 connect with the station. Each comprises upper and lower rail members 179 and 180, with vertical struts and diagonal cross bracing. The vertical struts are more closely spaced at the end of each span than in the centre, for reasons of appearance, and the spans are supported on columns such as 184, 177 and 178.

In Figures 22 and 23 a traction motor 185 is mounted beneath the floor of the passenger cabin 1185, and lower than the point of contact of the support rail with the support wheels. The axis of the output shaft of the motor is parallel to the axes of the support wheels and drives one of the support wheels by means of a belt. This leaves the floor space clear, and is conveniently situated for power collectors, which may also be situated beneath the floor as indicated at 186 in Figure 22.

The station and sections of track shown in Figure 25 may be double-sided, as in the station in Figure 24, so that traffic in the far side travels in the opposite direction to that on the near side. A walkway may be provided between the two tracks as represented by handrail 2185. There may be provided special guideway structures as follows.

Referring to Figure 26, T-shaped rails 186 and 187 carry the weight of the vehicles passing respectively on either side of the structure, and their vertical surfaces provide guide surfaces for the lower horizontal guide wheels, generally as has been described. The rails are supported by transverse sleepers such as 188, which themselves may conveniently be joined by horizontal longitudinal structural members, such as 202. Where appropriately situated, each sleeper may directly rest upon a step in the vertical support column, such as 189. These columns are also connected by upper guide rails 190 and 191, which may be joined thereto by transverse sleepers such as 192.

In the arrangement of Figure 27, columns 189 and 193 pass through the lower composite beam (to be described) and locate an upper composite beam through sleepers such as 192 and upper guide rails 190 and 191. The columns are effectively rigidly joined to said upper horizontal composite lattice braced flat beam, comprising said sleepers, said upper guide rails, main longitudinal structural member 194, which may conveniently be situated on the centre line, and diagonal bracing members such as 195, 196 and 197. Thus the horizontal loads imposed by cantilevered vehicles upon the upper guide rails 190 and 191 are carried by said composite beam and transmitted thereby to the tops of the columns 189 and 193.

The horizontal loads imposed by the lower guide wheels upon the vertical sides of the rails 186 and 187 are carried by similar lattice braced flat horizontal beams comprising said rails, main horizontal lower structural member 202 and suitable lattice bracing such as diagonal members corresponding to those shown in Figure 27.

The vertical loads imposed by the weights of vehicles upon the rails 186 and 187 are carried by a centrally disposed composite lattice braced beam comprising the two aforesaid longitudinal structural members, 194 and 202, suitable spaced vertical beams such as 1960, and diagonal cross bracing members such as 1970.

It will be appreciated that the columns must extend to the top of the structure in order to locate the upper flat beam transversely, and that the rails must therefore pass to either side of them, being offset from the centre line generally as shown in Figure 26 and Figure 28. Thus the weight of vehicles produces a couple which is carried as a bending moment in the lower transverse sleepers. These are bracketed (i.e. provided with joints capable of transmitting the said couple) to vertical beams, such as 1960 and through them to the upper composite flat horizontal beam, as generally shown in Figures 26 and 27. This couple thereby produces a pair of equal and opposite transverse forces, in said upper and lower composite horizontal beams respectively. Said couples may be transmitted longitudinally by the two composite horizontal beams to the vertical columns and ultimately thereby to the ground.

Figure 29 shows an alternative embodiment of the invention whereby the vertical composite beam (generally as shown in Figure 28) is duplicated. In this case the side elevation generally resembles Figure 28 and the two vertical composite beams are as represented by 198 and 199 in Figure 29. The vertical members corresponding to member 1960 remain beams carrying the couple produced by the sleepers. Said couple may either be transmitted by said vertical beams both sides, whereby both help to carry the weight, or alternatively, if only one side is carrying a vehicle or vehicles, the vertical composite beam one side may carry the load, acting upwardly, and the other vertical beam may act downwardly upon the other ends of the sleepers (i.e. the ends opposite to the ends carrying the load of the vehicle or vehicles) in order to carry the said couple due to the rail being cantilevered beyond the upwardly acting beam.

If desired for maintenance purposes, and/or for any other purposes such as an emergency escape route for passengers from any broken down vehicle or vehicles, a pedestrian walkway may be provided between the vertical beams 198 and 199. This may have balustrades, such as 200 and a deck 201 may be fitted between the two vertical composite beams.

According to another embodiment of this invention, shown in Figures 30 to 33, there may be provided a track structure carrying vehicles as aforesaid, whose spans are rectangular torque tubes formed from four pin-jointed plane-structures, which torque tubes are secured to the plane top surfaces of columns.

With reference to Figures 30 to 33, it must be explained that the term "pin jointed" is derived from analytical considerations, whereby structures of the type considered may be stressed in a manner resembling those which would exist if pin joints, or more truly, ball and socket joints, were fitted at the ends of each strut or stay. Moreover, main longitudinals may be considered to be fitted with ball and socket joints (for purposes of stress consideration) wherever they are joined by transverse members and/or diagonals.

In this sense "pin-jointed" means that the structural members are subject principally to forces acting in compression or in tension along their axes. A "torque tube" means a structure comprising a tube, whose walls may be composite pin-jointed structures, and which is designed to transmit torque.

Columns 203 and 204 carry discrete guideway members such as 205. Each said beam comprises four main longitudinal structural bars, such as 206, 207, 208 and 209. These may, for example, comprise structural steel joists, tubes or extruded light alloy tubes. Their axes lie virtually at the corners of a-rectangle, as shown in Figure 30. All four are connected at intervals, in spaced transverse planes, by four transverse members, such as 210, 211, 212, and 213 and by a diagonal stay member (which may also serve in compression) such as 214. These transverse frames are joined by diagonals each side, such as 215, and by diagonals top and bottom such as 216. Rails, as described above, may be attached by sleepers top and bottom, which sleepers are secured to attachment points such as 217 and 218.

In order to provide visual coherence to the structure as a whole, and also to eliminate the unsightliness of track members against the sky, a roof such as 219 may be fitted. In addition, a pedestrian walkway may be fitted within the structure, with balustrades such as 200 and a deck such as 212. It is noteworthy that there is enough room under the diagonal member 214 for people conveniently to walk along the walkway.

Figure 33 shows how this structure is adaptable for curves. Spans of straight guideway structures 220, 221 and 222, lie along chord lines, with mitred ends. Curved rails such as 223 and 224 are secured thereto by offset sleepers such as 225, to the mounting points provided at the transverse frames of the beams, such as 226 and 227.

It will be noted that the four longitudinal structural bars, together with cross frames and diagonals such as 216, which lie in the planes of the sides of the rectangle at whose corners the main longitudinals lie, form a torque tube. The cantilevered sleepers carry a couple from the rails and this is applied to the central portion of the said torque tube, when loaded there, at one side. It is carried by the torque tube to its ends, and there transmitted to the top of the columns, through anchorage points such as 1228, to the columns such as 203. This torque would tend to distort the torque tube into a lozenge or parallelogram shaped cross-section, but such distortion is prevented by diagonals such as the member 214.

In connection with the guideway shown in Figures 30 to 32, it will be noted that the upper lattice braced beam effectively transmits the outwardly acting load from a vehicle longitudinally to the vicinity above the support columns.

In connection with Figures 26 to 32, the terms horizontal beam and vertical beam refer to the major axes of their cross-sections. It will be seen that the provision of the horizontal beam at the top of the guideway structure reduces the tendency for the top to be twisted sideways at the centre of a span.

A vehicle as described herein may be provided with bottom support through four cylindrical steel wheels and four cylindrical guide wheels as shown in Figure 34. The steel rail 228 supports a cylindrical wheel 229, which is located by and rotates with a long axle whose axis of rotation is indicated at 230 0 231. This axle may carry support wheels such as 229 at both sides of the vehicle, as in conventional railway practice. However, in order to carry the relatively high transverse loads which may be associated with cantilevered operation as herein described, instead of using conventional flanged wheels, lateral guidance is provided by separate cylindrical steel guide wheels, such as 232, which are mounted upon a long, well supported axle whose vertical axis of rotation is indicated at 233-234. It is preferable that the surface of this wheel is parallel to the side surface of the rail 228 upon which it bears. It is not necessary that the axes 230-231 and 233-234 should lie in the same plane, but this may be preferable in order to keep the support wheels in the centres of the rails on curves. Wheels 229 and 232 may abut in the region of 235, where the relative motion will be small or zero. Advantages of this embodiment are that steel wheels are very much smaller and wear less than pneumatic tyres and in particular it may be preferable to use steel wheels for guidance purposes. This embodiment is especially suitable for switching as described herein, whereby the cantilever support is used for switching of bottom supported vehicles, because the cylindrical guide wheels are preferable to flanged wheels, and this method of switching eliminates the reduced clearances through which flanges have to pass on conventional railway switches.

Figure 35 shows the general instance of a train of bottom-supported vehicles which may be provided according to this invention. Two vehicles 236 and 237 are each supported upon two pairs of wheels, such as 238 and 239, which are mounted in pairs upon solid axles such as 240 - i.e. the wheels do not rotate on the shaft, the shaft rotates and is axially located in bearings. Rectangular plinths, 243, 244, or I-beams are provided for these support wheels to run upon, and for guidance. Each said vehicle is guided by four horizontal wheels, such as 241, whose axes of rotation may intersect those of the nearest support wheels. Two adjacent such vehicles are coupled with an axis of pivoting indicated at 242.

Guide wheels such as 232 (Figure 34) may optionally be provided with flanges, such as 245, which may engage the underside of the rail head, positively to preclude derailment. It is noteworthy that switching as described herein by canti- levering the vehicles remains possible, because the wheels on the opposite side may draw clear (e.g. by a slight increase in gauge) as the cantilever support is caused to become operative.

In the form shown in Figure 35, damping may be provided in connection with the pivoting of adjacent vehicles relative to one another, about a vertical axis. Such damping may be applied to the coupling at 242, or alternatively it may be applied through buffers, such as 245 and 246, which are offset from the centre line. Such damping is to ensure stability against transverse oscillations about vertical axes, especially at high speeds.

Figures 36 and 37 show a modified version of the arrangement described with reference to Figures 17 to 21, in which there is provided a pilot wheel coaxial with each guide wheel, whereby said vehicle is steadied before the engagement of the guide wheel with the fixed guide surface, and the guide wheel is also spun up before engagement.

Figure 36 shows fixed axis guide wheels 250 to 253, provided with respective pilot wheels 246 to 249 coaxial therewith. As the vehicle 254 moves from left to right, it is steadied, before the guide wheel 251 engages the fixed guide 256, by the engagement of the pilot wheel 247 with a pilot surface 255, which is provided with lead in. The engagement of the pilot wheel with the pilot surface also imparts angular acceleration to the guide wheel 251, whereby its shock on engagement with the guide 256 is reduced.

Figure 37 shows a pilot wheel 257 coaxial with the crankshaft mounted guide wheel 259, which pilot wheel is engageable with a pilot surface 258, which is provided with a lead in, as shown. This steadies the vehicle, ensuring correctly located engagement of the guide wheel 259 with the guide surface 260, while the guide wheel 259 is given some degree of angular acceleration prior to engagement, whereby wear and shock are reduced.

It is noted that the pilot wheels may be above the level of the guide wheels, and, being smaller, there is enough room for adequate lead in. There may not be enough room for adequate lead in on the guide surface of the larger wheels.

In this specification, the term "bottom support" means support applied to the vehicle beneath the level of the floor of the cabin, or load carrying compartment, and not necessarily below the lowest extremity of the vehicle.

When not otherwise specified or made cfear, the term "guideway" means the rails and the structure and/or foundations supporting them. The term "rail" means the member over which the wheels or their equivalent run. It may optionally be protected by a surface member. "Specific load" means the load per unit length (e.g. Newtons per metre). "Coned wheels" includes wheels which are both coned and flanged. "Capacity" means the passengers carrying capacity, for example in passengers per hour in one direction.

"Support" signifies weight carrying, acting vertically. "Guidance" signifies horizontal forces to constrain the vehicle to follow the track and to remain correctly orientated transversely.

"Sleepers" signify transverse beams connecting the rails to the main structure of the guideway. "A plane structure" signifies one whose general shape resembles a plane or strip - e.g. the flange of an I-beam, whether comprising a solid strip of metal, or a flat composite lattice braced structure or any such form. A "beam" is a structural member designed to carry a couple acting about an axis perpendicular to its length. A "railhead" is a bulk of metal whereby Hertzian stresses are distributed in depth, as in 228 of Figure 34.

"I-beam" means any body or structure the cross-sectional shape of which resembles the capital letter "I", for example comprising two plane horizontal strips or flanges joined together by a vertical web, and includes hollow and frame structures as well as solid beams.