Abstract:
A transport vehicle includes a chassis with at least two load carriers which are placed next to and at a distance from each other. The distance between the at least two load carriers are modifiable in order to modify the width of the transport vehicle. The at least two load carriers of the transport vehicle are connected to one another by at least one articulated twin-arm structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This continuation application claims priority to PCT/EP2015/001223 filed on Jun. 17, 2015 which has published as WO 2015/197173 A1 and also the German application number 10 2014 009 036.1 filed on Jun. 24, 2014 and application number 20 2014 005 055.4 filed on Jun. 24, 2014, the entire contents of which are fully incorporated herein with these references. 
     
    
     DESCRIPTION 
     Field of the Invention 
       [0002]    The invention relates to a transport vehicle, in particular a self-propelled transport vehicle, having a chassis with at least two load carriers being arranged side-by-side and spaced from each other, whose mutual distance is, for changing the width of the transport vehicle, changeable. 
       Background of the Invention 
       [0003]    For transporting loads having an excess width or for the return journey of the transport vehicle without load respectively, it is of advantage that the width of the vehicle used for transporting a heavy load can be changed. In addition, in some states of the USA special legal provisions for vehicles for transporting heavy loads are in force, by which the allowable load per axle is, depending on the track width of the vehicle, limited, so that a variable width and hence a track width is of advantage in order to comply with the legal regulations and to exploit the maximum axle load. For this purpose it is provided in the known transport vehicle that between the two parallel load carriers a central carrier is arranged and that the two load carriers are connected with the central girder by means of cross beams being variable in their length. By way of a corresponding displacement of the load girders it is therefore possible to change the width of the known transport vehicle and hence its track width. 
         [0004]    From WO 2010/048674 A1 a transport vehicle is known, which comprises two juxtaposed load girders spaced apart from each other, whose mutual distance can be varied for changing the width of the transport vehicle. Between the two load girders an X-shaped connecting element is arranged, which comprises two beams being connected by a joint arranged in the middle. The first beam runs from a front portion of the first load girder to the end portion of the second load girder, the second beam runs from a front portion of the second load girder to a rear portion of the first load girder, so that the two beams cross in their middle and are connected via a hinge. Each of the two beams is connected with the rear portion of the respective load girder and is received pivotally and slidingly in guide elements, so that they are movable along the load girder. If the two load girders are moved apart, the front ends of the two beams move along the guide elements towards the rear end of the load girders, so that the X defined by the two crossing beams broadens. For reducing the width of the vehicle the front portions of the beams are slided forwardly, so that the X defined by the crossing beams narrows. 
         [0005]    From WO 96/39320 A1 a wheel chair is known, in which the aforementioned designed principle is realized too. This wheel chair has got two longitudinal frames, between which two beams are arranged in an X-configuration. Each front end of the crossing beams is arranged in the respective longitudinal frame slidingly and the rear part of the two beams is connected firmly with the respective longitudinal frame. 
         [0006]    From U.S. Pat. No. 4,221,398 a transport vehicle of the type mentioned afore is known, having the form of a drawbar trailer and a low loader with several steering axles, whose width and track width can be increased and decreased when required, by moving two chassis parts, each having a row of wheel bogies, transverse to the direction of travel or to a vertical longitudinal central axis respectively, apart or together. The wheel bogies of each steering axle are steered there independently by separate steering cylinders, which are arranged in each of the two chassis parts. 
         [0007]    Furthermore, from U.S. Pat. No. 4,772,038, U.S. Pat. No. 5,118,245 or U.S. Pat. No. 5,326,128 transport vehicles with a variable width and track width are known. U.S. Pat. No. 3,339,942 discloses a low loader with variable track width, whose width can be reduced when driving unloaded. 
         [0008]    DE 2 219 447 A discloses a transport vehicle in the form of a low loader consisting of two traverses or load carriers, each carrying a row of successively arranged steerable wheel bogies, and two traction units. To steer the wheel bogies of both traverses simultaneously, in total four lockable and telescopable (i.e. capable of telescoping) track rods are provided, which are arranged in pairs between each of the traction units and the wheel bogies of the adjacent steering or pendulum axis. However, this means that at any adjustment of the width and the track width of the low loader the length of all four telescopable track rods must be adjusted and locked after this adjustment, which causes significant setup times. In addition, the telescopable track rods are arranged in respect to the longitudinal vehicle axis at an angle of other than 90 degrees, which also changes when adjusting the width and the track width of the low loader, so that the amount of the length adjustment of the track rods necessary does not correspond to the amount of the adjustment of the track width, but must be calculated for the different track width depending on the angular position of the track rods. In addition, the turning movement of a tractor unit results in different angular orientations of the track rods being arranged on both sides of the traction unit, so that for transmitting the pivotal movement of the traction unit to the two wheel bogies of the adjacent steering or pendulum axle it seems doubtful whether or not the steering angle of these two wheel bogies is identical, despite of a relatively complicated kinematics. 
         [0009]    It is the object of the present invention to further develop a transport vehicle, in particular a self-propelled transport vehicle, of the kind mentioned at the beginning in such a way that a width and consequently a track width adjustment is possible in a simple way. 
       SUMMARY OF THE INVENTION 
       [0010]    This object is achieved by the present invention that at least two load carriers of the transport vehicle are connected by a scissor link, that at least one scissor link comprises two arms, whose first end portions are hingedly connected with one load carrier and whose second end portions are connected via a joint, that at least one scissor link comprises two arms, so that the first end portion of the first arm is pivotally connected with the first end portion of the first arm and the first end portion of the second arm of said scissor link is pivotally connected with the second load carrier, so that the second end portion of the first arm and the second end portion of the second arm are connected via a joint. 
         [0011]    It is understood by those skilled in the art that the use of the term “load carrier” can be used interchangeably with the term “load girder” as they mean and teach the same concept of a girder/carrier that can accommodate a load. 
         [0012]    By the inventive measures in an advantageous way a transport vehicle is created, which is variable in its width and hence in its track width, which is characterized in that this width adjustment can be performed with simple means, namely with scissor links. In an advantageous way the two load carriers of the transport vehicles being connected by the scissor links are only connected by the scissor links and, preferably, by a cross beam being variable in its length. The design of the wheel arrangements carrying the load carrier is therefore not affected by the width and track width adjustability achieved by the inventive measures. 
         [0013]    An advantageous further development of the invention provides that at least one, preferably all or almost all wheel assemblies of the transport vehicle are designed steerable. Such a measure has got the advantage that the width adjustment of the inventive transport vehicle can be achieved by a respective positioning of the wheels of the wheel assemblies in conjunction with a subsequent driving movement of the transport vehicle. 
         [0014]    A further advantageous further development of the invention provides that the transport vehicle has at least one means for changing the angular position of the arms of the corresponding scissor link, which engages on at least one scissor link. Preferably it is provided that this means, in particular a double-acting cylinder, is arranged between two cooperating scissor links, so that by acting on the scissor links an adjustment of the distance of their pivot points in the direction of the load carriers can be achieved. The change of the angular position of the arms of the scissor links caused in that way results in an advantageous manner in a change of the width of the transport vehicle. 
         [0015]    Further advantageous developments of the invention are the subject matter of the depending claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further details and advantages of the invention are disclosed in the exemplary embodiments, which are described in the following with reference to the two exemplary embodiments. It shows: 
           [0017]      FIG. 1  is a perspective view of a first exemplary embodiment of a transport vehicle; 
           [0018]      FIG. 2  is a side view of the exemplary embodiment; 
           [0019]      FIG. 3  is a top view of the first exemplary embodiment at an enlarged width; 
           [0020]      FIG. 4  is a top view on the first exemplary embodiment at a reduced width; 
           [0021]      FIG. 5  is a top view on a second exemplary embodiment at an enlarged width; and 
           [0022]      FIG. 6  is a top view on the second exemplary embodiment at a reduced width. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    In  FIGS. 1 to 4  a first exemplary embodiment of a transport vehicle, generally designated with  1 , is shown, which is, in the case described here, designed as a self-propelled transport vehicle. Such self-propelled transport vehicles are known under the designation SPMT-vehicles (self-propelled modular trailer) and therefore need not be described in detail. 
         [0024]    The transport vehicle  1  comprises a chassis  2 , which has two load carriers (i.e. load girders)  2   a ,  2   b , which are arranged spaced apart and can be moved relative to each other in a transverse direction. Preferably, they are constructed identically, so that in the following only the load carrier  2   a , which is the right one in  FIG. 1 , is described in detail. Under the load carrier  2   a  a number of wheel assemblies  3  is provided, each having a dual wheel  3   a , which is connected by a pendulum axle  3   b  with a turntable  3   c  (see  FIG. 2 ) of the wheel assembly  3 . The drive energy required for driving and steering the wheel assemblies  3  is generated by a drive unit  3   d , at it is known e.g. under the designation PPU (Power Pack Unit) and therefore is not described in detail. 
         [0025]    It is essential that the two load carrier  2   a  and  2   b  of the chassis  2  are connected by two scissor links  4  and  5  with each other, each having two arms  4   a  and  4   b  and  5   a  and  5   b  respectively. A first end portion  4   a ′ and  4   b ′ respectively of the arms  4   a  and  4   b  of the first scissor link  4  is—as best seen from  FIGS. 4 and 5 —hinged movably to each of the two load carriers  2   a  and  2   b  of the chassis  2  and the two second end portions  4   a ″,  4   b ″ of the arms  4   a ,  4   b  are connected via a joint  4   c . In a corresponding way the first end portions  5   a ′ and  5   b ′ of the two arms  5   a  and  5   b  of the second scissor link  5  are pivotally connected with the load carriers  2   a  and  2   b  and their second end portion  5   a ″,  5   b ″ are connected via a joint  5   c . Each of the arms  4   a ,  4   b  and  5   a ,  5   b  of the two scissor links  4  and  5  comprises two carriers  6   a  and  6   b  being arranged one above the other, which are connected via a joint element  6   c  in such a way that the two carriers  6   a ,  6   b  produce at both ends the joint element  6   c , so that protruding end portions  6   a ′ and  6   b ′ respectively are provided, which delimit a free space. The end portion  6   a ′ and  6   b ′ of the two carriers  6   a  and  6   b  of each arm  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  therefore can be inserted between articulating elements  8   a  and  8   b  of a joint  8 , which is firmly connected with the load carriers  2   a  and  2   b . The articulation elements  8   a  and  8   b  as well as the end portions  4   a ′,  4   b ′ and  5   a ′,  5   b ′ of the arms  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  each comprise an opening  8   c , through which a bolt  8   d  of the joint  8  can be moved through, so that the arms  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  are pivotally connected with the load carriers  2   a ,  2   b.    
         [0026]    The load carriers  2   a  and  2   b  are connected firmly via a cross beam  2   c , whose length can be varied, so that the stability of the vehicle  1  is enhanced. 
         [0027]    The joints  8  comprise a means  10  for defining the angular position of the arms  4   a - 5   b  of the scissor links  4  and  5  in respect to the load carriers  2   a  and  2   b . This one has got a perforated plate  11 , which has got openings  12  forming a hole pattern, which are arranged concentrically to the pivot axis of the joints  8  provided by the bolts  8   d . Each arm  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  comprises a recess  13 , which is arranged in such a way that a bolt  14  put through one of the openings  12  of the hole pattern enters the corresponding recess  13  of the respective arms  4   a ,  4   b ,  5   a ,  5   b  and hence fixes the arm  4   a ,  4   b ,  5   a ,  5   b  in its angular position corresponding to the respective opening of the hole pattern. 
         [0028]    The width adjustment of the described vehicle  1  is now performed as follows: Firstly, the bolts  14  are removed, so that the arms  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  are not fixed in their corresponding angular position any longer. If the load carriers  2   a  and  2   b  are to be moved from their broader position shown in  FIG. 3  into their narrower position shown in  FIG. 4 , this is achieved in the described first exemplary embodiment in an advantageous way via corresponding driving movements of the transport vehicle  1 . This has got the advantage that for a width adjustment of the transport vehicle  1  no further devices as e. g. hydraulic cylinders, dual wheels, by which the load carriers  2   a  and  2   b  can be moved towards each other or away from each other, are required. To move the load carriers  2   a  and  2   b  together, the steering axles of the wheel arrangements  3  of the two load carriers  2   a  and  2   b  are positioned in such a way that the dual wheels  3   a —seen in the direction of the following driving movement—are turned inwardly. If the transport vehicle  1  is moved in said driving direction, this results that the dual wheels  3   a  move towards each other and the load carriers  2   a  and  2   b  move, due to this driving movements, inwardly. Simultaneously the length adjustable, preferably telescopable cross beam  2   c  slides together. After the desired width of the transport vehicle  1  has been achieved via the aforementioned driving movement, the bolts  14  are put through the respective openings  12  of the hole pattern of the perforated plate  11  and in this way the arms  4   a ,  4   b  and  5   a ,  5   b  and therefore the load carriers  2   a  and  2   b  connected with them are fixed in a defined position in respect to each other. 
         [0029]    The moving apart of the load carriers  2   a  and  2   b  is done correspondingly: After the locking elements of the means  10 , i.e. in this case the bolts  14 , have been removed, the steering axles of the wheel assemblies  6  are positioned in such a way that the dual wheels  3   a —seen in the aforementioned direction of travel—are arranged running spread apart. If now the transport vehicle  1  is moved in said direction, the wheels  3   a  move outwardly, so that the load carriers  2   a  and  2   b  are moved apart from each other. After the desired width has been reached, the bolts  14  are put into the corresponding openings  12  of the hole patterns  11 . In this way a fixation of the scissor links  4  and  5  in respect to their angular position and hence to the distance between the load carriers  2   a  and  2   b  is achieved. 
         [0030]    It is possible too, that the transport vehicle  1  comprises means known to the person skilled in the art and hence not shown, e.g. hydraulic or pneumatic cylinders, which act in traverse direction onto the load carriers  2   a  and  2   b , in order to change the angular position of the arms  4   a ,  4   b  and  5   a ,  5   b  of the two scissor links  4  and  5  and the load carriers  2   a  and  2   b  by these means. 
         [0031]    It is possible to that between the scissor links  4  and  5  a corresponding device  20  is arranged, by which the longitudinal distance between the joints  4   c  and  5   c  of the scissor links  4  and  5  can be changed, thus resulting in an adjustment of the angular positions of the arms  4   a ,  4   b  and  5   a ,  5   b  of the scissor links  4  and  5  and hence of the distance between the two load carriers  2   a  and  2   b . In the second exemplary embodiment shown in  FIGS. 5 and 6  it is provided that this device  20  for changing the longitudinal distance of the joints  4   c  and  5   c  of the scissor links  4  and  5  is a hydraulic operated double-acting cylinder  21 : Through an extension of the piston rod  22  of the double-acting cylinder  21  the joints  4   c  and  5   c  are moved in the longitudinal direction of the transport vehicle  1  apart from each other, so that the load carriers  2   a  and  2   b  are moved apart from each other. In a corresponding manner the retraction of the piston rod  22  of the double-acting cylinder  21  has the effect that the distance between the joints  4   c  and  5   c  decreases, so that the load carriers  2   a  and  2   b  are moved towards each other and in this way the width of the transport vehicle  1  and hence its track width is reduced. It is of advantage if the moving together and moving apart of the load carriers  2   a ,  2   b  is supported by an appropriate positioning of the wheels  3   a  of the wheel assemblies  3 . 
         [0032]    In the above description it was assumed that the chassis  2  of the transport vehicle  1  only has got the two load carriers  2   a  and  2   b  connected by the scissor links  4  and  5 . It is possible too to cascade the previously described arrangement, e.g. that besides the two previously described load carriers  2   a  and  2   b  connected via the scissor links  4  and  5  at least one further load carrier of the chassis  2  is provided, which is once more connected via further scissor links with the load carriers  2   a  and  2   b  respectively. It is possible to provide more than three load carriers  2   a  and  2   b  and to connect adjacent load carriers via scissor links  4  and  5 . 
         [0033]    In the above description, it was assumed that between adjacent load carriers  2   a  and  2   b  two scissor links  4  and  5  are arranged. This is not mandatory, but it is possible only to provide only one scissor link  4  or  5  between the two load carriers  2   a  or  2   b , although this is not preferred. When using long load carriers  2 a and  2   b  it is of advantage to provide more than two scissor links  4  and  5 . 
         [0034]    The provision of the wheel assemblies  3  of the transport vehicle  1  with corresponding steering axles is preferred, since this is a particular simple and elegant way to change the distance between the load carriers  2   a  and  2   b  and hence the width of the transport vehicle  1  via a corresponding driving movement. But this is not mandatory. It is, e.g. possible to apply a force on the scissor links  4  and/or  5  by means of a side impact of one or both load carriers  2   a  and/or  2   b , which results in a change of the angular position of the load arms  4   a ,  4   b  and/or  5   a ,  5   b  and hence a change of the distance between the load carriers  2   a  and  2   b . Here, the dual wheels  3   a  of the wheel assembly  3  are de facto pushed over the ground bearing the transport vehicle  1 . 
         [0035]    In conclusion, it must be stated that by the measures described a transport vehicle  1  is provided, which is characterized by its simple width and hence track width adjustment. By providing that at least two load carriers  2   a ,  2   b  of the chassis  2  of the transport vehicle  1  are connected via one or several scissor links  4 ,  5  with each other, the distance of the corresponding load carriers  2   a  and  2   b  can be increased or reduced by a simple driving movement of the transport vehicle  1  in connection with appropriately build wheel assemblies  3 .