Abstract:
A juvenile stroller includes a foldable frame, wheels coupled to the foldable frame, and a seat coupled to the foldable frame. The frame can be folded to assume a compact size and unfolded to position the seat relative to the wheels to transport a child sitting in the juvenile seat.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority to Netherlands Application No. 2004371, filed Mar. 9, 2010, which application is hereby incorporated in its entirety herein. 
       BACKGROUND 
       [0002]    The present disclosure relates to a stroller for transporting young children, and in particular to a stroller including a seat and a foldable frame coupled to the seat. More particularly, the present disclosure relates to stroller frames that fold to assume a compact size. 
       SUMMARY 
       [0003]    A stroller in accordance with the present disclosure includes a foldable frame, wheels coupled to the foldable frame, and a seat coupled to the foldable frame. The foldable frame includes at least one front leg, at least one rear leg mounted for pivotable movement relative to the front leg, and at least one push arm mounted for pivotable movement relative to the front leg. 
         [0004]    In illustrative embodiments, the foldable frame includes an arm gear coupled to the push arm and mounted to rotate about an arm pivot axis associated with the front leg during pivoting movement of the push arm relative to the front leg about that arm pivot axis. The foldable frame also includes a rear-leg gear coupled to the rear leg and mounted to rotate about a rear-leg pivot axis also associated with the front leg and to mesh with the arm gear to establish a pivot-control system. In operation, owing to the meshing of the arm and rear-leg gears, pivoting movement of the push arm about the arm pivot axis relative to the front leg causes pivoting movement of the rear leg about the rear-leg axis relative to the front leg. Pivoting movement of the push arm toward the front leg causes the rear leg to pivot toward the front leg to establish a collapsed storage configuration of the stroller. In contrast, pivoting movement of the push arm away from the front leg causes the rear leg to pivot away from the front leg to establish an expanded use configuration of the stroller. 
         [0005]    In illustrative embodiments, the foldable frame of the stroller includes first and second side-frame assemblies. Each side-frame assembly includes a front leg, a rear leg, and a push arm. Each side-frame assembly also includes a foot part coupled for swiveling movement to a lower end of the companion front leg, an outer stretcher part coupled for swiveling movement to a lower end of the companion rear leg, and a handle part coupled for swiveling movement to an upper end of the companion push arm. To enhance compact folding of the foldable frame, the two foot parts are pivotably coupled to one another, the two handle parts are pivotably coupled to one another, and each of the two outer stretcher parts is pivotably coupled to a middle stretcher part interposed between the two outer stretcher parts. 
         [0006]    In illustrative embodiments, the stroller also includes a swivel-control system configured to provide means for swiveling each of the foot parts, outer stretcher parts, and handle parts about companion swivel axes relative to companion front legs, rear legs, and push arms to cause the first side-frame assembly and the second side-frame assembly to move relative to one another to a drawn-together position in which the side-frame assemblies are located closer to one another to a spread-apart position in which the side-frame assemblies are located farther apart from one another in response to pivoting movement of the push arms relative to the front and rear legs. In an illustrative embodiment, the swivel-control system comprises a first operating element associated with each of the front legs in the side-frame assemblies, a second operating element associated with each of the rear legs in the side-frame assemblies, and a third operating element associated with each of the push arms in the side-frame assemblies. Three curved swivel-trigger rods and three extension elements are included in swivel-control system and cooperate to provide means for swiveling the swivelable parts of the front leg, the rear leg, and the push arm, respectively. 
         [0007]    Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The detailed description particularly refers to the accompanying figures in which: 
           [0009]      FIG. 1  is a perspective view of a stroller according to the present disclosure, with the stroller in an unfolded position; 
           [0010]      FIG. 2  is a perspective view of a stroller as shown in  FIG. 1  according to the present disclosure, with the stroller in a partly folded position; 
           [0011]      FIG. 3  is a perspective view of a stroller as shown in  FIG. 1  according to the present disclosure, with the stroller in a folded position; 
           [0012]      FIG. 4  is a cross section showing the function of a central part of an assembly of the stroller as shown in  FIG. 1 ; 
           [0013]      FIGS. 5A-5C  are cross sections of a central part of an assembly of the stroller as shown in  FIG. 1 , in an unfolded position, a partly folded position, and a folded position of the stroller, respectively; 
           [0014]      FIGS. 6A and 6B  are perspective views of a first embodiment of pivotably interconnected parts in an unfolded position and a folded position of the stroller, respectively; 
           [0015]      FIGS. 7A and 7B  are schematic front views of the first embodiment as shown in  FIGS. 6A and 6B , respectively, 
           [0016]      FIGS. 8A and 8B  are schematic front views of a second embodiment of two pivotably interconnected parts in an unfolded position and a folded position of the stroller, respectively, and 
           [0017]      FIG. 9  us a schematic view of a third embodiment of pivotably interconnected parts in an unfolded position. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIGS. 1 ,  2 , and  3  show perspective views of a stroller  1  according to the disclosure in an unfolded position, a partly folded position, and a folded position, respectively. Stroller  1  is provided with a foldable frame  2  and a seat  2 S configured to be detachably connected to frame  2  as suggested in  FIG. 1 . Frame  2  is provided with a first side-frame assembly  3  and a second side-frame assembly  4 . Each side-frame assembly  3 ,  4  is provided with a first (front) leg  5 , a second (rear) leg  6 , and a push arm  7 . Legs  5 ,  6 , and push arms  7  are illustratively made of hollow tubes of metal or plastic. 
         [0019]    A pivot-control system  70  is coupled to push arm  7  and first and second legs  5 ,  6  of each of first and second side-frame assemblies  3 ,  4  of foldable frame  2  as suggested in  FIG. 1 . Each pivot-control system  70  is configured and mounted to provide means for moving a second leg  6  relative to companion first legs  5  to cause companion first and second legs  5 ,  6  to move relative to one another between expanded use positions shown, for example, in  FIG. 1  and retracted storage positions shown, for example, in  FIG. 4  in response to movement of companion push arms  7  relative to companion first and second legs  5 ,  6  as suggested in  FIGS. 2 and 5A . In illustrative embodiments, each pivot-control system  70  comprises a first (arm) gear part  15  coupled to the push arm  7  and mounted for pivotable movement about a first (arm) pivot axis  9  associated with companion first leg  5  and a second (rear-leg) gear part  17  coupled to the second leg  6  to mesh with first (arm) gear part  15  and mounted for pivotable movement about a second (rear-leg) pivot axis  10  associated with companion first leg  5 . 
         [0020]    Each first (front) leg  5  is provided near a lower first end with a front wheel  8  and near an upper second end with two pivot axes  9 ,  10  (see  FIG. 4-5C ). Near the lower first ends the first legs  5  are connected to each other by means of two foot parts  11 . The foot parts  11  are pivotably connected to each other about a foot pivot axis  12  as suggested in  FIGS. 1-3 . Each foot part  11  is swivelably connected to its corresponding first leg  5  about a swivel axis  40  as suggested in  FIG. 6A . 
         [0021]    Each push arm  7  is provided near an upper first end with a handle part  13  being pivotably connected to each other about a handle pivot axis  14  as suggested in  FIG. 1 . Each handle part  13  is swivelably connected to its corresponding push arm  7  about a swivel axis  140  as suggested in  FIGS. 2 and 3 . Each push arm  7  is provided near a lower second end with a first (arm) gear part  15  being pivotable about the first pivot axis  9  of the companion first leg  5  as suggested in  FIG. 5A . The first (arm) gear part  15  comprises teeth around its whole circumference in an illustrative embodiment as suggested in  FIGS. 5A-5C . 
         [0022]    Each second (rear) leg  6  is provided near a lower first end with a rear wheel  16  and near an upper second end with a second (rear-leg) gear part  17  being pivotable about the second pivot axis  10  of the companion first leg  5  as suggested in  FIG. 5A . The second (rear-leg) gear part  17  comprises teeth around a limited section of its circumference in an illustrative embodiment as suggested in  FIGS. 5A-5C . The gear parts  15 ,  17  of the push arm  7  and the second leg  6  are in mesh with each other as suggested in  FIGS. 5A-5C . 
         [0023]    Near the lower first ends, the second legs  6  are connected to each other by means of three stretcher parts  18 ,  19 , and  18  wherein the middle stretcher part  19  is located between two outer stretcher parts  18 . Each of the outer stretcher parts  18  is pivotably connected to the middle stretcher part  19  about a pivot axis  20  to provide two spaced-apart pivot axes  20  as shown, for example, in  FIG. 1 . Each outer stretcher part  18  is swivelably connected to its corresponding second leg  6  about a swivel axis  140  as suggested in  FIGS. 2 and 3 . 
         [0024]    Each side-frame assembly  3 ,  4  of foldable frame  2  is further provided with a lock  21  being slidably located in the push arm  7  as shown, for example, in  FIG. 4 . The lock  21  comprises a first protrusion  22  being located in an opening  23  in the first (front) leg  5  to prevent the pivoting of the push arm  7  with respect to the companion first (front) leg  5 . The lock  21  comprises a second protrusion  24  being in abutment with a pivot-blocking part  25  of the second (rear) leg  6  to prevent the pivoting of the push arm  7  with respect to the companion second (rear) leg  6 . 
         [0025]    The lock  21  is movable against spring force Fs generated by any suitable spring in a direction as indicated by arrow P 1  by means of a knob  26  as suggested in  FIG. 4 . The knob  26  is connected to the lock  21  by a cable  27 . The lock  21  and cable  27  are illustratively located inside the hollow push arm  7  so that they are hidden from view, while the knob  26  extends partly outside the push arm  7  so that a user can operate the knob  26 . 
         [0026]    A swivel-control system  80  is configured to provide means for swiveling each of the foot parts  11 , outer stretcher parts  18 , and handle parts  13  about companion swivel axes  40 ,  240 ,  140  relative to companion first (front) legs  5 , second (rear) legs  6 , and push arms  7  as suggested in  FIGS. 1-3  to cause the first side-frame assembly  3  and the second side-frame assembly  4  to move relative to one another to a spread-apart first position shown, for example, in  FIG. 1  in which the assemblies  3 ,  4  are located farther apart from one another to a drawn-together second position shown, for example, in  FIG. 3  in which the assemblies  3 ,  4  are located closer to one another in response to movement of push arms  7  in direction P 2  relative to first and second legs  5 ,  6  as suggested in  FIGS. 2 and 5A . In an illustrative embodiment, swivel-control system comprises a first operating element  81  associated with each of the first (front) legs  5  in side-frame assemblies  3 ,  4 , a second operating element  82  associated with each of the second (rear) legs  6  in side-frame assemblies  3 ,  4 , and a third operating element  83  associated with each of the push arms  7  in side-frame assemblies  3 ,  4  as suggested in  FIGS. 1 and 5A .  FIGS. 5A-5C  show that three curved swivel-trigger rods  28 ,  29 ,  30  and that three extension elements  146 ,  246 ,  34  are included in swivel-control system  80  and cooperate to provide means for swiveling the swivelable parts  11 ,  18 ,  13  of the first leg  5 , the second leg  6 , and the push arm  7 , respectively, as suggested in  FIGS. 5A-5C  and  FIGS. 1-3 . 
         [0027]    First operating element  81  of swivel-control system  80  comprises a first swivel-trigger rod  28 , a first-end pivot axle  31 , a second-end pivot axle  32 , a first extension element  146 , and a first motion-transfer link  810  coupled to first extension element  146  and a companion foot part  11  as suggested in  FIG. 5A . In illustrative embodiments, first motion-transfer link  810  is configured to provide means for moving a companion foot part  11  about foot pivot axis  12  relative to a neighboring foot part  11  as suggested in  FIGS. 6A and 6B  in response to movement of first extension element  146  relative to companion first (front) leg  5 . In illustrative embodiments, first motion-transfer link  810  comprises a pin  47  coupled to first extension element  146  and a guiding element  44  coupled to a second section  42  of foot part  11  to move therewith and formed to include a slot  45  receiving pin  47  for reciprocating sliding movement therein as suggested in  FIGS. 6A and 6B . 
         [0028]    A first end of the first swivel-trigger rod  28  is pivotably connected to a pivot axle  31  coupled to second leg  6  for pivotable movement about a pivot axis  31 A relative to the second leg  6  as suggested in  FIGS. 5A-5C . A second end  32 E of the first swivel-trigger rod  28  is connected to a first end of a first extension element  146  of the first operating element  81  using any suitable pivot coupling  32  to support first extension element  146  for pivotable movement about pivot axis  32 A relative to first swivel-trigger rod  28  as suggested in  FIGS. 5A-5C . First operating element  81  is connected with its other second end to the foot part  11  of the first leg  5  by means of first motion-transfer link  810  at a distance of the swivel axis  40  thereof. The first extension element  146  is located inside the hollow first leg  5  in an illustrative embodiment. 
         [0029]    Second operating element  82  of swivel-control system  80  comprises a second swivel-trigger rod  29 , a first-end pivot axle  33 , a second-end pivot axle  34 , a second extension element  246 , and a second motion-transfer link  820  coupled to second extension element  246  and a companion outer stretcher part  18  as suggested in  FIG. 5A . In illustrative embodiments, second motion-transfer link  820  is configured to provide means for moving a companion outer stretcher part  18  about a pivot axis  20  relative to a neighboring middle stretcher part  19  as suggested in  FIGS. 1-3  in response to movement of second extension element  246  relative to companion second (rear) leg  6 . In illustrative embodiments, second motion-transfer link  820  includes components similar to the components included in first motion-transfer link  810  as shown in  FIGS. 6A and 6B . 
         [0030]    A first end of the second swivel-trigger rod  29  is pivotably connected to a pivot axle  33  for pivotable movement about a pivot axis  33 A relative to the first leg  5  as suggested in  FIGS. 5A-5C . A second end  34 E of the second swivel-trigger rod  29  is connected to a first end of a second extension element  246  of the second operating element  82  which is connected with its other second end to the outer stretcher part  18  of the second leg  6  by means of second motion-transfer link  820  at a distance of the swivel axis  240  thereof. The second extension element  246  is located inside the hollow second leg  6  as suggested diagrammatically in  FIG. 5A . 
         [0031]    Third operating element  83  of swivel-control system  80  comprises a third swivel-trigger rod  30 , a first-end pivot axle  35 , a second-end pivot axle  36 , a third extension element  346 , and a third motion-transfer link  830  coupled to third extension element  346  and a companion handle part  13  as suggested in  FIG. 5A . In illustrative embodiments, third motion-transfer link  830  is configured to provide means for moving a companion handle part  13  about a handle pivot axis  14  relative to a neighboring handle part as suggested in  FIGS. 1-3  in response to movement of the third extension element  346  relative to companion push arm  7 . 
         [0032]    A first end of the third swivel-trigger rod  30  is pivotably connected to a pivot axle  35  for pivotable movement about a pivot axis  35 A relative to the first leg  5  as suggested in  FIGS. 5A-5C . A second end  36 E of the third swivel-trigger rod  30  is connected to a first end of a third extension element  346  which is connected with its other second end to the handle part  13  of the push arm  7  by means of third motion-transfer link  830  at a distance of the swivel axis  140  thereof. The third extension element  346  is located inside the hollow push arm  7  in an illustrative embodiment as suggested diagrammatically in  FIG. 5A . 
         [0033]    The folding of the frame  2  of the stroller  1  works as follows in an illustrative embodiment of the present disclosure. A user unlocks the locks  21  and pivots the push arms  7  about the pivot axes  9  associated with the first (front) legs  5  in the direction as indicated by arrow P 2 . By doing so, the first (arm) gear part  15  will force the second (rear-leg) gear part  17  to rotate in opposite direction indicated by arrow P 3  until the push arms  7  and the second (rear) legs  6  are located against different sides of the first (front) legs  5  (see  FIG. 5C ). While pivoting the push arms  7  and second (rear) legs  6 , the swivel-trigger rods  28 ,  29 ,  30  will be moved as well, wherein the second end  32 E of the first swivel trigger rod  28  will be moved towards the foot part  11  in the direction as indicated by arrow P 4 , the second end  34 E of the second swivel-trigger rod  29  will be moved away from the outer stretcher part  18  in the direction as indicated by arrow P 5 , and the second end  36 E of the third swivel-trigger rod  30  will be moved towards the handle part  13  in the direction as indicated by arrow P 6 . These movements will cause the extension elements  146 ,  246 ,  346  connected to the swivel-trigger rods  28 ,  29 ,  30  to be moved accordingly and will cause the parts  11 ,  18 ,  13  to swivel about their swivel axes  40 ,  240 ,  140  as will be explained here below. 
         [0034]    The connection between the swivel-trigger rods  28 ,  29 ,  30  and the swivelable parts  11 ,  18 ,  13 , respectively, and the swiveling of the parts  11 ,  18 ,  13  can be realized in several different manners in accordance with the present disclosure.  FIG. 6A-8B  show two different possibilities within the scope of the present disclosure which can each be used for swiveling foot part  11 , outer stretcher part  18 , and/or handle part  13 . 
         [0035]      FIG. 6A-6B  and  7 A- 7 B show an embodiment for swiveling foot part  11  about a swivel axis  40  connected to the first hollow leg  5 . The foot part  11  comprises a hollow L-shaped profile with a first section  41  and a second section  42 . The first section  41  is pivotably connected about the pivot axis  12  to a first section  41  of the foot part  11  of the other first leg  5 . At a side away from the pivot axis  12  the first section  41  is provided with a cylinder  43  being swivelable about the swivel axis  40  of the first leg  5 . The second section  42  is provided with a guiding element  44  comprising an elongated slot  45 . The slot  45  extends under an angle with the longitudinal direction of the first leg  5 . The first leg  5  is provided with the first extension element  146  which is pivotably connected with a first end to the second end  32  of the swivel-trigger rod  28 . The second end of the first extension element  146  is provided with a pin  47 . The pin  47  is slidably located in the slot  45  of the guiding element  44 . In the position of the foot part  11  as shown in  FIG. 6A , the pin  47  is located at the upper end of the slot  45  and the second section  42  rests against the first leg  5 . The first leg  5  is partly shown with dotted lines for the sake of clarity. When the first extension element  146  is being moved in the direction as indicated by arrow P 7 , the pin  47  will be forced to slide in the slot  45  in the direction as indicated by arrow P 8  until the pin  47  is located in the lower end of the slot  45 , wherein the foot part  11  will be forced to swivel about the swivel axis  40  in the direction as indicated by arrow P 9 . 
         [0036]    Preferably both side-frame assemblies  3 ,  4  are substantially the same in construction and function, so that also foot part  11  of the other first leg  5  will be forced to swivel. By swiveling the foot parts  11 , the side-frame assemblies  3 ,  4  will be moved towards each other from the expanded use position shown in  FIG. 1  to the retracted storage position shown in  FIG. 3 . A similar construction can be used for the handle parts  13 . 
         [0037]      FIGS. 8A and 8B  show schematically an embodiment of two pivotably interconnected outer stretcher parts  18 , wherein the outer stretcher part  18  is swivelably connected to the second hollow leg  5  about a swivel axis  240 . The second (rear) leg  6  is provided a second operating element comprising the second swivel-trigger rod  29 , a second extension element  246 , and a coupling rod  52 . The second extension element  246  is pivotably connected with a first end to the second end  34 E of the second swivel-trigger rod  29 . The second end of the second extension element  246  is pivotably connected about a pivot axis  53  to the coupling rod  52 . The coupling rod  52  is pivotably connected about pivot axis  54  to the outer stretcher part  18 . The pivot axis  54  is located between the swivel axis  240  and the pivot axis  20  (see  FIG. 1 ). When folding the frame  2  of the stroller  1 , the second end  34 E of the second swivel-trigger rod  29  will be moved in a direction as indicated by arrow P 5  causing the second extension element  246  to be moved in the direction as indicated by arrow P 10 . Due to this movement, coupling rod  52  will force the outer stretcher part  18  to swivel about the swivel axis  240  on the second (rear) leg  6 . 
         [0038]      FIG. 9  shows schematically a framework  61  of pivotably interconnected parts  62 ,  63 ,  64 ,  65 , which framework  61  can be located between a pair of legs and/or a pair of push arms. The framework  61  will be explained as if connected between the rear second legs  6 . The parts  62 ,  63 ,  64 ,  65  are made of rods. Part  62  is swivelably connected near an end of the second leg  6  at swivel axis  72  while part  63  is swivelably connected near an end of the other second leg  6  at swivel axis  73 . The parts  62 ,  63  are pivotably connected to each other at their other ends at pivot axis  66 . Part  64  is swivelably connected to an end of a rod-like operating element  67  at swivel axis  74  while part  65  is swivelably connected to an end of another rod-like operating element  67  at swivel axis  75 . The operating elements  67  are located in the second legs  6 . The parts  64 ,  65  are pivotably connected to each other at their other ends at pivot axis  68 . 
         [0039]    Furthermore, the parts  62 ,  64  and the parts  63 ,  65  are pivotably connected to each other between the swivel axes  72 ,  73 ,  74 ,  75  and the respective pivot axis  66 ,  68  at pivot axis  69 ,  70  respectively. 
         [0040]    When folding the stroller, the operating elements  67  will be moved in the direction as indicated by the arrow P 13 , due to which the swivel axes  72 ,  74  and  73 ,  75  will be moved apart and the parts  62 ,  63 ,  64 ,  65  will be swiveled in the direction as indicated by arrows P 22 , P 23 , P 24 , P 25 . As a result the swivel axes  73 ,  75  will be moved towards the swivel axes  72 ,  74  in the direction as indicated by arrow P 14  and the second legs will be moved towards each other. 
         [0041]    In case that the extension element is a rigid rod, the operating element is suitable for exerting a pulling force and a pushing force on the swivelable part and will cause the swivelable part to swivel both during folding and unfolding of the frame. In case that the operating element comprises a flexible bendable element, for example a cable, the operating element is more suitable for only exerting a pulling force on the part to cause the swivelable part to swivel during folding or unfolding of the frame. In such a case, the operating element may also comprise a spring to cause a pushing force for swiveling the part in the opposite direction. 
         [0042]    As desired, the frame  2  may comprises handles  60  on the first legs  5  for lifting the folded stroller  1 . 
         [0043]    It is also possible within the scope of the present disclosure to provide other pivotably interconnected parts between the legs or the arms to move the side-frame assemblies  3 ,  4  towards each other. 
         [0044]    It is also possible within the scope of the present disclosure to have the pivotably interconnected parts only between one pair of legs, only between the pair of push arms, only between the two pair of legs or only between one pair of legs and the pair of push arms. 
         [0045]    It is also possible within the scope of the present disclosure to have the pivotably interconnected parts located closer to the pivot axes  9 ,  10 , for example near the middle of the legs and push arms. 
         [0046]    It is also possible within the scope of the present disclosure to provide the slots  45  or similar slots with at least two parts including an angle of less than 180 degrees with each other. The first part extends in the longitudinal direction of the leg or push arm. During a first movement of the pin  47  in the first part of the slot  45  no swiveling of the foot part  11  will occur. The foot part  11  will only start swiveling as soon as the pin  47  is being moved through the second part of the slot. In this manner it is for example possible to delay the start of the swiveling of the parts between one pair of legs with respect to the start of the swiveling of parts between the other pair of legs to optimize the folding of the stroller. 
         [0047]    It is also possible within the scope of the present disclosure to provide the slots  45  or similar slots with a small recess from which the pin  47  can only be removed when a certain predetermined pulling or pushing force is applied. In this manner the recess functions as an additional lock and prevents inadvertently folding of the stroller. The first legs can also be the rear legs, in which case by folding the stroller the rear legs will become located between the arms and the front legs. 
         [0048]    The seat of the stroller may be detached from the stroller before folding the stroller or may be folded together with the stroller. 
         [0049]    The width of a stroller in accordance with the present disclosure in its folded position is substantially reduced with respect to the width of the stroller in its unfolded position. At least a pair of legs or a pair of push arms of the side-frame assemblies are connected to each other near ends avert of the pivot axes by means of at least two interconnected parts being pivotable about at least one pivot axis, each part being swivelable about a swivel axis near the end avert of the pivot axes, wherein at least one part of a leg is connected to the other leg or push arm of the same assembly, while at least one part of a push arm is connected to one of the legs of the same side-frame assembly by means of at least one operating element for swivelling at least one part with respect to the corresponding leg or push arm, wherein by pivoting the push arm and second leg with respect to the first leg from an unfolded position to a folded position, the at least one operating element is being moved, whereby the parts are being swivelled from a first position in which the side-frame assemblies are spaced apart to a second position in which the side-frame assemblies are located closer to each other, and vice versa. 
         [0050]    Due to the pivotably interconnected parts, the two side-frame assemblies can be moved towards each other when folding the frame to the folded position. By moving the side-frame assemblies towards each other the width of the folded stroller is substantially reduced. Since the operating element is connected to the swivelable part of one leg as well as to the push arm or the other leg of the same side-frame assembly or is connected to the swivelable part of the push arm as well as to one of the legs of the same side-frame assembly, the operating element will force the swivelable part to swivel automatically when the side-frame assembly is being folded. A user simply has to pivot the push arms with respect to the first legs, wherein automatically the second legs are also moved towards the first legs and the side-frame assemblies are being moved towards each other. The first legs will be located between the second legs and the push arms, the wheels connected to the four legs will be located close to each other and also the handle parts will be located close to each other. So a very compact folded stroller is obtained. 
         [0051]    A stroller in accordance with the present disclosure is characterized in that the parts are swivelable about swivel axes of the second legs, wherein the operating element is connected with its second end to the first leg. By locating the swivelable parts between swivel axis located near ends of the second legs, which ends are located avert of the pivot axes, the swivelable parts will cause the seconds legs to move towards each other when folding the frame. The other legs and push arms will follow this movement. 
         [0052]    Another embodiment of a stroller in accordance with the present disclosure is characterized in that the parts are swivelable about swivel axes of the first legs, wherein the operating element is connected with its second end to the second leg. By locating the swivelable parts between swivel axis located near ends of the first legs, which ends are located avert of the pivot axes, the swivelable parts will cause the first legs to move towards each other when folding the frame. The other legs and push arms will follow this movement. When swivelable parts are located between the first legs as well as between the second legs, the side-frame assemblies can be moved easily towards and away from each other. 
         [0053]    In case that the operating element comprises only rigid elements, the operating element is suitable for exerting a pulling force and a pushing force on the swivelable part and will cause the swivelable part to swivel both during folding and unfolding of the frame. In case that the operating element comprises a flexible bendable element, the operating element is more suitable for only exerting a pulling force on the part to cause the swivelable part to swivel during folding or unfolding of the frame. 
         [0054]    A further embodiment of the stroller in accordance with the present disclosure is characterized in that the handle parts of the push arms are swivelable about the swivel axes of the arm, wherein the operating element is connected with its second end to the first leg. By using the pivotably connected handle parts as the two pivotably interconnected parts, the swivelling of the handle parts will cause the push arms to move towards each other when folding the frame. The other legs will follow this movement, especially when also the first legs and/or second legs are also connected to each other near ends avert of the pivot axes by means of at least two pivotably interconnected parts. 
         [0055]    A further embodiment of the stroller in accordance with the present disclosure is characterized in that the side-frame assemblies are connected to each other near ends avert of the pivot axes of the pair of arms, near ends away from the pivot axes of the pair of first legs and near ends away from the pivot axes of the pair of second legs, by means of at least two pivotably interconnected parts extending between the first ends of the push arms, the first legs, and the second legs, respectively. In this manner the movement of the side-frame assemblies towards each other is very well controlled. The unfolded stroller will be very stable due to the interconnected parts located near the ends of the first legs, the ends of the second legs, and the ends of the push arms. Furthermore, the whole space between the side-frame assemblies is available for mounting a seat, a basket, or other elements. A further embodiment of the stroller in accordance with the present disclosure is characterized in that the pivotably interconnected parts are connected to each other by means of at least an intermediate part. Due to the intermediate part which is illustratively pivotably connected to the parts, any desired movement of the side-frame assemblies towards each other can be obtained. 
         [0056]    A further embodiment of the stroller according to the present disclosure characterized in that the operating element comprises at least a swivel-trigger rod being pivotably connected to the leg or the push arm and pivotably connected to an extension member located between the swivel-trigger rod and the swivelable part. Due to the rod, which might be curved to easily fit in the legs and push arms, it is possible to connect the operating element to any desired location in or on the legs or push arms. 
         [0057]    A further embodiment of the stroller according to the present disclosure is characterized in that the operating member or the swivelable part comprises a pin being slidable in a slot of the swivelable part or operating member respectively for swivelling the part about the swivel axis. Such a pin-slot construction renders it relatively easily to convert a linear movement into a rotational movement. 
         [0058]    A further embodiment of the stroller according to the present disclosure is characterized in that the frame comprises locking means for locking the gear parts against rotation. Such locking means will easily prevent the frame against being folded unintentionally.