To be able to be used both as a cycle and as a trolley on rails, rail cycles of this type have the support arm that carries the extra support wheel attached to the rail cycle's frame by an articulated joint so that this can be raised up from its folded-down, in-use position to a non- working position against the rail cycle's frame and accordingly not be in the way when the rail cycle is to be used as a conventional cycle. Similarly, the guiding device whose function is to the keep the cycle's front and rear wheels on one of the rails of the railway track should be able to be set aside or in some other way be arranged in a non-working position so that the rail cycle can be used as a conventional cycle for conveyance on a road.

From US 0 695 826, a rail cycle with a guiding device for the front and rear wheels like that mentioned above is known. This has guide rollers in front of the front wheel and behind the rear wheel that rotate and are supported by rods that can be swung out from their attached positions to the rail cycle's frame. The rollers that are supported by the rods can be manoeuvred between a non-working and a working position by swinging them into raised and lowered positions respectively. This can also be compared with US 4 230 046 and US 1 436 532.

One common factor for the known techniques described above is that the guiding device, when in its working position, does not have its effect directly alongside the front and the rear wheels, whereby a satisfactory guiding of the front and the rear wheels on one of the rails is not achieved when the rail cycle is used for conveyance along a railway track.

However, a rail cycle of the type referred to in the introduction and that has a guiding device that has its effect alongside the front and the rear wheels is known from SE 014 177. This guiding device includes flanges positioned on either side of the said rail and that extend radially beyond the outer circumference of the wheel. However, this rail cycle according to the said document cannot be used as a conventional cycle as the guiding device cannot be arranged so that it can be set aside or placed in a non-working position should the rail cycle be considered for use as a conventional cycle.

The present invention has the object of achieving an improved rail cycle of the type referred to in the introduction. In more specific terms, it seeks to achieve a rail cycle with a guiding device that provides fully satisfactory guiding of the cycle's front and rear wheel on one of the rails when it is used as a rail trolley, and that can also be arranged in a non-working position in those cases when the rail cycle is used as a conventional cycle.

This objective of the present invention is accomplished by means of a rail cycle with the characteristics given in the claims that follow.

The drawings show; fig. 1 is a rear view of one embodiment of the rail cycle according to the present invention; fig. 2 is a view from above the rail cycle according to fig. 1 ; fig. 3 is a side view of the rail cycle according to fig. 1 from the side without the extra support wheel; fig. 4 is a partly cut-away view of one of the cycle's wheels provided with a guide according to the invention.

The foldable rail cycle shown in figs. 1-3 is given the general designation 10. The said rail cycle 10 includes a frame 12, to which a rotating front wheel 14 and a rear wheel 16 are mounted. When the rail cycle 10 is to be used as such, the front and rear wheels, 14 and 16 respectively, are in contact with one of the rails 17 of the railway track. The front and rear wheel, 14 and 16, will be described in more detail below with reference to fig. 4.

The rail cycle has, in the traditional manner, a saddle 18 mounted on the frame, plus handlebars 20, also mounted on the frame. The rail cycle's 10 rear wheel 16 is driven by a transmission device in the form of a loop chain, that functions together with a smaller cogwheel 24 on the rear wheel 16 and a rotating larger cogwheel 26 mounted on the frame 12 that carries pedals 28 that are permanently attached to the larger cogwheel 26.

As is best evident from figs. 1 and 2, the rail cycle 10 according to the invention has a supporting arm 30 that supports a rotating extra wheel 32 at its end furthest from the frame 12 of the rail cycle 10, and that, when in use, is in contact with the other rail 34 of the railway track. When in use, the position of the supporting arm 30 is essentially parallel with the plane of the upper surface of rails 17,34.

The supporting arm 30 has a yoke-shaped section 36, which is positioned closest to the frame 12 and that has an articulated attachment 31 to the frame at two points. By this means, the yoke-shaped section can be swung up towards the frame 12 to a position where the said yoke- shaped section is essentially parallel with the main plane of the frame, as shown in the dashed position in fig. 1. The supporting arm 30 also has a triangular-shaped section 38 that forms that part of the supporting arm 30 closest to the extra wheel 32, i. e. triangular-shaped section 38 supports the extra wheel so that it rotates. The yoke-shaped section 36 and the triangular-shaped section 38 are joined to each other by an articulated manner by means of a folding joint 40, which is shown in detail in fig. 1. With the supporting arm 30 in its working position, see fig. 1, the folding joint 40 is locked in position so that it cannot fold by means of a locking device 42

that is of conventional design and therefore not described in more detail. In its working position, the supporting arm 30 is therefore rigid outwards from its articulated attachment 31 to the frame 12. When this occurs, note that the folding joint is so designed so that the supporting arm cannot be forced further downwards, i. e. the folding joint cannot take up a position that lies below a plane passing through the supporting arm's 30 attachment points to the frame 12 and the extra wheel 32.

In the working position of the supporting arm 30, the articulated attachment 31 to the frame 12 is locked, which means that once in its working position, the supporting arm 30 cannot be swung relative to the frame 12. By studying fig. 1 in detail, it will be evident that the supporting arm's 30 articulated attachment 31 to the frame 12 is provided with a locking device 43 of the same type as locking device 42. As the supporting arm 30 is attached to the frame with two articulated joints, it is preferable that a locking device 43 is arranged at both attachment points 31.

When the supporting arm 30 is to be transferred from its working position to its non-working position (the dashed position in fig. 1), the locking devices 42 and 43 for the folding joint 40 and articulated attachment 31 respectively are released and, as previously described, the yoke-shaped section 36 of the supporting arm 30 is transferred to a position where the said section 36 is essentially parallel with the main plane of the frame 12. In connection with this, the triangular section 38 of the supporting arm 30 is lowered to a folded position shown by the dashed lines in fig. 1. By means of the folding joint between the cycle frame 12 and the extra wheel 32, the supporting arm 30, when non-active, thus takes up a folded position that occupies relatively little space in terms of both height and width.

The partly cut-away view shown in fig. 4 of a wheel 14,16 of the rail cycle 10 according to the invention shows that the said wheels 14,16 have, in the traditional manner, a hub 44 from which spokes extend out to a rim 48 that supports an air-filled tyre 50 in contact with one of the rails 17 of the railway track. Tubular housings 52 are mounted at a specified centre-to-centre distance along the circumference of the rim 48 by an appropriate means, in the shown embodiment, by welding. The tubular housings extend across the main plane of the wheel 14,16. The tubular housings 52 accommodate bolts 53 that are threaded at the opposite end to the bolt head 54. An initial guide plate 56 is mounted between the bolt head 54 and the closest end of the tubular housing. This said guide plate 56 is provided with holes that, in the correct mounting position of the initial guide plate 56, are located directly opposite the tubular housings

52. The dimension of the holes in the initial guide plate 56 is such that the bolt 53 but not the tubular housing 52 can pass through the said hole. This means that even the initial guide plate 56, in its mounted position, will be located between the bolt head 54 and the closest end of the tubular housing 52. In what is in principle the equivalent manner, a second guide plate 58 is mounted between the other end of the tubular housing 52, whereby in this case, the said guide plate 58 is mounted between the said other end of the tubular housing 52 and a nut 60 threaded onto each bolt 53. In the same way as the initial guide plate, second guide plate 58 also has holes arranged in it. When the nuts 60 are tightened, the initial and second guide plates 56,58 will be clamped tightly between the respective ends of the tubular housing and on one side, the bolt heads 54, and on the other side, the nuts 60. As is evident from fig. 4, the guide plates 56,58 surround the tyre on both sides and extend radially somewhat beyond the tyre's 50 outer circumference to, by so means, interact with the rail 17 so that a fully acceptable guiding of the wheels 14,16 relative to the rail 17 is achieved.

The guide plates 56,58 extend radially so that, with normal air pressure in the tyre 50, the guide plates 56,58 overlap the rail 17. This ensures that the tyre 50 does not slide off the rail in normal operation. In this way, the extra support wheel 32 does not require its own guiding device as the guiding of the wheels 14,16 ensures that the extra wheel 32 is always positioned exactly above the associated rail 34.

By filling the tyre 50 with air, a comfortable ride is assured, even when the rail cycle 10 travels along the railway track. The extra wheel 32 is preferably also filled with air as this will further improve the quality of the rails cycle's 10 ride. As there are joints at regular intervals along the rails 17,34 that comprise the railway track, it is especially advantageous with air-filled tyres as these will cushion any differences in elevation that can occur at these joints.

Within the scope of the invention, it can even be considered designing the guiding device so that it is integrated with the rim of the wheel, especially in cases where the rim and guiding device are injection moulded in a suitable plastic material. The present invention is, however, not limited to the description above and that shown in the drawings, but can be changed and modified in a number of different ways within the scope of the intention of the invention given in the claims.