Abstract:
A wheeled carriage is capable of moving on rails to-and-fro, and of moving on a railless flat floor in any desired direction. The carriage has at least three pivotable wheel units. Each of these units consists of a first wheel and a second wheel. The first wheel includes a core wheel portion and a raised peripheral wheel portion surrounding the latter. The second wheel resembles substantially the core wheel portion of the first wheel. The wheel unit is designed for making two contact points with rails when seen in side view and equally making two contact points with rails when seen in its front or rear view.

Description:
CROSS-REFERENCE OF RELATED APPLICATION 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 311,020, filed Oct. 13, 1981, now U.S. Pat. No. 4,494,464. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to improvements in and relating to wheeled carriages. More specifically, it relates to novel semi-bogie-type wheel units carrying the carriage. 
     In the prior art, such a carriage is already known which is provided with several non-bogied pairs of metal wheels, each comprising tapered side portions adapted for establishing rolling point contact with inside upper edge corners of a pair of specifically designed rails having a rectangular or inverted channel cross-section, a flat central portion being however provided between the both tapered side portions and fitted rigidly with a raised solid rubber ring tire, so as to be rollable on a flat railless floor. Although it is convenient to support each wheel of the two wheel units of front, intermediate and rear wheel units by a separate and independent axle. However, if desired, each lateral two pairs of the wheel units may be supported by a single and common axle. It should be noted that the term &#34;front&#34;, &#34;intermediate&#34; or &#34;rear&#34;  is used only for convenience of description, because the carriage is runnable to-and-fro on the rails as well as the railless floor. 
     This kind or carriage which has four contact point type wheel treads when seen in one lateral axle line, is usable for various purposes. As an example, a staged lecture hall can be utilized as a sports- or amusement one, when all the chairs and the like movable attributes have been carried into an idle space below the stage, so as to leave in the hall a broad unobstracted flat floor. 
     For this purpose, a number of parallel rail pairs are laid below the stage and the same number of the above kind of carriages are provided for carrying away the chairs and the like thereon and into the under-stage, otherwise idle space, together with the carriage. On the railless floor, these carriages run with the rubber tires. For reuse of the hall for lecture service, the carriages are manually drawn out together with the loaded chairs onto the railless floor, for unloading and resetting them on the floor again. These chairs are also of the collapsible type. 
     In this wheeled carriage, all the wheels are so-to-speak journalled, although normally antifriction bearings are provided between the wheel and its axle, and thus these wheels are not polstered or swivelled relative to the carriage proper. Therefore, the carriage can run only on a straight line. However, it would be highly convenient if the carriage can run laterally on the railless floor. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to realize such an improved carriage which can easily run laterally on the railless floor. 
     If such to-and-fro runnable carriage as above described be provided with polstered wheels, the return movement thereof on rails would be practically unable, because in this case the polstered wheels will be subject to a 180  deg.-turning movement and liable to disengage from the mating rails. 
     According to this invention, a semi-bogied twin wheel combination commonly pivoted to the bottom of the carrier is proposed for avoiding otherwise possible heavy friction loss with the cooperating rails and liable disengagement of the wheels from the latter to be encountered in the return running service. 
     This and further objects, features and advantages of the invention will become more apparent as the description goes on in connection with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an end view of a twin-wheel unit as seen from the right hand side thereof in FIG. 2. 
     FIG. 2 is a side view of the twin-wheel unit. 
     FIG. 3 is an end view of a modified embodiment partially sectioned. 
     FIG. 4 is a schematic plan view of a wheeled carriage, provided with four twin-wheel units. 
     FIG. 5 is a similar view to FIG. 1, showing a slightly modified wheel-rail combination, and 
     FIG. 6 is a substantial horizontal section of a still further modified twin-wheel unit. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the first embodiment in the drawings, FIGS. 1-4 and a slight modification in FIG. 5, the invention will be described in detail. 
     In these drawings, numeral 1 represents only a part of a wheeled vehicle, chassis or carriage, having a pivotable support 2 which is pivotally mounted on the vehicle at 9. This support 2 has twin arms 2a and 2b when seen at its side view shown in FIG. 2, carrying rotatably a first wheel 3 and a second wheel 4 supported for this purpose by respective wheel shafts 3a and 4a, respectively. Between these shafts and respective wheels, there are provided naturally bearing means, preferably of the antification type, as at 5 in FIG. 3. 
     The first wheel 3 comprises a solid main or core wheel portion 3b, made of steel or the like rigid material, an elastic ring wheel portion 3c, preferably made of natural or synthetic rubber, being fixedly and centrally attached around the periphery of the core wheel portion by the conventional baking, vulcanizing, cementing or adhering technique. 
     The core wheel portion comprises two cup-shaped halves which are joined together by welding. Numeral 6 shows such seam or welded line. However, if necessary, the core wheel may be of the solid and rigid one piece structure made of cast iron, cast steel, forge steel or the like. 
     The outline configuration of core wheel 3b represents a central flat C and side tapers A and B. The ring wheel 3c is mounted on the central flat as shown. 
     If necessary, however, the ring wheel portion is made of iron or steel and integral with the core wheel. 
     As may be well supposed, the second wheel 4 has substantially same outline and structure with those of said core wheel 3b. In this case, the outer ring wheel portion has been dispensed with. The central flat as shown with C&#39; while the side tapers are represented with A&#39; and B&#39;. 
     Numerals 7 and 8 represent a pair of parallel rails of a specific design. In the embodiment shown, the rail has a hollow rectangular cross-section. If necessary, however, the rail may be rigid instead of hollow. Further, it may be of the channel section opening towards upper. 
     As shown schematically in FIG. 4, one carriage 1 is provided wth two front and two rear twin-wheel units W1; W2; W3 abd W4. The front wheel units W1 and W2 are arranged along lateral imaginary line 100. In the similar way, the rear wheel units W3 and W4 are arranged along lateral imaginary line 101. Naturally, these two lines 100 and 101 are parallel with each other. Each wheel unit comprises the first wheel 3 and the second wheel 4. When seen, however, in the lengthwise direction of the carriage 1, the first wheel is situated always in the outer position relative to the second wheel. 
     As seen from the drawings, each of the wheel units, W1, W2, W3 and W4, shows two contact points with the rails. Thus, when seen along the lateral line 100 or 101, there are four contact points between the wheels and the rails. Naturally, there are four rails per carriage. It should be noted, however, the term &#34;contact point&#34; is used only in the theoretical meaning. However, in practice, these point contacts are realized as far as possible. This wheel-rail relationship is naturally far remote from the conventional traffic one in which the contact is of the line contact mode in contrast to the point contacts adopted in the present invention. By the adoption of this four-point contact principle in line, the desired optimal automatic self-centering function for the wheels can be positively assured when the carriage runs on the double twin-rail arrangement as shown in FIG. 4. 
     In the modified embodiment shown, the upper end 2a of wheel supprt 2 is rotatably supporting the carriage 1 by means of two mutually overlapped swivel or thrust bearings 10; 11 for the same swivelling purpose as at 9 in FIGS. 1 and 2. 
     Although in FIG. 2, the wheel support 2 is shown in the downwardly opening, two arm style, but this specific configuration is not limitative. The support 2 may have any other suitable side configuration such as a rectangular plate, channel yoke, or trapezoidal box or channel shape, if necessary. 
     The raised thickness dimension, t, of outer central elastic or rigid wheel portion 3c is so selected that when the carriage run on the railless flat floor D, the second wheel 4 does not touch and thereby avoids contacting the floor surface. On the contrary, when the carriage runs on the rails, the first and second wheels will contact the rail edges. As shown in FIG. 2, the outer ring wheel portion 3c is kept separated completely from the rail edges, as may be most clearly seen from FIG. 3. 
     By virtue of the twin wheel contact with each rail when seen at the side view of the twin wheel unit W1, W2, W3 or W4 as is the case of FIG. 2 where the carriage travels on rails, each of the wheel units can not execute practically any swivel movement relative to the rails. 
     On the contrary, when the carriage is pushed forward or drawn rearward, and its first wheels only serve for running by means of the centrally raised outer ring portion 3c, the wheel units W1, W2, W3 and W4 can swivel substantially simultaneously to any desired direction by receiving occasional and specific manual physical effort by the operator other than direct forward or rearward direction. It may therefore be supposed that the carriage can run on the flat floor D in any desired direction as occasion may desire. Thus, it can move even in the quite lateral direction. 
     In a modified arrangement, although not shown, the carriage may have two front wheel units W1 and W2 and only one wheel unit such as W3 as the rear side supporting wheel means. In this modification, and if desired, the single wheel unit may be of non-pivotable type. 
     As for the one wheel unit or rails, the contact points are four in total with the rails. On the contrary, each wheel unit will establish only one contact line with the flat floor when the carriage runs on the railless flat floor. 
     If one wheel unit is used in place of the two wheel units, a pair of auxiliary rails must naturally be provided centrally between the existing two sets of rails and in parallel thereto. 
     If necessary, the second wheel may consist of a ball type wheel. 
     It should be noted that the term taper in this specification may consist of a convexedly curved surface. 
     In FIG. 5, a slight modification from the first embodiment is shown. In this modification, the rails 7&#39; and 8&#39; are formed with centrally directing, downward inclined taper surfaces 7&#39;a and 7&#39;b so as to mate with the corresponding wheel taper surfaces A&#39; and B&#39; for establishing, two-line contact with the rails 7&#39; and 8&#39;, in place of the four point contact as was adopted in the first embodiment. By adopting this modified wheel-rail contact, rail wear can be reduced than otherwise. Although not shown, the core wheel 3, FIG. 3, may establish a line-contact effect with these modified rails 7&#39; and 8&#39;. For clear understanding without further comments, similar other reference numerals to those adopted in FIG. 1 have been employed herein. 
     In the still further improved modification of the first embodiment is shown schematically at FIG. 6. In this modification, the second or auxiliary wheel 4 is formed with a ring recess 12 which embraces the said elastic ring wheel portion 3c with ample idle gaps. By adopting such a partially overlapping wheel arrangement, the axial length L can be reduced considerably than otherwise. The increased taper of the wheel taper surfaces for wheel 4 compared to wheel 3, as shown in FIG. 6, establishes two line contact for wheel 3 and two point contact for wheel 4 when used with rail 7&#39;, 8&#39; shown in FIG. 5. 
     Additionally, a pair of ball bearings 5&#39; are shown for clearly demonstrating the rotatable mounting of the second wheel 4 on the axle 3b.