GB2226286A

GB2226286A - Track-guidable, bidirectional articulated vehicle, eg. bus

Info

Publication number: GB2226286A
Application number: GB8927552A
Authority: GB
Inventors: Diether Von Scarpatetti; Klaus Niemann
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1988-12-12
Filing date: 1989-12-06
Publication date: 1990-06-27
Anticipated expiration: 2009-12-06
Also published as: JPH02200507A; GB2226286B; FR2640220B1; SE8904123D0; SE468471B; DE3841772C1; GB8927552D0; IT8948623A0; FR2640220A1; IT1237229B; JPH078645B2; BR8906396A; SE8904123L

Description

A 1 j- ' k :7,::i - - ( P, 6> 1 Track-guidable, bidirectional articulated

vehicle, -Particularly an articulated bus The invention relates to a track-guidable, bidirectional articulated vehicle, which vehicle has vehicle sections, vehicle joints and vehicle axles which, seen transversely to the direction of travel are centresymmetrically constructed or arranged, which vehicle or bus furthermore exhibits one fully equipped driver's cabin each at both vehicle ends and is optionally fully operational in one or in the other direction of travel, all vehicle axles furthermore being equipped with lockable wheels, the vehicle axles located nearest to the vehicle ends - outer axles - being constructed as driving axles, furthermore with lateral-guidance rollers which are arranged close to the ground in the wheel area and interact with track-determining lateral-guidance runners along the roadway, which are held in unchangeable lateral position with respect to the wheel plane of the respective lockable vehicle wheels via wheel-encircling holding arms and which laterally project outwards past the vehicle wheels,which is found to be known, for example, from the published lecture manuscripts of a public seminar on 6th and 7th October 1988 on the subject "Local Passenger Traffic - Traffic Requirements and Means of Transportation"; in this connection, reference is made to the contribution by Fo'rster "Die O-Bahn - ein L8sungsvorschlag der Daimler- Benz AG filr den OPNV" (The above-ground railway - a proposed solution for public local transport by Daimler-Benz AG), particularly to Figure 20c. The articulated bus shown there has also been presented to the public at several traffic exhibitions.

The known articulated bus is constructed of conventional bus parts. In particular, this is overall a three-section bus in which the two outer sections are in each case constructed as two- axle buses with open rear between which a bridge section without axles is suspended.

X 2 The known bus can only be used for track-bound operation, which is of considerable disadvantage even with a dense track network because the bus cannot travel a single metre without being bound to a track. Even short interruptions of the lateral-guidance runners at the side necessitate track guidance by a further track guidance system installed at the vehicle and along the roadway; for example, a track groove system arranged below the roadway surface could be provided for this purpose. However, this means additional costs for the vehicles and the track routes. In addition, an essential advantage of the buslike light-weight construction and the road-usable pneumatic tyring is lost; the prior bus cannot be flexibly operated in an area-covering manner.

Although the literature reference mentioned initially also shows articulated buses which are optionally track-bound or can be used with free manual steering, that is to say bimodally these vehicles are only fully operational in a single direction of travel, that is to say they cannot be bidirectionally used. However, the requirement of fully operational usability in both directions of travel is necessary, particularly in belowground operation or in operation on relatively long trackproviding routes with separate track bed. This is because it is intended to stop the trip at any point and continue it in the opposite direction of travel. A vehicle which can only be used in one direction of travel must continue to travel in the same direction'until it reaches the next exit possibility, look for an area which is sufficiently large for a turning manoeuvre or a corresponding street rectangle in manually steered operation, return to the track-providing route and travel back to the end. This represents not only unnecessary loss of time but also waste of fuel and operating hours for the vehicles. Apart from this, it may not be possible at all to perform such a manoeuvre when the road track is blocked by a faulty vehicle which is located ahead.

it is true that German Patent Specification

3 3,333,476 shows a vehicle which can be used both bidirectionally and bimodally and which is designed as recovery vehicle for track-guided buses. It is also easily conceivable to construct such an equipment vehicle as a bus for public local passenger traffic. It would be disadvantageous, though, that the carrying capacity of such singlesection vehicles is only quite restricted especially since driver's cabins are also mounted at both front ends of the vehicle.

The present invention seeks to develop the known track-guidable and bidirectional articulated bus to such an extent that it can also be bimodally operated.

According to the present invention, there is provided a track-guidable, bidirectional articulated vehicle, which vehicle has vehicle sections, vehicle joints and vehicle axles which, seen transversely to the direction of travel are centre-symmetrically constructed or arranged, which vehicle or bus furthermore exhibits one fully equipped driver's cabin each at both vehicle ends and is optionally fully operational in one or in the other direction of travel, all vehicle axles furthermore being equipped with lockable wheels, the vehicle axles located nearest to the vehicle ends outer axles - being constructed as driving axles, furthermore with lateralguidance rollers which are arranged close to the ground in the wheel area and interact with track-determining lateral- guidance runners along the roadway, which are held in unchangeable lateral position with respect to the wheel plane of the respective lockable vehicle wheels via wheelencircling holding arms and which laterally project outwards past the vehicle wheels, wherein a) the articulated vehicle is constructed in two sections having only one centrally arranged vehicle joint and three vehicle axles; only the two outer axles are provided with lateralguidance rollers, being arranged circumferential side b) lateral-guidance only on of the rollers also one side on the vehicle wheels in each X 4 d) 1 f) h) case pointing towards the vehicle end; each of the outer axles, can also be manually steered from the drivel-'s cabin but in each case only the one, which is in each case the nearest; all vehicle axles are constructed in such a manner that the respective lockable vehicle wheels can be locked in the straight-ahead position; the centre vehicle axle is approximately coincident with the vehicle joint and - in deviation from the centre-symmetrical overall vehicle construction - is pivoted at one of the two vehicle sections - two axle vehicle section - in a manner known per se non rotatably, seen in plan view, the other veiele section defining a single-axle vehicle section in the text which follows; when its blocking in the straight-ahead position is cancelled, the centre vehicle axle can be independently steered in dependence on the bending angle between the two-axle and the single-axle vehicle section in such a manner that the lockable vehicle wheels of the centre vehicle axle are always aligned in parallel with the single-axle vehicle section; g) control measures which automatically become effec tive after the selection of the direction of travel ensure that the outer axle which is in each case at the front in the selected direction of travel is enabled to be steerable ahd that, at the same time, the vehicle wheels of each case at the rear in the outer axle which is in the selected direction of travel is locked in the straight-ahead position; further control measures which also automatically become effective after the selection of the direction of travel also ensure that when the direction of travel is selected to be in the direction of the two-axle vehicle section, the vehicle wheels of the centre vehicle axle are locked in the straightahe..d position and that, in contrast, when the direction of travel is selected to be in the direction of the single-axle vehicle section, automatic steerability of the centre vehicle axle is established and enabled. The basic concept in this consists of a completely unusual arrangement and development of the centre axle according to the characterizing part-features e and f. In addition, some control measures must be taken which are initiated by the corresponding selection of the direction of travel.

Suitable developments of the invention can be found in the subclaims.

An embodiment of the invention will now be explained by way of example with reference to the drawings, in which:

Figures and 2 Figure 3 Figures and 5 Figure 6 Figure 7 Figure 8 1 4 show a side view (Figure 1) and plan view representation (Figure 2) of a track guidable, bidirectional articulated bus, shows a front view of the articulated bus according to Figures 1 or 2 in an enlarged representation, show plan views of the same bus when travelling through a tight curve in a counterclockwise direction (Figure 4) and in a clockwise direction (Figure 5), the two-axle bus section being shown in the left-hand half of the picture in both cases, shows a perspective diagrammatic representation of the centre vehicle axle and its steering, shows an individual representation of the centre vehicle axle after cancellation of the blocking in the straight-ahead posi tion and enabling of the steerability in dependence on the bending angle, and shows an individual representation of the mounting of a further jostling roller.

1 6 The articulated bus 1 shown in the figures is trackguidable on trackproviding roadways 32 and 33 by means of lateral-guidance runners 28 and 28' installed on the side. In addition, the vehicle is centresymmetrically constructed with respect to a centre plane 2 which is transverse to the direction of travel and is imagined in the centre of the overall vehicle; the various vehicle sections 3 and 4 and the vehicle axles 6, 61 and 7 and the vehicle joint 5 are arranged or constructed symmetrically with respect to this centre plane. At both vehicle ends, one fully equipped driver's cabin 12 and 12' each is provided so that the vehicle is optionally fully opera- 41 or in the opposite direction of travel 41', respectively. All vehicle axles 6, 6' and 7 are equipped with lockable steerable wheels; the outer axles 6 and 6' arranged in the area of the vehicle ends are also constructed as driving axles which, however, is not shown. To this extent, reference can be made, for example, to the previously quoted German Patent Specification 3,333,476. To provide the possibility of track guidance, lateral-guidance rollers 13 are arranged close to the ground in the wheel area, which rollers interact with track-determining lateral- guidance runners 28 along the roadway. The lateral-guidance rollers 13 are held in unchanged lateral position with respect to the wheel plane of the respective lockable vehicle wheels 8 and 8' via wheel-encircling holding arms 14. The lateralguidance rollers 13 laterally project past the vehicle wheels 8, 8' towards the outside by about 25 to 75 % of the diameter of the lateral-guidance rollers 13.

To be able to form, with supportable expenditure, sufficiently large articulated buses which can be used not only bidirectionally but also bimodally, the articulated bus is only constructed in two sections having only one centrally arranged bus joint 5 and the three vehicle axles 6, 7 and 6' mentioned. The said lateral-guidance rollers 13 ore only provided in the area of the two outer axles 6 and 6'. In addition, the lateralguidance rollers are only tional in one direction of travel arranged on one side on the circumferential side of the vehicle wheels 8 and 8't respectively pointing in each case towards the vehicle end. As a result, the lateralguidance device can be constructed not only relatively simply and easily but the lateral force is not transmitted via the lateral-guidance rollers but via the tyre contact area into the roadway. Each of the outer axles 6 and 6' can also be steered, in addition to via the lateralguidance rollers, manually freely by the manual steering wheel 15 and 15' of the driver's cabin 12 and 12', respectively; however, manual steerability of the outer axles is in each case only possible from the nearest driver's cabin. All vehicle axles, that is to say the two outer axles 6 and constructed in wheels 8, 8' and position.

To provide the possibility of centre-symmetrical vehicle construction even with three vehicle axles and also to ensure an approximately similar travelling characteristic in the two directions of travel, the centre vehicle axle 7 is arranged to be approximately coincident with the bus joint 5. In addition, the centre vehicle axle 7 - in deviation from the centre-symmetrical overall vehicle construction - is non-rotatably pivoted at one of the two bus sections which will be designated as two- axle bus section 3 in the text which follows, in a manner known per se, seen in plan view; th other bus section must be correspondingly considered as single-axle bus section 4. When its blocking in the straight-ahead position is cancelled, the centre vehicle axle 7 can be independently steered in dependence on the bending angle between the two- axle (3) and the single-axle bus section 4 in such a manner that the lockable vehicle wheels 9 of the centre vehicle axle 7 are always aligned in parallel with the single-axle bus section 4.

Apart from the constructional developments of the articulated bus hitherto mentioned, certain control 6' and the centre vehicle axle 7 are such a manner that the lockable vehicle 9 can be blocked in the straight-ahead 1 8 measures must also be taken which are executed automatically during or after the selection of the direction of travel. The direction of travel is selected by the driver entering one of the corresponding driver's cabins 12 or 12' and there actuating a corresponding switch by means of a key and thus activating the respective driver's cabin.

Of the measures following, only the effect will be described, the control measures as such should be familiar to the expert in the field. On the basis of the selection of such a direction of travel 41 or 41', the steerability of the outer axle 6 or 6' which is in each case at the front must be enabled. At the same time, the vehicle wheels 8' or 8 of the outer axle 6' or 6, respectively, which is in each case at the rear in the selected direction of travel must be blocked in the straight-ahead position. In this connection, reference can also be made to the previously quoted German Patent Specification 3,333,476. Accordingly, the device for blocking the steerable vehicle wheels in the straightahead position essentially consists of a pivoted quadrangle to be rangle and their implementation in the area of the steering gear which is arranged fixed with respect to the frame. This pivoted quadis formed of the steering gear arm of the steering gear, of a rocking arm which is also supported to be fixed to the frame and of a coupler w hich joins the two to one another in a pivoted manner at their free end. The rocking arm itself is movably supported in a joint which is fixed with respect to the frame. At tfle freely steerable vehicle axle, the coupler is located with its two ends at the outer end of the steering gear arm and of the rocking arm. The latter then also performs the movement of the steering gear arm during the steering.

In order to be able to lock the steerable vehicle axle in the straightahead position of the steerable vehicle wheels, the free rocking arm joint is supported to be displaceable on the rocking arm in such a manner that it can be displaced in coincidence with the rocking arm joint fixed with respect to the frame. The coupler is 1 9 dimensioned to have just such a length that with coincident arrangement of the free rocking arm joint with the frame-fixed rocking arm joint, the steering gear arm is just held fixed in the neutral position in which the vehicle wheels of the associated axle are in the straightahead position. This neutral position is automatically produced by displacing the free rocking arm joint on the rocking arm in the direction of the rocking arm joint at the frame side, even if the vehicle wheels should be outside such a steering position. In order to provide the possibility of remote- control displacement of the free rocking arm joint on the rocking arm, the rocking arm is provided with a guide in which a corresponding sliding block which carries the free rocking arm joint is displaceable. Thq latter carries a nut which engages a threaded spindle which, in turn, can be motor driven under remote control. The corresponding displacement drives for the free rocking arm joint of the two outer axles 6 and 6' are coupled in opposite direction to a power supply in such a manner that the two blocking devices are in each case driven in the opposite direction and thus only one of the two outer axles is steerable and the other one in each case is blocked in the straight-ahead position.

Further control measures, which also automatically become effective after the selection of the direction of travel also ensure that when the direction of travel is selected to be in the direction 41 of the two-axle bus section 3, the vehicle wheels 9 of the centre vehicle axle 1 7 are locked in the straight-ahead position. The individual constructional solution of this will be described below in connection with the explanation of Figures 6 and 7. When the direction of travel is selected to be in the direction 41' of the single-axle bus section 4, in contrast, automatic steerability of the centre vehicle axle 7 is established or enabled. In this case, the vehicle wheels 9 of the centre vehicle axle 7 are always set to be in parallel with the preceding singleaxle vehicle section 4.

The usual construction of a steerable vehicle axle consists of an axle bracket 10 at the ends of which steering knuckles 11 are rotatably pivoted via an approximately vertical joint 24. The steering knuckles in each case exhibit a track lever 19 which approximately extends in the longitudinal direction of the vehicle. The free ends of the. track lever exhibit joints 24 which are pivotably connected via a track rod 18 extending in parallel with the axle bracket 10. The pivoted quadrangle formed in such a manner is usually constructed to be trapezoidal in the straight-ahead position of the vehicle wheels. This ensures that the vehicle wheel which is in each case on the inside in a curve is turned slightly more than the vehicle wheel on the outside of the curve. This trapezoidal formation of the pivoted quadrangle is kept throughout in the case of the outer axles 6 and 6'. A symmetrical behaviour of the two outer axles with respect to vehicle dynamics is ensured by the fact that they are arranged at equal distances from the centre plane 2 and that they are alternately steerable or blocked in the straight-ahead position. In contrast, the conditions are different in the case of the centre vehicle axle 7. So that this axle, too, is provided with symmetrical behaviour for both directions of travel 41 and 41' with respect to vehicle dynamics, the pivoted quadrangle is constructed as a rectangle in the straight-ahead position of the vehicle wheels 9 in the case of this axle. In addition, at least the vehicle wheels 9 of the centre vehicle axle 7 do not exhibit any toe-in whatever.

The steerability or blockability of the centre vehicle axle 7 is shown in greater detail in Figures 6 and 7. The axle bracket 10 of the centre vehicle axle is - as has been said - pivoted in conventional manner at the twoaxle bus section 3 via a pair of trailing arms 16 and a further pair of A-arms 17 transversely to the longitudinal axis of this bus section. Although the centre vehicle axle in this arrangement can carry out spring-compressionrelated rolling and lifting movements compared with the 1 11 frame of the two-axle bus section 3, all other degrees of freedom compared with the frame of the two-axle bus section 3 are cancelled.

For the sake of clarity, the vehicle suspension is not shown in Figure 6. The bus joint 5 between the two vehicle sections 3 and 4 is coincident with the centre plane 2 of the overall vehicle and with the axle bracket 10 of the centre vehicle axle 7 in the plan view. The vehicle joint 5 is essentially a turntable mount known per se which, although it allows pitching and yawing of the two bus sections 3 and 4 with respect to one another does not allow mutual rolling movements; to that extent, the vehicle axles compensate for roadway unevennesses. A loadreceiving plate 3 is held via a cantilever at the two-axle bus section 3 or at its frame which also carries a pivot pin 37. Onto this load-receiving plate, a support plate 35 of the single-axle bus section 4 is placed which, in turny can be rotated within limits around a pair of horizontal pivot supports 38 in order to allow mutual "pitching" of the bus sections 3 and 4. The axis of the horizontal pivot supports 38 is also in the area of the centre plane 2.

In order to be able optionally to cancel the steerability of the centre vehicle axle and block it again as in the straight-ahead position or in order to be able to steer it in dependence on the bending angle, an intermediate track arm 20 is attached to the axle bracket 10 which pivotably engages the split track rod 18 in the exemplary embodiment shown. Thit intermediate track arm 20 can then, on the one hand, mandatorily be coupled to the frame of the two-axle bus section 3 or, on the other hand, mandatorily be coupled to the support plate 35 which, in turn, is permanently joined to the frame of the singleaxle bus section 4. For this purpose, the two coupling rods 21 and 22 are provided which are connected via angle arms of the intermediate track arm 20 to the twoangle bus section 3, on the one hand, and, on the other hand, to a vertical steering shaft 40; the latter carries laterally angled arms at its two ends. In the area of the top end of 12 the steering shaft 40, the rotational movement of the support plate 35 is transferred via a link rod 39 to the corresponding angled arm of the steering shaft 40 so that the steering shaft 40 always also performs the rotating movement of the support plate 35. The two coupling rods 21 and 22 are constructed as switchable sections and can optionally be switched as length-invariable rigid rods or as telescoping sections.

For this purpose, the coupling rods, which are of identical construction with respect to one another, exhibit a cylindrically loadable cylinder 42 which will still be discussed in detail below. In addition, a sliding rod 43 is axially. displaceable centrally in the coupling rod and is sealingly passed through the axial cover of the cylinder 42; a receiving tube is provided axially adjoining the cylinder 42, into which the free end of the sliding rod 43 can plunge. At the end of the receiving tube, a cylinder-side pivoting eye of the coupling rod is attached, whereas the respective pivoting eye at the sliding rod 43 is arranged at the other end of the coupling rod. In the axially central area of the cylinder 42, a cylinder-side collar 45 is attached; in addition, the sliding rod 43 also carries a rod-side collar 46. This is arranged in its axial position in such a manner that it accurately coincides with the position of the cylinderside collar 45 in the straight-ahead position of the vehicle wheels of the centre vehicle axle 7. In addition, the two collars 45 and 46 corre;pond with respect to their axial dimensions. The two collars 46 and 47 exhibit great clearance with respect to one another in the radial direction; thus they do not have any piston effect. In the interior of the cylinder 42, two disc-shaped flying pistons 44 are also arranged on this and the other side of the two collars 45 and 46 mentioned, which pistons are sealed, on the one hand, on the inside of the cylinder 42 and, on the other hand, on the peripheral side of the sliding rod 43. By applying pressure to the two pressure spaces located on the other side of the disc-shaped flying 13 pistons 44 as is shown in the right-hand half of Figure 7 for the coupling rod 22, these are displaced in the direction of the cylinder- side collar 45 during which process they mandatorily carry along the rod- side collar 46. The oil displaced between them is displaced into the pump sump via the centre connection. In this manner, the sliding rod 43 with the rod-side collar 46 can be axially rigidly coupled to the cylinder 42 and the cylinder-side collar 45.

In addition, a corresponding rod length of the coupling rod 22 is also moved in against external resistance. The two coupling rods 21 and 22 are hydraulically crosslinked so that the flying pistons 44 of one coupling rod assume just the other extreme position than in the case of the other coupling rod. Whilst thus one coupling rod is switched "rigid", the other one is switched to "axially with play" and conversely. The state shown in Figure 7, in which the right-hand coupling rod 22 is rigidly switched through, corresponds to the condition in which the intermediate track arm 20 is mandatorily coupled to the support plate 35 and thus the steerability of the centre vehicle axle is established in dependence on the bending angle between the two bus sections. In the case of an opposite hydraulic loading of the pressure spaces of the coupling rods 21 and 22, the left-hand coupling rod 21 would be rigidly switched through and the right-hand coupling rod 22 could have axial play. This would correspond to a blocking of the steerability of the centre vehicle axle in the straight-ahead position of the vehicle wheels. If these are not in the straight-ahead position during the selection of the direction of travel, they would be displaced into the straight-ahead position by the - pressure force of the dish-shaped pistons 44 and held in this position.

In the text which follows, the travelling operation in the two different directions of travel will be discussed with reference to Figures 4 and 5. In the two figures, the two-axle bus section 3 is shown on the left- 14 hand side and the single-axle bus section 4 on the righthand side. In Figure 4, travelling operation is shown in the direction of travel 41, that is to say with the 3 which is most similar to two-section bus with leading two-axle bus section the operation of a conventional single-axle unsteered trailer. The axles of all the vehicle wheels meet in a common centre even though all the vehicle wheels run along different turning cycles. Above all, it can be seen that the angle of lock of the two vehicle wheels 8 of the leading outer axle 6 has different sizes. In the travelling mode in the opposite direction of travel 411 with leading single-axle bus section 4, shown in Figure 5, it is similar to the travelling condition according to Figure 4 with respect to the two outer axles 61 and 6. An essential difference mainly consists with respect to the centre vehicle axle 7. Although the axle bracket of the centre vehicle axle 7 is aligned in parallel with the centre plane 2, as before, the vehicle wheels 9 of this axle are locked in parallel with the leading single-axle bus-section 4 due to a bending-angledependent steering of the centre vehicle axle. The angles of lock of both vehicle wheels 9 are of the same amplitude so that the wheel axles of the two vehicle wheels are parallel to one another. This is attributable to the circumstance that the pivoted quadrangle of the centre vehicle axle 7 is constructed as a rectangle in the straight-ahead position of the vehicle wheels 9. Although the parallel alignment of the two vehicle wheels 9 theoretically creates a small rolling error in the travelling mode of Figure 5, the tangent at the wheel rolling track exhibits a small slip angle with respect to the wheel plane. For the rest, the slip angles of the two opposite vehicle wheels are opposite to one another and of the same magnitude; both vehicle wheels are forced away in the direction of the vehicle centre in the sense of a toein angle. This results in relatively stable running of the centre vehicle axle with bending-angle-dependent wheel lock. If, incidentally, the rear two-axle bus section 3 z should change the bending angle in an uncontrollable manner compared with the leading bus section due to the influence of centrifugal force or due to brake pull or the like during the trip in travelling operation accordingto Figure 5, the vehicle wheels 9 of the centre vehicle axle 7 remain aligned in parallel with the single-axle bus section 4. Although such a breaking-out of the rear bus section changes the bending angle and with it also the looking angle of the vehicle wheels 9 relative to the axle bracket 10, the vehicle wheels 9 remain aligned precisely in parallel with the leading bus section 4 as has been said. The reason for this is that when the steering of the centre vehicle axle is enabled, the position of the intermediate track arm 20 remains unchanged relative to the single-axle bus section 4, whereas the state of rotation of the axle bracket 10 is changeable in relation to the single-axle bus section 4. This relative change also produces the change in position of the lockable wheels 9 Thanks to relative to the axle bracket 10 as mentioned. the precise parallel alignment of the vehicle wheels 9 with respect to the single-axle bus section 4 with all bending angles, the vehicle behaviour of the bus section 4 remains the same independently of the bending angle. If, in contrast, the pivoted quadrangle of the centre vehicle axle 7 were constructed to be trapezoidal in the conventional manner, small toe-in angle changes would occur with a breaking-out of the rear bus section 3 which would also influence the running behaviour of the front bus section 4. This would impair the running behaviour of the entire articulated bus.

The usual track guidance of buses with laterally mounted lateral-guidance rollers is that the roadway contains on both sides lateral-guidance runners which interact with the lateral-guidance rollers provided on both sides on the vehicle. With a double track with a separate driving track for each direction of travel, this means that the two driving tracks are separated from one another by a centre runner. As a result, passing or 16 travelling past a vehicle standing on the same driving track is not possible at any arbitrary position.

To allow safe travelling operation even without such a centre runner separating the two roadways 32 and 33 for the direction of travel 41 and the direction of travel 411, respectively, the vehicle shown provides, in addition to the first lateral-guidance rollers 13 previously mentioned, further lateral-guidance rollers 27. These are held movably in such a manner that each of the further lateral-guidance rollers 27 can be optionally lowered into a lowered operating position - shown in continuous lines in Figure 3 - or raised into a raised rest position projecting past the lateral-guidance runner 28 along the roadway, independently of the first lateral-guidance roller 13; this rest position is shown dashed in Figure 3.

The driver's station inside the driver's cabin 12 is usually arranged away from the centre in the direction of the centre of the roadway of a street with two-way traffic. In the case of right-hand traffic, this is the left-hand vehicle side and in the case of left-hand traffic this is the right-hand vehicle side. The driver's side of the bus sections 3 and 4, respectively, is designated with the reference number 25 and 25' and the side facing away from the driver is designated by 26 and 26'. The additional lateral-guidance rollers 27 are used for maintaining a safe unilateral track-guidance operation, that is to say the vehicle should be guided in a form-locking manner and held on track both in the direction of the outside of the roadway and in the direction of the centre of the roadway even though a lateral-guidance runner exists on only one side. Nevertheless, passing a vehicle standing in the track with manual steering is easily possible. The lowered operating position of the further lateral-guidance roller 27 mentioned is at approximately the same level as the operating position of the associated first lateral-guidance roller 13; in the longitudinal direction, the further lateral-guidance roller 27 is at approximately the same position as the first lateral-guidance roller 13. In the width direction, the further lateral-guidance roller 27 is arranged outside the first lateral-guidance roller and even exhibits a clear distance a from the outer circumference of the first lateral-guidance roller which corresponds to the runner thickness of the lateral-guidance runner 28 along the roadway. This exhibits a defined and constant thickness a and a specifically shaped track-determining inside 29 and a corresponding outside 30. When the further lateralguidance roller 27 is lowered, it makes contact with the outside 30 of the lateral-guidance runner 28 and thus takes over the track-keeping of the vehicle in the direction of the roadway centre 34. The inside 29 of the lateral-guidance runner, which interacts with the first lateral-guidance roller 13, takes over the track-keeping of the articulated bus in the direction of the roadway outside. The further lateral-guidance rollers 27 are only mounted at diagonally opposite sides, namely in each case on the vehicle side 26 and 26' facing away from the driver. When passing a vehicle which is travelling ahead very slowly or when passing a vehicle standing on the same driving track, the driver changes to the opposite roadway. For this purpose, he raises the further lateral-guidance roller into the rest position, changes to the opposite roadway in manually steered- operation this would be roadway 33 in the example of Figure 2 - contacts the inside of the lateral-guidance runner 281 with the first lateral-guidance roller 13 on the driver's side and travels unilaterally track-guided past the advanced vehicle with a slight bias to the left on the steering. After completing the passing manoeuvre, he changes back to driving track 32, makes contact with the lateral- guidance runner 28 with the first lateral-guidance roller 13 of the vehicle side 26 facing away from the driver in manually steered mode and again lowers the further lateral-guidance roller 27 to the outside 30 of this lateral-guidance runner. The trip can subsequently be continued with fully track-bound operation.

18 The further lateral-guidance roller 27 can be moved up and down in a straight line but it can also be supported, as shown in Figure 3, on a rotating lever 31 which, in turn, is rotatably pivoted at the holding arm 14. This results in a low construction and stable movability which can also be rotated by means of an actuator of simple construction,. for example a pneumatically loadable actuating cylinder.

In the selection of the direction of travel, it is not only the respective leading outer axle which must be made steerable as mentioned and the respective outer axle located at the rear which must be blocked in the straightahead position, but it must also be ensured for the case where further lateral-guidance rollers 27 are provided at the bus that the adjustability of the further lateralguidance roller is only enabled at the outer axle which is at the front in the selected direction of travel; at the same time, it must be assured that the further lateralguidance roller 27 is moved into the raised rest position and blocked in this position at the outer axle which is at the rear in the selected direction of travel and is blocked in the straight-ahead position. The passing manoeuvres described above in which the driver temporarily moves past the other vehicle in manually steered operation are instances of heightened attention. In order to provide some support in this case from the vehicle control mechanism, it can be suitably provided that the further lateral-guidance roller 27, the adjustability of which is enabled, is functionally locked in the end position which happens to exist in each case, that is to say in the lowered operating position or in the raised rest position, but that this functional locking can only be cancelled when certain criteria are present so that the attention of the driver is drawn or ensured.

These criteria of travelling conditions can be, on the one hand, a particular travelling speed; this is intended to ensure that the transition to free manual steering or the transition from manuallysteered operation 19 to track binding is only carried out below a particular limit of speed. Another travelling criteria which may also be additionally applied can be the lateral force of the associated first lateral-guidance roller 13 or of the corresponding holding arm 14; naturally, a corresponding lateral- force sensor would have to be built into the holder of the lateral- guidance roller, if necessary for this. If it is ensured that the lateral force of the lateral-guidance roller or of the holding arm is above a particular threshold value, the functional locking of the further lateral- guidance roller 27 can be cancelled in the respective end position and a change of travelling condition can be enabled. If the driver intends - starting with track-guided operation with lowered functionally locked further lateral-guidance roller 27, to change into manually-steered operation, the monitoring of a particular lateral force ensures that, on the one hand, the attention of the driver is ensured - the lateral-force threshold value must be "fetched" by a deliberate bias of the steering towards the lateral-guidance runner 28; it furthermore ensures that when the further lateral-guidance roller 27 is raised the steering of the bus still follows the lateral-guidance runner and is not already biased in the direction of the roadway centre, which may cause uncontrolled steering of the bus away towards the roadway centre under certain circumstances. When the travelling mode returns to track mode - starting from manuallysteered travelling conditioh with raised and also functionally locked further lateral-guidance roller 27, the threshold value of the lateral support force of the lateral-guidance roller 13 must also be "fetched" by deliberate biasing of the vehicle steering in the direction of the lateral-guidance runner 28. This ensures that the vehicle and its steering are in reliable contact with the lateral- guidance runner.

Track guidance of the vehicle is only effected via the lateral-guidance rollers 13 or 27 of the outer axle 6 or 6', respectively, which in each case leads. The lateral-guidance rollers of the respective rear outer axle, on the other hand, are functionless. There may be an occasional requirement for raising these unneeded lateralguidance rollers out of the range of influence of the roadway and of the lateral-guidance runner into a rest position. There are enough examples in the prior art for such a constructional solution of the problem of raising the lateral-guidance rollers into a rest position or lowering them into an operating position which is why this will not be discussed in greater detail here. It is only pointed out for this case that here, too, appropriately designed control measures which automatically become effective after the selection of the direction of travel, ensure that the lateral-guidance rollers which are located at the front in the direction of travel are lowered into the operating position and at the same time the lateralguidance rollers which are at the rear in the direction of travel are raised into the rest position.

As an alternative to raising the lateral-guidance rollers 13 and, if necessary, 27 into a rest position or lowering them into the operating position, a transferring of the lateral-guidance rollers which are not needed in each case in the area of the rear outer axle into a socalled jostling position can also be taken into consideration. Once the rear outer axle is blocked in the straight-ahead position, it is not possible to change the straight-ahead position of the vehicle wheels by means of an action of a lateral forge on the lateral-guidance roller 13. Instead, when the lateral-guidance roller 13 rests against the lateral-guidance runner, the rear outer axle is laterally supported against the latter and jostles the vehicle away in the direction of the centre of the roadway. Such a jostling can occur in the area of curves. When travelling slowly through a curve, a jostling can occur in the inside of the curve which can easily be seen in the representations of Figures 4 and 5. When travelling quickly through curves, the rear section of the vehicle is displaced outwards as a result of the centrifugal force so C 1 21 that in this case a jostling can be observed on the outside of the curve. However, in order to provide the possibility of building up a certain lateral force by means of a slip angle, the jostling rollers will not exhibit precisely the same overhang as the track-determining lateral- guidance rollers but will be offset as far back as possible. However, the jostling rollers must still slightly project over the outside side wall of the wheel tyre so that these cannot scuff against the lateralguidance runner. Thus, in order to be able to change the lateral-guidance rollers at the respective rear outer axle in the direction of travel into jostling rollers, the lateral-guidance rollers 13 are advantageously mounted movably at the holding arms 14 carrying them, in such a manner that - starting from an operating position which projects by about half the diameter of the lateralguidance roller past the tyre side wall of the associated vehicle wheel 8 or 8' - they can be retracted into a jostling position which is retracted at the same level but still projects by about 1 em past the outside tyre side wall. In such a case, too, control measures becoming automatically effective with the selection of the direction of travel should ensure that either the operating position or the jostling position of the lateral-guidance roller 13 is set depending on the position of the outer axle 6 or 61 in relation to the direction of travel selected. Such an equal-level transverse displacement of the lateral-guidance roller caA be produced, for example, by an eccentric support and a rotating movement of the eccentric shaft.

The jostling forces which act on guidance roller 13 which is mounted in the the lateralmanner described and is active as jostling roller must be removed via the steering linkage of the rear outer axle which is blocked in straight-ahead position. Although it will be possible to transfer a significant proportion of the lateral forces via the so-called tyre contact area due to the fact that there, too, a slip angle between the wheel 1 22 plane and the instantaneous direction of travel occurs, the proportion of lateral force produced in excess of this must be absorbed as mentioned - via the jostling roller and the blocked steering linkage. To relieve the steering linkage of such forces, it may be appropriate to arrange in the area of the outer axle for each vehicle wheel 8, 8'. a further jostling roller 47 which is mounted via a further holding arm 48 opposite to the lateral-guidance roller 13, that is to say towards the vehicle centre plane 2, but at the same level as the lateral-guidance roller 13. This further jostling roller 47 is from the start mounted immovably in the lateral direction at jostling position, that is to say with only a very slight.lateral overhang over the outside tyre side wall of the vehicle wheel 8, 8'. However, so that a geometrically already existing slip angle between the wheel plane and the instantaneous direction of travel is maintained and not eliminated again by placing the two jostling rollers 47 and 13 against the inside of the lateral-guidance runner 28 with a direction of travel 41' and placing the jostling roller 47 against the lateral-guidance runner 28, the further jostling roller 47 is mounted with a slight offset - corresponding to the slip angle mentionedtowards the outside compared with the jostling position of the lateral-guidance roller 13. In this manner, the lateral force can be partially transferred via the tyre contact area and partially via the two jostling rollers 47 and 13 and the corresponding holding arms 48 and 14. In this arrangement, the load of lateral forces is almost completely removed from the steering linkage.

P 1 1.

23

Claims

1. A track-guidable, bidirectional articulated vehicle, which vehicle has vehicle sections, vehicle joints and vehicle axles which, seen transversely to the direction of travel are centre-symmetrically constructed or arranged, which vehicle or bus furthermore exhibits one fully equipped driver's cabin each at both vehicle ends and is optionally fully operational in one or in the other direction of travel, all vehicle axles furthermore being equipped with lockable wheels, the vehicle axles located nearest. to the vehicle ends - outer axles - being constructed as driving axles, furthermore with lateralguidance rollers which are arranged close to the ground in the wheel area and interact with track- determining lateral-guidance runners along the roadway, which are held in unchangeable lateral position with respect to the wheel plane of the respective lockable vehicle wheels via wheelencircling holding arms and which laterally project outwards past the vehicle wheels, wherein a) the articulated vehicle is constructed in two sections having only one centrally arranged vehicle joint and three vehicle axles; only the two outer axles are provided with lateral guidance rollers, lateral-guidance rollers also on the in each being arranged only on circumferential side of te c) d) e) one side vehicle wheels case pointing towards the vehicle end; each of the outer axles, can also be manually steered from the driver's cabin but in each case only the one, which is in each case the nearest; all vehicle axles are constructed in such a manner that the respective lockable vehicle wheels can be locked in the straight-ahead position; the centre vehicle axle is approximately coincident with the vehicle joint and - in deviation from the centre-symmetrical overall vehicle construction is 24 pivoted at one of the two vehicle sections - twoaxle vehicle section - in a manner known per se nonrotatably, seen in plan view, the other vehicle section defining a single-axle vehicle section; when its looking in the straight-ahead position is cancelled, the centre vehicle axle can be independently steered in dependence on the bending angle between the two-axle and the single-axle vehicle section in such a manner that the lockable vehicle wheels of the centre vehicle axle are always aligned in parallel with the single-axle vehicle section; control measures which automatically become effective after the selection of the direction of travel ensure that the outer axle which is in each case at the front in the selected direction of travel is enabled to be steerable and that, at the same time, the vehicle wheels of the outer axle which is in each case at the rear in the selected direction of travel is locked in the straight-ahead position; further control measures which also automatically become effective after the selection of the direction of travel also ensure that when the direction of travel is selected to be in the direction of the two-axle vehicle section, the vehicle wheels of the centre vehicle axle are locked in the straightahead position and that, in contrast, when the direction of travel is selected to be in the direction of the single-axle vehicle section, automatic steerability of the centre vehicle axle is established and enabled.

f) g) h)

2. An articulated vehicle according to Claim 1, wherein the centre vehicle axle is provided with rotatable steering knuckles which carry the vehicle wheels and which in each case carry a track lever which approximately extends in the longitudinal direction of the vehicle and the free ends of which are pivotably connected by a track 1 rod which is located in parallel with the vehicle axle, the axes of rotation of the steering knuckles and the joints between the track levers and the track rod being located at the corner points of a rectangle in the straight-ahead position of the vehicle wheels.

3. An articulated vehicle according to Claim 1 or 2, wherein the toe-in of the vehicle wheels of at least the centre vehicle axle is zero degrees.

4. An articulated vehicle according to Claim 1, 2 or 3, wherein, apart from the - first - lateral-guidance rollers mentioned, which are held by the holding-arms, at least at the two holding arms in each case located on the vehicle side facing away from the driver's station, in each case a further lateral-guidance roller is movably held in such a manner that each of these further lateral-guidance rollers, independently of the first lateral-guidance roller.

in each case associated can be lowered into a lowered working position (continuous lines in Figure 3) which is at approximately the same level as the associated first lateral-guidance roller, is in approximately the same position in the longitudinal direction and is outside it in the width direction and -seen in the longitudinal direction - exhibits a clear distance (a) from its circumference, or can be raised into a raised rest position (dot-dashed in Figure 3) which projects over the lateralguidance runner along the roadway.

5. An articulated vehicle according to Claim 4, wherein the further lateral-guidance roller is supported on a rotating lever which is rotatably pivoted at the holding arm.

6. An articulated vehicle according to Claim 4 or 5, wherein control measures which automatically become effective after the selection of the direction of travel ensure that the adjustability of the further lateral4 26 guidance roller is also enabled only when the steerability of the outer axle located at the front in the selected direction of travel is enabled and that, at the same time, the further lateral-guidance roller is moved into the raised rest position and is blocked therein in the case of the outer axle which is at the rear in the selected direction of travel and is blocked in the straight-ahead position.

7. An articulated vehicle according to Claim 6, wherein the further lateral-guidance roller, the adjustability of which is enabled, is functionally locked in the end position which happens to exist in each case, that is to say in the lowered operating position or in the raised rest position, due to control measures, and that this functional locking can only be cancelled when the vehicle speed of the articulated vehicle is below a particular threshold value or if the lateral force of the associated first lateral-guidance roller or of the corresponding holding arm is above a particular threshold value.

8. An articulated vehicle according to any one of Claims 1 to 7, wherein each of the first lateral-guidance rollers is mounted movably at the holding arm carrying it, in such a manner that the lateral-guidance roller can be optionally raised into a rest position passing over the top edge of the lateral-guidance runners along the roadway or can be lowered into an operating position which is located below the top edge of the runner and that control measures which automatically become effective after the selection of the direction of travel ensure that - at least in track-bound vehicle operation - in the case of the outer axle which is at the front in the selected direction of travel and the steerability of which has been enabled, the two associated first lateral-guidance rollers are lowered into the operating position and, at the same time, at the outer axle which is selected direction of travel and which at the rear in the is '..locked in the 0 1 27 straight-ahead position, the two associated first lateralguidance rollers are raised into the rest position.

9. An articulated vehicle according to any one of Claims 1 to 7, wherein each of the first lateral-guidance rollers is mounted movably at the holding arm carrying it, in such a manner that the lateral-guidance roller can be optionally adjusted into an operating position which projects by about half the diameter of the first lateralguidance roller past the outside tyre side wall of the respective associated vehicle wheel or into a jostling position which is at the same level, retracted but still projecting past the outside tyre side wall by at least one centimetre and that control measures which automatically become effective after the selection of the direction of travel ensure that - at least in track-bound vehicle operation -the two associated first lateral-guidance rollers at the outer axle which is located at the front in the selected direction of travel and the steerability of which has been enabled, are moved out into the operating position and, at the same time, at the outer axis the two associated first lateral-guidance rollers located at the rear in the selected direction of travel and blocked in the straight- ahead position are retracted into the jostling position.

10. A track-guidable, bidirectional articulated vehicle, substantially as described herein, with reference to, and as illustrated in the accompanying drawings.

1>ublished1990ar,ie Patent Office. State House. 66 71 High Hc.jorr,. LcndonWC,:-',4'rP Further copies maybe obtamedfroln The Palenloffice