Abstract:
A transport trolley for transporting goods and/or people, especially for transporting children. The trolley has a trolley frame including shoring elements and at least two wheeled devices provided on the frame and including wheels for rolling the transport trolley in a transport direction on a ground. One of the wheeled devices, as a front wheeled device in relation to the transport direction of the trolley, is arranged on the frame in front of the other rear wheeled device. The wheelbase between the front wheeled device and the rear wheeled device can be adjusted by means of an adjusting device on the trolley frame. Thereby, the wheelbase, i.e. the distance between a wheel of the front wheeled device and a wheel of the rear wheeled device, can be modified if necessary. When said transport trolley is pushed by a person, for example at a running pace, a longer wheelbase of the trolley is required for achieving the necessary tilting stability.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a National Phase Patent Application of International Application Number PCT/DE02/01275, filed on Apr. 2, 2002, which claims priority of German Patent Application Number 101 17 267.2, filed on Mar. 30, 2001. 
   FIELD OF THE INVENTION 
   The invention relates to a transport trolley for transporting goods and/or people, in particular for transporting children. 
   BACKGROUND 
   Patent specifications U.S. Pat. No. 2,976,912 and U.S. Pat. No. 6,017,051 each disclose strollers of a generic type of which the wheel base between the front and rear rolling devices can be adapted in accordance with existing ambient conditions. Patent specifications U.S. Pat. No. 3,937,485 and U.S. Pat. No. 4,659,096 describe corresponding transport trolleys for transporting goods. 
   These transport trolleys, however, are problematic when they are moved at relatively high speeds, as are reached, for example, during jogging or inline skating. If, in particular on an uneven underlying surface, they start to tilt and fall over, there is the risk of the person who is being transported being injured and/or of the article which is to be transported being damaged. 
   SUMMARY 
   The object of the invention is to provide a transport trolley of the generic type which, as far as possible, can be used universally and is suitable, in particular, for moving at relatively high speeds, as are reached when a person who is pushing the transport trolley is jogging. 
   According to the invention, it is provided that the trolley frame has two main struts which, starting from the region above each of the two rear rolling devices, are arranged such that they converge in an essentially V-shaped manner in the direction of the front rolling device, and the two main struts serve as a rollover bar in the event of the transport trolley tilting over. 
   By virtue of the V-shaped arrangement of the main struts, the structural dimensions of the transport trolley taper in the direction of the front rolling device, starting from the rear rolling devices. 
   The adjusting device of the trolley frame is preferably designed as at least one length-adjustable sliding strut of the trolley frame. It would likewise be conceivable, in principle, to have an adjusting device which makes it possible to adjust the wheel base between the front and the rear rolling devices by virtue of one or more frame elements being folded or pivoted. 
   In the case of a preferred embodiment, the sliding strut of the trolley frame, which is provided for adjusting the wheel base, extends essentially horizontally and is arranged in the region between the front rolling device and the rear rolling devices as strut elements of the trolley frame. With a suitable design of the rest of the strut elements of the trolley frame, and the connection thereof via articulation devices, it is thus possible for the wheel base of the transport trolley to be set quickly and straightforwardly by virtue of the sliding-strut length being changed. 
   The main struts are preferably designed such that they curve concavely upward, i.e. away from a rolling surface of the trolley. The trolley frame thus has enough installation space, in the region between the rolling surface of the trolley and the main struts, in order to accommodate the person who is to be transported and/or the article which is to be transported. 
   In a preferred embodiment, the trolley frame has in each case one supporting strut between the two end sections of the main struts which are arranged above the rear rolling devices and the rear rolling devices arranged therebeneath. Furthermore, a left-hand sliding strut is arranged between the left-hand main strut, as seen in the transporting direction, and the left-hand supporting strut and a right-hand sliding strut is arranged between the right-hand main strut and the right-hand supporting strut. At least one transverse strut is arranged between the two supporting struts. In this way, the individual elements (main, sliding, supporting and transverse struts) of the trolley frame define an essentially pyramid-like cage, of which the vertex or tapered end section is arranged in the region of the front rolling device. 
   The fastening of the supporting struts on the main struts, of the sliding struts on the main struts and of the sliding struts on the supporting struts is ensured via articulation devices. A suitable selection and arrangement of the articulation devices ensures that the trolley frame is of folding design, in order that the transport trolley can be collapsed in a space-saving manner if required. 
   In a further embodiment, the transport trolley has supporting struts which are of length-adjustable design. It is possible to reduce the height of the transport trolley by virtue of, for example, telescopic shortening of the supporting struts. 
   In order for it to be possible for the width of the transport trolley, i.e. the distance between the two rear rolling devices, to be reduced if required, transverse struts which have an arrestable folding articulation in their center are preferably provided, the end sections of the two main struts in the region of the front rolling device being articulated such that they can be moved in relation to one another. As an alternative, it would likewise be conceivable for the transverse struts to be of telescopic design in their lengthwise direction. 
   It is particularly advantageous, for this purpose, for the end sections of the two main struts in the region of the front rolling device to be coupled to one another by means of a universal joint. 
   A preferred embodiment of the transport trolley is characterized in that the sliding struts are fixed in a releasable manner on the supporting struts by means of an articulation device, which can be displaced along the associated supporting strut and can be fixed on the supporting strut. It is likewise advantageous if the supporting struts are fixed in a releasable manner on the main struts by means of an articulation device, which can be displaced along the associated main strut and can be fixed on the main strut. By virtue of the articulation devices which connect the sliding struts to the supporting struts being released, the articulation devices, and thus the end sections of the sliding struts, can be displaced upward along the supporting struts into the region of the rotary articulation between the supporting strut and main strut. In a second step, it is then possible for the rear rolling devices arranged on the supporting struts to be swung forward in the direction of the front rolling device. This makes it possible for the transport trolley to be collapsed quickly and straightforwardly in a space-saving manner. 
   The transport trolley preferably has a device for accommodating an article which is to be transported and/or a person who is to be transported, the accommodating device being fixed on the sliding struts and/or on the main struts. This accommodating device either is of foldable design, such that it can be collapsed together with the trolley frame, or it is fixed in a releasable manner on the trolley frame, with the result that it can be removed before the trolley frame is collapsed. 
   At least one of the rolling devices preferably has a spring-mounting arrangement. The spring-mounting arrangement serves, in particular when the transport trolley is advanced over uneven underlying surfaces, for absorbing the resulting vibration forces. For this purpose, the spring-mounting arrangement preferably has a spring excursion which is at least one fifth of the diameter of the wheel assigned to the rolling device. This has the advantage that the transport trolley can be moved over rough, i.e. uneven, terrain even at a running pace without the person who is to be transported and/or the article which is to be transported being subjected to intolerable vibrations. 
   A preferred embodiment of the transport trolley is characterized in that the main struts and/or the supporting struts, above the rear rolling devices, have at least one handle device for holding and steering the transport trolley. This handle device may be of height-adjustable design for adaptation to the height of a person who is moving the transport trolley. 
   A further preferred embodiment of the transport trolley is characterized in that at least one of the rolling devices has a braking arrangement for braking the rolling movement of the transport trolley, and in that the braking arrangement can be triggered by means of an actuating arrangement provided in the region of the handle device. Possible braking arrangements here are all customary and known braking arrangements such as rim brakes, drum brakes and disk brakes. For this purpose, it is advantageous if the connecting lines between the braking arrangement and the actuating arrangement provided in the region of the handle elements are arranged in the interior of the main and/or supporting tubes. 
   In order to secure the transport trolley, for example in a parked position, against rolling away in an undesirable manner, it is advantageous if the braking arrangement is designed such that it can be secured by means of the associated actuating arrangement. In addition, or as an alternative, it is possible to provide an additional latching arrangement in the region of a rolling device, the latching arrangement being actuatable when the transport trolley is at a standstill and preventing the wheels from rotating. 
   A further preferred embodiment of the transport trolley is characterized in that the front rolling device is mounted on the trolley frame such that it can be rotated about an essentially vertically arranged axis. Such a rotatably mounted front rolling device allows the transport trolley to be rotated over a small turning circle without much force having to be exerted. The front rolling device is preferably mounted such that it can be rotated over an angle range of less than 180°. Furthermore, the front rolling device includes a mechanical restoring device by means of which the at least one wheel assigned to the front rolling device, when pivoted out of a basic position in which it is oriented essentially parallel to the running direction of the wheels of the rear rolling devices, is subjected to a torque which directs it back into the basic position. 
   This achieves the situation where, in order to deflect the rotatably mounted wheel of the front rolling device, it is necessary to have a torque which has to be above the torque threshold predetermined by the restoring device. This property is important, in particular, for moving the transport trolley over rough terrain, in order that the torques produced by unevennesses of the underlying surface do not result in an undesired steering movement of the transport trolley which would have to be compensated for by a corresponding counter-steering action on the part of the person who is moving the trolley. 
   A further preferred embodiment of the transport trolley has coupling elements for coupling a wheelchair in the region of the supporting struts, in order that the transport trolley can be moved and steered by a person using a wheelchair. The transport trolley can thus be used for wheelchair users, in particular for the purpose of transporting additional articles. 
   A further preferred embodiment of the transport trolley is characterized in that the front rolling device is articulated on the trolley frame such that it can be pivoted upward and fixed in a pivoted position. Additional coupling means for coupling the transport trolley to a towing vehicle, in particular to a bicycle, can preferably be fastened on the trolley frame in the region of the front rolling device. The transport trolley can thus be used easily and straightforwardly as a bicycle trailer. It is possible here for the length of the bicycle trailer to be varied by the adjustable sliding struts of the trolley frame. 
   Moreover, the frame of the transport trolley can be collapsed to an even smaller packing size if the front rolling device is pivoted upward in the direction of the pyramid-like cage defined by the strut elements and is fixed on the trolley frame. 
   In addition, it is conceivable to use a suitable arrangement to increase the spacing between the rear rolling devices in order to increase the tilting stability of the transport trolley when used as a bicycle trailer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further aspects and advantages of the transport trolley according to the invention are explained hereinbelow with reference to the figures, in which: 
       FIG. 1  shows a perspective view of a first embodiment of the transport trolley; 
       FIG. 2  shows a perspective view of the transport trolley from  FIG. 1 , the wheel base having been shortened in comparison with  FIG. 1 ; 
       FIG. 3  shows a perspective view of the transport trolley from  FIG. 1 , the front rolling device having been pivoted upward and fixed on the trolley frame in order for the transport trolley to be utilized as a bicycle trailer; 
       FIG. 4  shows a perspective view of the transport trolley from  FIG. 1 , an arrangement for accommodating a person who is to be transported having been fitted on the trolley frame; 
       FIG. 5  shows a perspective view of the transport trolley from  FIG. 1 , an arrangement for accommodating an article which is to be transported having been fitted on the trolley frame; 
       FIG. 6   a  shows a perspective view of the transport trolley from  FIG. 1 , the two rear rolling devices having been brought closer together by virtue of the transverse struts being collapsed; 
       FIG. 6   b  shows a second embodiment of the transport trolley shown in  FIG. 6   a , this trolley having supporting struts which can have their length set telescopically; 
       FIG. 6   c  shows a view, in detail form, of the rear rolling devices with a further embodiment of the mechanism for folding the transverse struts; 
       FIG. 7   a  shows the transport trolley from  FIG. 6   a , the points at which the two sliding struts are articulated on the supporting struts having been displaced upward; 
       FIG. 7   b  shows the transport trolley from  FIG. 6   b , the supporting struts and the sliding struts having been shortened in length; 
       FIG. 8   a  shows the transport trolley from  FIG. 7   a , the rear rolling devices having been swung forward into the region of the front rolling device by virtue of the supporting struts being pivoted; 
       FIG. 8   b  shows the transport trolley from  FIG. 7   b , the rear rolling devices having been swung forward into the region of the front rolling device by virtue of the supporting struts being pivoted; 
       FIG. 9  shows a view, in detail form, of a rear rolling device with a spring arrangement and braking arrangement; and 
       FIG. 10  shows a view, in detail form, of a front rolling device which is arranged in a rotatable manner on the trolley frame and has a mechanical restoring device for the rolling device. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a perspective view of a first embodiment of the transport trolley. The transport trolley comprises a trolley frame  1  which is constructed from strut elements  10 ,  10 ′,  11 ,  11 ′,  12 ,  12 ′,  13 ,  13 ′,  133  and on which three rolling devices  2   a ,  2   b ,  2   b ′ are arranged. Each of the three rolling devices  2   a ,  2   b ,  2   b ′ has a wheel  20   a ,  20   b ,  20   b ′. By means of the wheels  20   a , 20   b ,  20   b ′, the transport trolley  1  can roll in a transporting direction T along an underlying surface. As seen in the transporting direction T, one of the rolling devices is arranged on the trolley frame  1  as front rolling device  2   a  and the other two rolling devices are arranged thereon as rear rolling devices  2   b ,  2   b ′. Each of the three rolling devices  2   a ,  2   b ,  2   b ′ has a spring-mounting device  21 , which is not illustrated in  FIG. 1  but is illustrated in detail in  FIG. 9 . 
   It is, of course, conceivable for a transport trolley according to the invention to have more than three rolling devices. Obviously, the rolling devices may be designed with more than one wheel, for example with twin tires. 
   The embodiment of the transport trolley which is illustrated in  FIG. 1 , on account of the triangular arrangement of the three rolling devices, constitutes merely a preferred, particularly compact embodiment of the transport trolley according to the invention. 
   Starting from the region above each of the two rolling devices  2   b ,  2   b ′, the trolley frame  1  has two main struts  10 ,  10 ′ which are arranged such that they converge in an essentially V-shaped manner in the direction of the front rolling device  2   a . In the region above the rear rolling devices  2   b ,  2   b ′, essentially vertically running supporting struts  12 ,  12 ′ are articulated on the main struts  10 ,  10 ′ via articulation devices  31 ,  31 ′. Starting from those end regions of the supporting struts  12 ,  12 ′ which are directed toward the rear rolling devices  2   b ,  2   b ′, sliding struts  11 ,  11 ′ run between the supporting struts  12 ,  12 ′ and those end regions of the main struts  10 ,  10 ′ which are directed toward the front rolling device  2   a . The sliding struts  11 ,  11 ′ are fastened on the main struts  10 ,  10 ′ and on the supporting struts  12 ,  12 ′ by means of articulation devices  30 ,  30 ′. 
   The lower articulation devices  30 ,  30 ′ can be moved along the main struts  10 ,  10 ′ and/or the supporting struts  12 ,  12 ′, and fixed, in each case together with the associated sliding strut  11 ,  11 ′. It is thus possible to set the points, defined by the articulation devices  30 ,  30 ′ at which the sliding struts  11 ,  11 ′ are articulated on the main struts  10 ,  10 ′ and/or on the supporting struts  12 ,  12 ′. 
   The sliding struts  11 ,  11 ′ each comprise two sub-struts and an adjustment device  33 ,  33 ′. The two sub-struts can be moved telescopically one inside the other such that the overall length of the sliding struts  11 ,  11 ′ is thus changed and a set length of the sliding struts  11 ,  11 ′ can be fixed by means of the adjustment device  33 ,  33 ′. It is thus possible to vary the wheel base, i.e. the distance between the front wheel  20   a  and the center of the imaginary connecting line between the two rear wheels  20   b ,  20   b ′. These sliding struts  11 ,  11 ′ thus constitute a possible embodiment of the adjusting device for the trolley frame  1 , which is intended for setting the wheel base between the front rolling device and the rear rolling devices. 
   The adjustment devices  33 ,  33 ′ are designed, for example, as screw-action/clamping connectors which allow the length of the sliding struts  11 ,  11 ′ to be set in a stepless manner. It is likewise conceivable, however, for the adjustment device  33 ,  33 ′ to be designed as an arrestable bolt which can be guided through corresponding bores of the two elements of the sliding struts  11 ,  11 ′, which can be displaced telescopically one inside the other such that the bolt fixes a set length of the sliding strut  11 ,  11 ′. In the case of this embodiment, stepwise length adjustment of the sliding struts  11 ,  11 ′ is only possible in accordance with the spacing of the bores in the two sub-struts of the sliding struts  11 ,  11 ′. 
   Between the two essentially parallel supporting struts  12 ,  12 ′, a first essentially horizontally arranged transverse strut  13 ′ runs in the region of the main struts  10 ,  10 ′. A second transverse strut  13  runs in the region of the rear rolling devices  2   b ,  2   b ′. The transverse struts  13 ,  13 ′ each have an arrestable folding articulation  32 ,  32 ′ in their center. 
   The folding articulations  32 ,  32 ′ are designed such that they divide up the transverse struts  13 ,  13 ′ into two elements of equal length which can be folded in relation to one another once the arresting action of the folding articulations  32 ,  32 ′ has been released. 
   In order to stiffen the trolley frame  1  defined by the main struts  10 ,  10 ′, the sliding struts  11 ,  11 ′, the supporting struts  12 ,  12 ′ and the transverse struts  13 , 13 ′, the bottom transverse strut  13  has two stabilizing arms  133 . The stabilizing arms  133  run obliquely upward onto the supporting struts  12 ,  12 ′ from those end regions of the bottom transverse strut  13  which are directed toward the supporting struts  12 ,  12 ′. As a result, the rectangle defined by the supporting struts  12 ,  12 ′ and the transverse struts  13 ,  13 ′, and thus the trolley frame  1  as a whole, is stiffened against shearing. 
   The strut elements  10 ,  10 ′,  11 ,  11 ′,  12 ,  12 ′,  13 ,  13 ′,  133  form a trolley frame  1  which defines a pyramid-like cage, the rectangular base surface of this pyramid-like cage being formed by the supporting struts  12 ,  12 ′ and the transverse struts  13 ,  13 ′. The sliding struts  11 ,  11 ′ and main struts  10 ,  10 ′, which extend into the region of the front rolling device  2   a  starting from the supporting struts  12 ,  12 ′, form the edges of the pyramid-like cage. The “height” of the pyramid may be varied here by virtue of the variable length adjustment of the sliding struts  11 ,  11 ′. It is possible for the person who is to be transported and/or the article which is to be transported to be fixed within the frame cage by means of a suitable accommodating device fastened on the trolley frame  1 . The space enclosed by the strut elements is increased somewhat more on account of the upwardly directed concave curvature of the main struts  10 ,  10 ′. Moreover, the main struts  10 ,  10 ′ fulfill a protective function by serving as a rollover bar in the event of the transport trolley tilting over. Moreover, it is possible for a sunshade or rain cover to be arranged along the main struts  10 ,  10 ′, which is fixed in a releasable manner on the trolley frame  1 , for example, by means of hook-and-loop fasteners or rubber bands. 
   Arranged at those ends of the main struts  10 ,  10 ′ which are directed toward the front rolling device  2   a  is a bearing device  22 , in which a bearing arm  23  is mounted such that it can be rotated about an essentially vertically arranged steering axis A. The front rolling device  2   a  is arranged at that end of the bearing arm  23  which is directed away from the bearing device  22 . The wheel  20   a  of the front rolling device  2   a  is thus mounted on the trolley frame  1  such that it can be rotated about the steering axis A via the bearing arm  23 . 
   Handle devices  14 ,  14 ′ are fastened, via fixable upper rotary articulations  31 ,  31 ′, at those ends of the main struts  10 ,  10 ′ which are directed away from the bearing device  22 . The handle devices  14 ,  14 , are used, by a person who is moving the transport trolley, for the purpose of pushing or pulling and steering the transport trolley. The upper rotary articulations  31 ,  31 ′ assigned to the handle devices  14 ,  14 ′ are designed such that they allow a height adjustment of the handle devices  14 ,  14 ′ for adaptation to the height of a person who is moving the transport trolley. Furthermore, the handle devices  14 ,  14 ′ each have an actuating arrangement, designed as a braking lever  15 , for a braking device (not illustrated in  FIG. 1 ) on one of the rolling devices  2   a ,  2   b ,  2   b′.    
     FIG. 2  shows the transport trolley from  FIG. 1 , the same components being provided with the same designations. In contrast to  FIG. 1 , the transport trolley in  FIG. 2  is illustrated with a wheel base between the front wheel  20   a  and the rear wheels  20   b ,  20   b ′ which has been shortened by way of the adjustable sliding struts  11 ,  11 ′. 
   This allows the overall length of the transport trolley to be shortened easily and straightforwardly, with the result that the transport trolley, for example when used as a stroller, is shorter and thus easier to maneuver. Moreover, the transport trolley with the shortened wheel base requires less stowage space, which is often a critical factor for strollers. 
   Furthermore, the two supporting struts  12 ,  12 ′ in  FIG. 2  have two coupling elements  16 ,  16 ′ for coupling the transport trolley to a wheelchair. 
   It is thus possible for the transport trolley to be coupled to a wheelchair, with the result that a person who has to rely on a wheelchair is provided, by way of the transport trolley, with an additional means of transporting a person and/or an article which is to be transported. 
     FIG. 3  shows the transport trolley from  FIG. 1 , the same components, once again, being provided with the same designations. In contrast to  FIG. 1 , in the case of the transport trolley in  FIG. 3 , the front rolling device  2   a  is illustrated in a state in which it has been pivoted upward together with the bearing arm  23 . The pivot axis of the bearing arm here, in the region of those ends of the main struts  10 ,  10 ′ which are directed toward the bearing device, are arranged essentially horizontally. The pivoted front wheel  20   a  ends up located in the region of the points of articulation between the sliding struts  11 ,  11 ′ and the main struts  10 ,  10 ′. In the pivoted position, the front rolling device  2   a  is secured on the trolley frame  1  by fixing means (not illustrated) such that it does not roll back in an undesirable manner. In addition, in the region of the bearing device  22  of the front rolling device  2   a , the trolley frame  1  has a coupling means  17  which allows the transport trolley to be coupled to a towing vehicle, in particular to a bicycle “B”. 
   By virtue of the front rolling device  2   a  being pivoted upward, the transport trolley can be converted quickly and straightforwardly into a trailer. For use of the transport trolley as a trailer, it is advantageous for the rear rolling devices  2   b ,  2   b ′ to be designed such that the distance between the rear wheels  20   b ,  20   b ′ can be made greater, in order to increase the tilting moment of the transport trolley utilized as a trailer. Moreover, the additional pivoting of the front rolling device  2   a  makes it possible for the frame  1  of the transport trolley to be collapsed to an even smaller state than is illustrated in  FIGS. 8   a  and  8   b.    
     FIG. 4  illustrates the transport trolley from  FIG. 1 , the difference from  FIG. 1  being that a device  4  for accommodating a person who is to be transported has been arranged on the trolley frame  1 . In particular for using the transport trolley as a stroller, the accommodating device  4  is designed as a suitable child seat with a height-adjustable footrest  40  and an inclination-adjustable backrest  41 . 
     FIG. 5 , in contrast to the illustration of  FIG. 4 , illustrates, as an alternative, an arrangement  4  for accommodating an article which is to be transported in the transport trolley. 
   The accommodating arrangement  4 , of course, may be adapted to the specific properties and dimensions of the article which is to be transported. It is thus possible to provide fastening means which are matched specifically to the article which is to be transported. A possible example would be fastening means matched to a drinks crate or a golf bag. 
   Of course, it is also possible for the accommodating arrangement  4  to be designed for the combined transportation of people and goods. 
   The folding mechanism of two different embodiments of the transport trolley will be explained in more detail with reference to  FIGS. 6   a  to  8   b.    
     FIG. 6   a  shows the first embodiment of the transport trolley from  FIG. 1 . In contrast to  FIG. 1 ,  FIG. 6   a  illustrates the folding articulations  32 ,  32 ′ of the transverse struts  13 ,  13 ′ in the unlocked state, with the result that the folding articulations  32 ,  32 ′, which are arranged in the center of the transverse struts  13 ,  13 ′, allow the two rear rolling devices  2   b ,  2   b ′ to be brought together. 
   In the case of the embodiment shown in  FIG. 6   a , the transverse struts  13 ,  13 ′ can be folded in an essentially horizontally arranged plane. 
     FIG. 6   b  illustrates a second embodiment of the transport trolley. In contrast to the first embodiment shown in  FIG. 6   a , the supporting struts  12 ,  12 ′ of the trolley frame  1  are of telescopically length-adjustable design. For this purpose, in a manner similar to the sliding struts  11 ,  11 ′, they have adjustment devices  34 ,  34 ′ for setting the length of the supporting struts  12 ,  12 ′. As far as the design of the telescopically adjustable supporting struts  12 ,  12 ′ and of the associated adjustment devices  34 ,  34 ′ is concerned, refer to the configurations in respect of the telescopically adjustable sliding struts  11 ,  11 ′ in  FIG. 1 . 
     FIG. 6   c  shows a schematic view of the two rear rolling devices  2   b ,  2   b ′ with the supporting struts  12 ,  12 ′, the bottom transverse strut  13 , in contrast to the embodiments shown in  FIGS. 6   a  and  6   b ′, being designed such that it can be collapsed in an essentially vertically arranged plane by means of the folding articulation  32 . 
   This embodiment is used both for the variant of the transport trolley which is shown in  FIG. 6   a  and for that which is shown in  FIG. 6   b.    
     FIG. 7   a  shows the first embodiment of the transport trolley from  FIG. 6   a . In a further step for collapsing the transport trolley, the points, defined via the articulation devices  30 ,  30 ′ on the supporting struts  12 ,  12 ′, at which the sliding struts  11 ,  11 ′ are articulated on the supporting struts  12 ,  12 ′ have been displaced into those end sections of the supporting struts  12 ,  12 ′ which are directed toward the main struts  10 ,  10 ′. There is no need here to change the length of the sliding struts  11 ,  11 ′ which have been set by the adjustment devices  33 ,  33 ′. 
   In the final folding step for the first embodiment of the transport trolley shown in  FIGS. 6   a  and  7   a , the rear rolling devices  2   b ,  2   b ′ as shown in  FIG. 8   a , are pivoted in the direction of the front rolling device  2   a  about a pivot axis which is defined by the articulation devices  31 ,  31 ′ between the supporting struts  12 ,  12 ′ and the main struts  10 ,  10 ′. It is thus possible for the trolley frame  1  of the first embodiment of the transport trolley to be collapsed to a compact size. 
     FIGS. 6   b  to  8   b  correspondingly show the operation for collapsing the trolley frame  1  of the second embodiment of the transport trolley.  FIG. 7   b  illustrates how the supporting struts  12 ,  12 ′ are shortened by means of the adjustment devices  34 ,  34 ′ so as to reduce the height of the transport trolley. At the same time, it is likewise possible for the length of the sliding struts  11 ,  11 ′ to be shortened by means of the associated adjustment devices  33 ,  33 ′. 
   In the final adjustment step, the rear rolling devices  2   b ,  2   b ′ are pivoted, in a manner analogous to the illustration from  FIG. 8   a , in the direction of the front rolling device  2   a.    
   In respect of the above-described folding operation for two different embodiments of the transport trolley according to the invention, it should also be emphasized that the device  4  (not illustrated in  FIGS. 6   a  to  8   b ) for accommodating people who are to be transported and/or goods which are to be transported either is released from the trolley frame  1  before the transport trolley is collapsed or is designed such that it can be folded together with the trolley frame  1 . In particular an accommodating device  4  configured as a child seat may be produced, for example, from textile material and designed such that the trolley frame  1  can be folded together with the child seat in accordance with the sequence illustrated in  FIGS. 6   a  to  8   b.    
   The front rolling device  2   a  is preferably of pivotable design, as is illustrated in  FIG. 3 . This makes it possible, for the embodiments of the transport trolley which are shown in  FIGS. 6   a  to  8   b , to achieve an even smaller packing size when the trolley frame  1  is collapsed. The folding steps shown in  FIGS. 6   a  to  8   b  are then additionally supplemented by the pivoting of the front rolling device  2   a  according to the illustration in  FIG. 3 . 
     FIG. 9  shows a detailed view of the left-hand rear rolling device  2   b , as seen in the transporting direction T, with the spring-mounting arrangement  21 . The wheel  20   b  of the rolling device  2   b  is mounted in a bearing element  213 , arranged along an axis X, such that it can be rotated about the axis X. Two parallel pivoting arms  211  and  212  of essentially equal length extend from the top and bottom end sections of the bearing element  213 . The pivoting arms  211 ,  212  have their end which is directed toward the bearing element  213  articulated on the bearing element  213  such that they can be pivoted about an axis which is oriented essentially perpendicular to the axis X and essentially horizontal. Those ends of the pivoting arms which are directed away from the bearing element  213  are articulated on the trolley frame  1 , in the bottom end region of the supporting strut  12 , such that they can be pivoted in each case about parallel axes. The two pivoting arms  211 ,  212  in this arrangement describe two opposite edges of a parallelogram which, by virtue of the pivotable articulation of the pivoting arms  211 ,  212 , shears relative to the trolley frame  1  when the wheel  20   b  moves. In order to cushion and to damp this shearing movement, a transverse arm  214  is arranged between the two pivoting arms  211 ,  212 , the bottom end of said transverse arm being articulated on a spring rod  215  projecting out of the bottom end of the supporting strut  12 . The spring rod  215  is in operative connection with a spring element arranged in the interior of the supporting strut  12 , such that, when the spring rod  215  moves into the supporting strut  12 , the spring element applies a force counter to the movement direction of the spring rod  215 . When the wheel  20   b  moves relative to the supporting strut  12 , the shearing of the pivoting arms  211 ,  212  thus causes a corresponding movement of the transverse arm  214  relative to the supporting strut  12 . Since the transverse arm  214  is articulated on the spring strut  215 , the relative movement between the transverse arm  214  and supporting strut  12  is converted into a relative movement between the spring strut  215  and supporting strut  12 . 
   The suspension of the rear wheels  20   b  and  20   b ′ which is illustrated in  FIG. 9 , furthermore, has the advantage that increasing weight of the article which is to be transported and/or of the person who is to be transported, even in the rest state of the transport trolley, results in increased deflection of the spring strut  215  into the supporting strut  12  and thus, on account of the upwardly moving pivoting arms  211 ,  212 , in a greater distance between the two rear wheels  20   b  and  20   b ′. The tilting stability of the transport trolley is thus automatically increased when the transporting load is increased. 
   Connected in a rotationally fixed manner to the axle running along the axis X, the rolling device  2   b , furthermore, has a brake disk  251 . The rotation of this brake disk  251  can be braked in a conventional manner by means of a braking arrangement  25  (not illustrated in  FIG. 9 ) arranged on the bearing element  213 . 
   The spring element which is arranged in the interior of the supporting strut  12  (and is not illustrated in  FIG. 9  either) may be designed purely mechanically and also pneumatically or hydraulically and, in addition to providing the spring property, also acts, at the same time, as a shock absorber. The entire spring-mounting arrangement  21  may be designed such that the spring excursion, i.e. the relative movement between the spring rod  215  and supporting strut  12  is at least one fifth of the diameter of the wheel  20   b . It is thus easily possible to provide the transport trolley according to the invention not with maintenance-intensive pneumatic tires which are susceptible to defects, but, for example, with maintenance-free solid-rubber tires for the wheel  20   b , or to do away with tires altogether and to provide wheels made of plastic or metal. 
   The spring-mounting arrangement  21  shown in  FIG. 9  is arranged in a correspondingly mirror-inverted manner on the second rear rolling device  2   b′.    
   As is illustrated in  FIG. 10 , the front rolling device  2   a  also has a spring-mounting arrangement  21 , as is described in  FIG. 9 . In this case, the pivoting arms  211 ,  212  on the front rolling device  2   a  are correspondingly articulated in a pivotable manner on the bearing arm  23  of the front wheel  20   a , the bearing element  213  (shown in  FIG. 9 ) together with the front wheel  20   a  being arranged in a state in which it has been rotated through 90° in relation to the illustration in  FIG. 9 . The spring element assigned to the spring-mounting arrangement  21  of the front rolling device  2   a  is correspondingly arranged in the interior of the bottom end section of the bearing arm  23  of the front wheel  20   a.    
   The top end of the bearing arm  23 , as is already illustrated in  FIG. 1 , is mounted, such that it can be pivoted about an essentially vertically arranged axis A, in a bearing device  22  arranged at the front ends of the main struts  10 ,  10 ′, said ends converging in a V-shaped manner. In the region of the bearing device  22 , the front rolling device  2   a  has a restoring device  28 . This restoring device  28  comprises an eccentric bolt  281 , which is arranged at the top end of the bearing arm  23  in an eccentric manner in relation to the axis of rotation A, and two restoring elements  282 ,  283 , which butt against the eccentric bolt  281 . The restoring elements  282 ,  283  are of elongate design, one end butting against the eccentric bolt  281  and the other end being fixed on the bearing device  22 . In the straight-ahead position of the front wheel  20   a , i.e. when the latter is oriented essentially parallel to the rear wheels  20   b ,  20   b ′, the eccentric bolt  281  is arranged essentially symmetrically to the two restoring elements  282 ,  283 , and the restoring elements  282 ,  283  do not subject the eccentric bolt  281  to any force. 
   Upon rotation of the front wheel  20   a  and thus of the bearing arm  23  about the axis A, the eccentric bolt  281  deflects one of the two restoring elements  282 ,  283  transversely to the direction in which it extends. The deflected restoring element  282 ,  283 , which is fixed on the bearing device  22  by way of its end which is directed away from the eccentric bolt  281 , is formed from a flexurally elastic material, for example from a suitable steel, with the result that the deflected, i.e. bent restoring element  282 ,  283  does not subject the eccentric bolt  281  to any force. On account of the eccentric bolt  281  being arranged eccentrically relative to the axis of rotation A, the restoring force exerted by the restoring element  282 ,  283  gives rise to a torque which is directed onto the position of the eccentric bolt  281  corresponding to a straight-ahead position of the front wheel. In order to deflect the front wheel  20   a  of the transport trolley, the person who is moving the transport trolley thus has to use the handle arrangements  14 ,  14 ′ and/or the coupling elements  16 ,  16 ′ to exert a torque which is greater than the restoring torque produced by the restoring device  28 . The restoring device  28  makes it easier, following a steering operation of the transport trolley, to restore the front wheel  20   a  into the straight-ahead position. 
   The restoring device  28  is also used for tracking stabilization of the transport trolley during movement in a transporting direction T. The restoring device prevents the situation where, in particular when the transport trolley is moving quickly over terrain, torques which are caused by unevennesses in the ground and act on the front wheel  20   a  result in the front wheel  20   a  suddenly being deflected to a pronounced extent. Such undesired movements of the front wheel  20   a , in particular when the transport trolley is moving quickly, may result in the trolley tilting over. As a further safeguard, provision is made for the bearing device  22  of the front wheel  20   a  to be designed such that the front wheel  20   a  is mounted such that it can be rotated, out of the straight-ahead position, exclusively over an angle range of around 80° to the left and around 80° to the right. 
   Of course, the restoring device  28  may also be designed with restoring elements  282 ,  283  in the form of leaf springs or helical springs. The only essential factor is the above-described functional interaction of the components of the restoring device  28 , which, in particular, achieves the desired tracking stabilization. 
   The front rolling device  2   a  which is illustrated in  FIG. 10  is designed, as has already been described in conjunction with  FIG. 3 , such that it can be pivoted about an essentially horizontally running pivot axis  102  arranged in the region of those ends of the main struts  10 ,  10 ′ which are directed toward the bearing device  22 . In the illustration shown in  FIG. 10 , a fixing element  221  arranged on the bearing device  22  secures the front rolling device  2   a  against pivoting about the pivot axis  102 . For this purpose, the fixing element  221  is connected in a releasable manner to a crossmember  101  which runs between the end regions of the main struts  10 ,  10 ′. Since the two main struts  10 , 10 ′ are coupled mechanically to the bearing device  22  and the bearing arm  23  via the fixing element  221 , the non-cushioned forces which act on the front wheel are introduced into the two main struts  10 ,  10 ′. 
   If the front rolling device  2   a , together with the bearing device arranged on the trolley frame  1 , is to be pivoted about the pivot axis  102  in the direction of the pyramid-like cage of the trolley frame  1 , the fixing element  221  has to be released from the crossmember  101  beforehand. In the pivoted position provided for use as a vehicle trailer, the front rolling device  2   a  is fixed in a releasable manner on the trolley frame via fixing means which are not illustrated in  FIG. 10 . 
   In conjunction with the above-described features, i.e. the wheel-base setting, the spring-mounting arrangement of the rolling devices, the upwardly pivotable front rolling device and the restoring device of the front wheel, the transport trolley provided is one which can be adapted to the respectively required conditions, is thus very flexible to use and is designed in a robust manner such that it is suitable for all terrains. On account of the collapsible trolley-frame construction, the transport trolley, in addition, can also be collapsed to a very small packing size and is thus suitable, in particular, for transportation in motorized vehicles.