GB2313818A

GB2313818A - Article transporting vehicle and guiding system therefor

Info

Publication number: GB2313818A
Application number: GB9710920A
Authority: GB
Inventors: Hiraoki Kita; Haruhiro Watanabe
Original assignee: Daifuku Co Ltd
Current assignee: Daifuku Co Ltd
Priority date: 1996-05-29
Filing date: 1997-05-28
Publication date: 1997-12-10
Anticipated expiration: 2017-05-28
Also published as: FR2749251A1; GB9710920D0; FR2749251B1; DE19722108B4; KR970074604A; JPH09315296A; DE19722108A1; GB2313818B; KR100342266B1

Description

2313818 ARTICLE TRANSPORTING VEHICLE AND GUIDING SYSTEM THEREFOR The

present invention relates to an article transporting vehicle guided along a guide rail and a system for guiding the vehicle along the rail.

An article transporting vehicle and its guiding system are for use in an automated warehouse, various factories or the like. As the article transporting vehicle, in addition to the above-noted rail-guided type. other types are also known such as a magnetically guided article transporting vehicle which is guided by means of e.g. a magnetic tape, and conventional fork-lift trucks.

Each type has its own merits and demerits. For instance, the vehicle guided along a guide rail provides greater running stability than the other types.

With this stability, the traveling speed of the vehicle may be increased to improve the operational efficiency. This is not possible or at least difficult with the other types of vehicles.

On the other hand, the demerit of the rail-guided type vehicle is the requirement of the guide rail which is to be installed on a traveling surface of the vehicle. Indeed, this requirement of installing the guide rail on the traveling surface has been major cause of restriction in the field and range of application of this type of transporting system.

The guide rail may be embedded under the traveling surface. However, 2 this requires a large-scale rail set-up operation. For this reason, in manly actual installations, the guide rail is installed simply on the traveling surface. However, the presence of the guide rail installed on the surface necessarily interferes with other works. Especially, in the case of the conventional construction of this type, the guide rail is installed in such a manner that the entire rail projects laterally, i.e. in a plan view. from an article transfer section. Then, the presence of the laterally projecting guide rail would present an obstacle not only when a trouble-shooting becomes necessary for a trouble occurred in the vehicle guided along the guide rail obviously and but also when it is desired to transfer an article to or from the article transfer section by using also a non-rail guided vehicle such as a conventional fork-lift truck in addition to the rail-guided vehicle. That is, the laterally projecting guide rail denies easy access of e.,a,.

the fork-lift truck to the article transfer section needed for the article transfer.

The present invention addresses the above-discussed problems of the is prior art, and a primary object of the invention is to provide an article transporting vehicle and its guiding system which fully maintain the above-described advantage of the rail-guided type vehicle and system while allowing easy access of other non-rail-guided vehicle such as a fork-lift truck to the article transfer section, so that the field and range of application of this type of vehicle and its guiding system may be significantly expanded.

For accomplishing the above-noted object, an article transporting vehicle and a guiding system therefor, comprises:

a self-propelled vehicle traveling along a traveling path, the vehicle having a guide portion; a guide rail for contacting the guide portion for guiding the vehicle; an article transfer section disposed along the traveling path, the transfer 3 section having a transfer platform for transferring an article to and from the transport vehicle; wherein, in the article transfer section, the guide rail is disposed beneath the &=fer platform.

The above-described construction allows any other non-rail-guided article transporting vehicle such as a fork-lift truck to make an un-obstructed access to the article transfer platform of the article er section to smoothly er an article between the vehicle and this article transfer section.

Accordingly, the article transfer section which could be used only by the article transporting vehicle guided along the guide rail in the case of the conventional construction, has been made available also by any other non- rail guided transporting vehicle such as a fork-lift truck, a m agnetically guided article transporting vehicle or the like. Then, the invention has fully achieved its intended primary object of providing an article transporting vehicle and its guiding system which fully maintain the advantage of the raff-guided type vehicle and rail-guiding system while allowing un-obstructed access by a non rail-guided vehicle such as a fork-lift truck to the article transfer section, so that the field and range of application of this type of vehicle and its guiding system may be significantly expanded.

According to a further aspect of the present invention, the guide rail includes a power supply rail for supplying power to the article transporting vehicle.

With this, it becomes possible for the vehicle to obtain power from the system.

Therefore, it becomes unnece to provide the vehicle with its own power source such as a battery or to provide a charging unit therefor. Then, the vehicle can travel continuously for a long period of time. Preferably, the power supply rail is disposed underneath the article transfer platform. Then, the power supply rail too does not present any obstacle to the other article transporting vehicle such as a fork-lift truck, so that the article may be smoothly transferred to and from the article transfer section by using such non- rail-guided 4 vehicle as described above.

Preferably, the guide rail includes a curved rail portion. This allows greater freedom in designing the traveling path of the vehicle, in comparison with a case where the guide rail is constructed solely from a straight rail portion. Still preferably, the article transporting vehicle travels on the outer side of the curved rail portion and the article er section is disposed on the inner side of the curved rail portion. With this, it is possible to reduce the length of the entire guide rail for providing a certain fixed distance of the vehicle traveling path as well as the area needed for installing the guide raiL Accordingly, this construction provides economic advantage.

The reverse arrangement is also possible, in which the article transporting vehicle travels on the inner side of the curved guide rail portion and the article transfer section is installed on the outer side of the curved rail portion. In this case, the length and installment area of the guide rail are somewhat increased is in comparison with the above-described arrangement. However, as the radius of the curved rail portion is increased, the vehicle may travel at this portion more smoothly. Then, as the vehicle can comfortably travel at this portion at a relatively high speed, the operation efficiency may be further improved.

Preferably, the guide rail is provided in the form of a loop. With this, the vehicle may travel unidirectionally along the rail, without having to switch over the direction back and forth. Then, by causing a plurality of article transporting vehicles to travel at one time along the guide rail in the form of loop, the operational efficiency of the entire system may be further improved.

In the above construction, if the vehicle(s) is caused to travel on the inner side of the loop-like guide rail, the vehicle(s) may travel smoothly at a high speed. More preferably, a portion of the loop-like guide rail is detachable from the rest of the rail. With this, by detaching this portion, other non- rail-guided article transporting vehicle such as a fork-lift truck may travel into the inside of the loop through the portion thereof opened by the detachment of the detachable rail portion. Thus, the article transfer operation between this vehicle and the article trdnsfer section may be effected without any trouble.

According to a still further aspect of the invention, the article Uer section includes a fer conveyer. In this case, this article transfer section may be used for transferring an article to and from a storage shelf of an automated warehouse, and the article transfer vehicle too may be used in such automated warehouse. In such automated warehouse, a conveyer is provided for carrying articles in and out of the warehouse. In the case of the convention, this conveyer can be used solely by the article transporting vehicle guided along a guide rail. Then, with the above-described construction, this conveyer can now be utilized also by any other type of article transporting vehicle such as the magnetically guided type or the fork-lift truck. Consequently, the above construction significantly increases the convenience and usefulness of such automated warehouse.

is According to a preferred embodiment of the invention, the article u=porting vehicle includes a non-steering drive wheel and a non-steering driven wheel, and the guide portion of the vehicle includes first and second guides which are disposed with a distance therebetween in the fore-and-aft direction of the vehicle, the drive wheel being disposed substantially at the fore-and-aft center between the first and second guides and on a virtual line extending in a transverse direction normal to the fore-and-aft direction of the vehicle. With this construction, the distance from the first guide to the drive wheel and the distance from the second guide to the drive wheel are equal to each other, so that an angular moment resulting from a reaction force developed in the first guide is offset by an angular moment resulting from a reaction force developed in the second guide. As a result, it becomes possible to restrict pressing force applied to against the fiat guide due to the reaction force, thereby restricting occurrence of distortion between the first and second guides and the guide rail, and the vehicle may be smoothly driven by using the rotational force of the drive 6 wheels efficiently. Further, as the drive wheel and the driven wheel are provided as non-steering wheels, the entire construction may be formed simple, not needing a steering mechanism.

Preferably, the guide portion is caused to project laterally outwards from the vehicle. Then, even if the guide rail is disposed adjacent a wal the vehicle may smoothly travel with its guide portion being guided along the guide raiL.

As a result, when the traveling path is used by any other non-rail-guided vehicle than the transporting vehicle, the guide rail hardly interferes with the traveling of such other vehicle.

Preferably, the drive wheel is disposed with an offset toward the guide portion from a width-wise center of the vehicle in the transverse direction.

With this, the drive wheel may be disposed as closely as possible to the guide portion. As a result, even if there occurs distortion between the guide portion and the guide rail when the vehicle pivots about the guide portion due to the chive force from the chive wheel, the amount of such distortion may be minimized because of the short distance between the drive wheel and the guide portion.

Hence, the guide portion may move further smoothly along the guide rail Preferably, the vehicle includes one drive wheel and two driven wheels.

With this, the drive wheel and both of the driven wheels may reliably keep contact with the floor surface when this surface has some unevenness. Then, the vehicle may travel in a stable and reliable manner, in spite of such unevenness in the floor surface.

In case the transporting vehicle travels on the inner side of the curved portion, it is preferred the disposing position of the drive wheel and the curvature of the curved portion of the guide rail are correlated to each other in such a manner that the drive wheel may be located between a center of the curved rail portion and the curved guide rail portion. With this, when the drive wheel travels on the inner side of the curved portion of the guide rail, the drive wheel may reliably provide its drive force so as to smoothly propel the vehicle.

7 Preferably, each of the first and second guides includes a pair of guide rollers provided on one side of the guide rail with a distance therebetween mi the fore-and-aft direction and a further pair of guide rofiers provided on the other side of the guide rail with a distance therebetween in the fore-and-aft direction.

With this, where the guide rail is curved, at least one guide roller on the right or left side provides its guiding effect Hence, it is possible to restrict occurren,5e of trouble of the guide roller entirely detaching from the right or left side.

Consequently, the transporting vehicle may be reliably and precisely steered along the guide rail whether the guide Mil is curved or not.

Advantageously, the article transporting vehicle further comprises a roller support member for supporting each of the guide rollers to be rotatable via a vertical axis. With this, where the guide rail is curved, the roller support is pivoted to allow two guide rollers to provide their guiding effect on both the right and left sides. 'Mus, the transporting vehicle may be reliably and precisely is steered along the guide rails whether the guide rails am curved or not The invention will now be described by 4ay of example, with reference to the accompanying drawings, in which:

Fig. 1 is a plan view showing an automated warehouse using an article transporting vehicle and a guiding system therefor relating to one preferred embodiment of the present invention, Fig. 2 is a plan view showing principal portions of the article transporting vehicle and the guide system of the present invention, Fig. 3 is a front view of the portions shown in Fig. 2, Fig. 4 is a plan view showing an article transporting vehicle and a guide system relating to a further embodiment of the present invention, 8 Fig. 5 is a plan view showing an article transporting vehicle and a guide system relating to a still further embodiment of the present invention, Fig. 6 is a plan view showing an article transporting vehicle and a guide system relating to a still further embodiment of the present invention, Fig. 7 is a section view showing a guide rail and a guide member according to a further embodiment of the present invention, and Fig. 8 is a descriptive view for illustrating forces applied to guide rollers due to a drive force from a drive wheel.

Referring now to the drawings, this article transporting is vehicle is for use.in e..g. an automated warehouse shown in Fig. 1. This automated warehouse includes storage shelves 1 for storing various articles A as mounted on respective pallets P. The storage shelves 1 are provided in a plurality of groups each of which consists of an opposed pair. And, in the particular construction shown in Fig. 1, two groups 20 of storage shelves 1 are provided.

Between each opposed pair of storage shelves 1, a stacker crane 2 equipped with a vertically movable lift table, fork or the like is provided to be movable along a rail 3. In operation, the stacker crane 2 carries the article A as mounted on the pallet P which in turn is mounted on a carry-in lifter 4 from this lifter 4 25 into one of the storage sections of the storage shelf 1 or carries out the article A in the storage section on to a carry-out lifter 5.

Forwardly of the carry-in lifter 4, there is provided a carry-in transfer lifter 6 constituting an article transfer section. Also, forwardly of the cany-out lifter 5, there is provided a carry-out transfer lifter 7 constituting another article 9 transfer section. Between the carry-in transfer lifter 6 and the carry-in lifter 4, there is provided a carry-in chain conveyer 8 for conveying the article A on the pallet P mounted on the transfer lifter 6 to the carry-in lifter 4. Similarly, between the carry-out transfer lifter 7 and the carry-out lifter 5, there is provided a carry-out chain conveyer 9 for conveying the article A on the pallet P mounted on the carry-out lifter 5 to the fer lifter 7.

More particularly, the carry-in lifter 4 and the carry-in transfer lifter 6 are disposed on the inner side of the carry-in conveyer 8, thus constituting portions of this carry-in conveyer 8. Similarly, the cany-out lifter 5 and the carry-out transfer lifter 7 are disposed on the inner side of the carry-out conveyer 9, thus constituting portions of this carry-out conveyer 9.

Between the each carry-in lifter 6 and the corresponding carry-out lifter 7, a self-propelled article transporting vehicle 10 m(;unting expandable forks 10a on a top surface thereof can travel on a floor face as a traveling surface, and along is this traveling path, there is installed a single rail 11 for guiding the article transporting vehicle 10 along it This single rail 11 is provided as a loop-like guide rail including two curved portions 11 a; and a plurality of article transporting vehicles 10 can simultaneously travel on the inner side of this loop-like guide rail 11.

On the outer side of the loop-like guide rail 11, there are provided article cany-in and carry-out sections 12, 13 as still further article transfer sections. In operation, each article transporting vehicle 10 can 'scoop up', by means of its fork 10a, the article A together with the pallet P and then transport them on to the carry-in transfer lifter 6 or conversely scoop up the article A together with the pallet P on the cany-out transfer lifter 7 to the article carry-out section 13.

The loop-like guide rail 11 has a pivotably fixed portion 1 lb. Then, by pivoting this portion 11 b away from the rest of the guide rail 11, a nonrail-guided article transporting vehicle such as a fork-lift truck 14 can travel into the inner area surrounded by the loop-like guide rail 11.

As shown in Fig. 3, the guide rail 11 has a side-syrnmetrical cross sectional shape defining a laterally V-shaped recess 15 in each of right and left faces thereof along the entire length of this rail 11. And, this guide rail 11 is supported via a plurality of leas 16 on the floor surface to be substantially parallel therewith.

Further, the guide rail 11 is disposed underneath a transfer platform B of each of the article er sections, i.e. the carry-in and carry-out transfer lifters 6, 7 and the article carry-in and carry-out sections 12, 13. To the legs 16 supporting the guide rail 11 and along this guide rail 10, there is attached a power supply rail 17 for supplying driving electric power to the article transporting vehicle 10. And, this power supply rail 17 too is disposed entirely underneath the transfer platfonn B of the respective article transfer sections.

Incidentally, at the pivotably fixed portion 1 lb of the guide rail 11, the power supply rail 17 too is adapted to be connectable and disconnectable by means of various connectors.

The article transporting vehicle 10 includes first guides 19A, 19B and second guides 19C, 19D which guides together constitute a'gtfide portion'. The first guides 19A, 19B and the second guides 19C, 19D are disposed with a distance therebetween in the fore-and-aft direction of the vehicle 10. More particularly, the first guides 19A, 19B comprise a pair of guide rollers 19A disposed on one side of the guide rail 11 with a distance therebetween in the fore-and-aft direction and another pair of guide rails 19B disposed on the other side of the guide rail 11 with a distance therebetween in the fore- and-aft direction. Similarly, the second guides 19C, 19D comprise a pair of guide rollers 19C disposed on the one side of the guide rail 11. with a distance therebetween in the fore-and-aft direction and another pair of guide rails 19D disposed on the other side of the guide rail 11 with a distance therebetween in the fore-and-aft direction. All of these guide rollers 19A, 19B and 19C, 19D are attached to respective roller support members 18 to be rotatable about respective vertical axes.

One of these roller support members 18 disposed one after the other in the fore-and-aft direction mounts a current collector 20 for coming into contact with the power supply rail 17, such that the driving electric power or current is supplied through the power supply rail 17 and the current collector 20 to the article transporting vehicle 10. Also, each entire roller support member 18 including all of its components, i.e. the collector 20 and the first or second guide rollers 19A, 19B, 19C, 19D is constructed so as to be disposed underneath the transfer platform B of the article transfer section such as the article cany-in transfer lifter 6.

The article transporting vehicle 10, as shown in Figs. 2 and 3, includes one drive wheel 25 driven by a motor M1 and total four driven wheels 26, 27. In Fig. 3, the driven whiels 27 are not shown for the sake of simplicity of the drawing.

Next, the disposing arrangement of the drive wheel 25 will be described. In this Fig. 8, a mark S1 denotes the first guide including the four guide rollers 19A, 19B and a further mark S2 denotes the second guide including the four guide rollers 19C, 19D, respectively. As shown, the drive wheel 25 is disposed on a virtual line KI, which extends substantially across the fore-and-aft center in a transverse direction normal to the fore-aft direction. With this, a distance L1 from the first guide S l to the drive wheel 25 and a distance L2. between the second guide S2 to the drive wheel 25 are rendered equal to each other. With this, an angular moment resulting from a reaction force R developed in the first guide S1 and an angular moment resulting from a reaction force R developed in the second guide S2 are completely offset with each other. Consequently, with the above-described disposing arrangement of the drive wheel 25, it is possible to prevent the first guide S1 from being pressed by the reaction force R, thereby to restrict occurrence of distortion which would otherwise occur among the first and second guides S 1, S2 and the cuide rail 11. As a result, the 12 vehicle may be propelled smoothly by efficiently utilizing the rotational force of the drive wheel 25 for the propellant of the vehicle.

In Fig. 8, a mark 112 F denotes a force component applied to each of the first and second guides S1, S2 by the driving force F from the drive wheel 25, and a mark F1 denotes a component force thereof tangent to the traveling direction of the first or second guide S 1, S2, i.e. tangent to the guide rail 11 and a mark. FZ denotes a component force thereof normal to the tangential component force Fl, respectively.

Further, the disposing position of the drive wheel 25 relative to the transverse direction of the transporting vehicle 10 is offset from the transverse, i.e. width-wise center of the vehicle toward the guides. Still further, the disposing position of the drive wheel 25 and the curvature of the curved portion 1 la of the guide rail 11 are correlated to each other in such a manner that the drive wheel 25 may be located between a center Q of the curved rail portion and the is curved guide rail portion 11 a.

As shown in Fig. 2, of the two pairs of driven wheels 26 and 27, the one pair of driven wheels 26 disposed on the opposite side of the vehicle relative to the drive wheel 25 and with the distance in the fore-and-aft direction are fixed in their direction relative to the vehicle body.

Whereas, the other pair of driven wheels 27 are pivotable about respective unillustrated vertical axes so as to change their directions relative to the vehicle body.

[other embodiments] Next, other embodiments of the invention will be specifically described.

In the following description of further embodiments, focus will be given on those portions distinct from the foregoing embodiment- It is understood however that one skilled in the art can readily combine all these features in various ways

13 with each other as long as such combinations result in any contradictions and that all these features are encompassed within the scope of the present invention.

In the foregoing embodiment, the guide rail 11 is provided in the form of a loop. 7he specific arrangement of this guide rail 11 may be modified in a variety of manners, depending on e.g. the requirements or conditions of its installation site.

For instance, as shown in Fig. 4, the guide ran 11 may be in the form of a straight rail, with the article carry-in and carry-out sections 12 and 13 being disposed on opposed sides on the straight rail across the carry-in and carry-out lifters 6, 7. In this case, the article transporting vehicle 10 travels back and forth along this straight guide rail 11.

For further instance, as shown in Fig. 5, the guide rail 11 may be composed of a single straight guide rail portion 11 and a single curved portion 1 la, with the article transporting vehicle 10 traveling on the outer side of the curved is guide rail portion 11 a and the article carry-in section 12 and carry- out section 13 as the article transfer sections being disposed on the inner side of the curved guide rail portion 11 a.

Further, in the above-described type of guide rail arrangement comprising the single straight portion and single curved portion, the vehicle 10 may alternatively travel back and forth on the inner side of the curved guide rail portion 11 a. In this case, all of the article transfer sections, i.e. the carry-in and carry-out transfer lifters 6, 7 and article carry-in and carry-out sections 12, 13 will be disposed on the outer side of the curved guide rail portion 11 a.

Fig. 6 shows a still further construction, in which the guide rail 11 is provided again in the form of loop, but the vehicle 10 is caused to travel on the outer side of the loop-like rail 11. In this case, the article carry-in and carry-out sections 12, 13 as the article transfer sections are disposed on the inner side of the loop-like guide rail 11.

In the foregoing embodiments, one guide rail 11 is provided. Instead, the 14 Present invention may be embodied in a system using more than two auide rails In the foregoing embodiment, at each article transfer section 6, 7, 12, 13, the guide rail 11 is entirely disposed underneath the transfer platform B. However, a portion of the guide rail 11 may project laterally from the transfer platform B of the respective transfer sections 6, 7, 12, 13 as long as this projecting rail portion does not present any obstacle to the other non-rail-guided vehicle such as the fork-lift truck 14. The same applies to the power supply rail 17. It is not absolutely necessary for this power supply rail 17 to be entirely disposed underneath the transfer platform B. Further, in the foregoing embodiment the pair of roller support members 18 are fixed to the vehicle body. Instead, as shown in Fig. 7, these support members 18 may be adapted to be pivotable about an axis 30, so that each member 18 may be movable between a condition where its guide rollers contact the guide rail 11' and a further condition where the rollers do not contact the rail 1V. During an article transporting operation, the roller support member 18 is placed under the former condition for keeping the guide rollers in contact with the rail 11' and f ixed in this condition to the vehicle body by means of bolts 3 1.

For dismounting the vehicle 10 from the guide rail 11, the bolts 31 are removed to allow the support members 18 to pivot about the respective axes 30 as shown by broken lines in Fig. 7, thereby to remove the guide rollers away from the guide rail 1 V. In this alternate construction, the guide rail 11' has a rectangular cross sectional shape so as to facilitate the removal of the guide rollers from this rail 1 V. In addition, the member supporting the guide rollers is pivotable about a vertical axis P1 via a ball bearing mechanism. Therefore, each guide roller is rotatable about respective axes as well as about the axis P1.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive. the 1 scope of the invention being indicated by the appended claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

16

Claims

1. An article transporting vehicle and a guiding system therefor, comprising: a self-propelled vehicle traveling along a traveling path, the vehicle having a 5 guide portion; a guide rail for contacdjg the guide portion for guiding the vehicle; an article transfer section disposed along the traveling path, the tramfer section having a transfer platform for transferring an article to and from the transport vehicle; wherein, in the article transfer section, the guide rail is disposed beneath the transfer platform.

2. A vehicle and system according to claim 1, wherein is the guide rail includes a power supply rail for supplying power to the article transporting vehicle, the guide rail being disposed underneath the article transfer I'D platform.

3. A vehicle and system according to claim 1 or 2, wherein the guide rail includes a curved rail portion, the article transporting vehicle travels on the outer side of the curved rail portion, and the article transfer section is disposed on the inner side of the curved rail portion.

4. A vehicle and system according to claim 1 or 2, wherein the guide rail includes a curved rail portion, the article transporting vehicle travels on the inner side of the curved auide rail portion and the article transfer c 17 section is installed on the outer side of the curved rail portion.

5. A vehicle and system according to claim 1 or 2, wherein the guide rail is provided in the form of a loop, the vehicle is caused to travel on the inner side of the loop-like guide rail. and a portion of the loop- like guide rail is detachable from the rest of the rail.

6. A vehicle and system according to any preceding claim, wherein the article transfer section includes a transfer conveyer.

7. A vehicle and system according to any preceding claim, wherein is the article transporting vehicle includes a non-steering drive wheel and a non-steering driven wheel, and the guide portion of the vehicle includes first and second guides which are disposed with a distance therebetween in the fore-and-aft direction of the vehicle, the drive wheel being disposed substantially at the fore-and-aft center between the first and second guides and on a virtual line extending in a transverse direction normal to the fore-and-aft direction of the vehicle.

8. A vehicle and system according to,any preceding claim, wherein the guide portion projects laterally outwards from the vehicle.

9. A vehicle and system according to claims 7 and 8, wherein the drive wheel is disposed with an offset toward the guide portion from a 0 18 width-wise center of the vehicle in the transverse direction.

10. A vehicle and system according to claim 7 or 9,- wherein the vehicle includes one said drive wheel and two said driven wheels.

11. A vehicle and system according to claim 7, wherein the guide rail includes a curved portion, the vehicle travels on the inner side of the curved portion, and the disposing position of the drive wheel and the curvature of the curved portion of the guide rail are correlated to each other in such a manner that the drive wheel may be located between a center of the curved rail portion and the curved guide rail portion.

is

12. A vehicle and system according to claim 7, wherein each of the first and second guides includes guide rollers disposed on the opposed sides across the guide rail.

13. A vehicle and system according to claim 7, wherein each of the first and second guides includes a pair of guide rollers provided 0 on one side of the guide rail with a distance therebetween in the fore- and-aft direction and a further pair of guide rollers provided on the other side of the guide rail with a distance therebetween in the fore-and-aft direction.

14. A vehicle and system according to claim 12 or 13, wherein the article transporting vehicle further comprises a roller support member for 19 supporting each of the guide rollers to be rotatable via a vertical axis.

15. A vehicle and system according to any preceding claim, wherein the guide portion is movable between a first position contacting the guide rail and a second position not contacting the guide rail.

16. An article transporting vehicle and guiding system therefor, substantially as herein described with reference to Figures 2, 3 and 8, in combination with any one of Figures 1 and 4 to 7 of the accompanying drawings.

is