Patent Publication Number: US-9834263-B1

Title: Expanding self propelled modular transport trailers

Description:
FIELD OF THE INVENTION 
     This invention relates generally to apparatus and methods for heavy-load transport trailers, especially self-propelled modular transport (“SPMT”) trailers. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the invention, its background is described in connection with existing self-propelled modular transporters (“SPMT”) for transport of very heavy and large loads weighing tens to hundreds of tons. SPMTs are a combination of a trailer unit and a power pack unit (“PPU”). In simplest form, the trailer unit includes two longitudinal rows of paired wheels such that viewed from the top there would be 4 longitudinal lines of wheels, two on one side and two on the other side. Each wheel pair has its own axle. Viewed from the side, there will typically there will be 3, 4, 5, 6 or 8 axle assemblies visible representing half of each cross-wise matching set for a total of (respectively) 12, 16, 20, 24 or 32 wheels per module depending on the number of axle assemblies. Each axle of a given wheel pair can swivel independently of the other wheel pairs and some or all of the wheels are individually controlled and hydraulically propelled. Each wheel assembly communicates with a controller that commands the wheel assembly to turn, brake or rotate. Electronic control of the wheel assemblies allows for synchronous steering with unitary control of the wheel assemblies. The wheel assemblies can also be raised and lowered hydraulically to adjust the vertical height of the deck and can move up and down independently to allow movement over uneven surfaces without up and down movement of the upper load carrying deck. 
     Typically, SPMTs are constructed with a single deck having two longitudinal lines of wheel pairs mounted underneath. Such an arrangement would be considered a double axle trailer or one line. Alternatively, a given longitudinal string of single axle wheel pairs may have its own deck such that in use two long single axle wheel-pair trailers would be bolted together to form a unitary deck. Because the trailers are modular, they are strung together end-to-end to increase the overall length of the combined modules. 
     Typically, when widthwise extension of the trailer platform is required for very wide loads, a series of trailers will be run together side-by-side as shown in  FIG. 1B . Flexibility of the width of combined trailers has been obtained with combinations such as for example a triple axle arrangement with a double axle trailer combined with a single axle trailer to form three longitudinal lines of wheel pair assemblies with 6 wheels across in three pairs. 
     However, such a parallel arrangement consumes a large number of trailers. More recently, split trailers have been developed in which two single axle wheel-pair trailers are separated by telescopic bars that connect the trailers. Problematically, the telescopic bars prevent the two trailers from coming close together and/or project from the sides of the trailers. 
     Provided herein are novel extension mechanisms to provide variable extension widths of SPMT trailers while providing the required stability of a unitary structure. 
     BRIEF SUMMARY OF THE INVENTION 
     Disclosed herein are folding widening assemblies that connect between two longitudinal multi-axle wheel frames. In one embodiment, a pair of longitudinal multi-axle wheel frames are connected by at least three widening assemblies, each of the widening assemblies including a pair of hinged opposing folding arms connecting the longitudinal multi-axle wheel frames. At least one of the widening assemblies will be a motive assembly that by folding or opening acts to diminish or extend the distance between the longitudinal multi-axle wheel frames. 
     In one embodiment a split variable extension width self-propelled motorized transporter (SPMT) vehicle is provided that includes a pair of matching longitudinal chassis, each chassis including a deck supported by a plurality of wheel pair assemblies, and at least three widening assemblies mounted between the two chassis, wherein each of the widening assemblies comprises a pair of hinged opposing folding arms, each of the pair of folding arms pivotably connecting the two matching longitudinal chassis through a center hinge that is affixed to a central aligner that runs longitudinally between, and equidistant from, each of the longitudinal chassis. In certain embodiments at least two of the widening assemblies operate as a passive pair, having arms that move in the same direction and central hinges that are affixed in a set location on the central aligner, and the third widening assembly is a sliding assembly having widening arms that move in an opposite direction to the passive pair and having its center hinge affixed in a slidable position on the central aligner such that movement of the two longitudinal chassis toward or away from each other moves the hinge of the sliding widening assembly relative to the fixed positions of the central hinges of the passive pair and assists in stable widening or narrowing of a distance between the longitudinal chassis. 
     In certain embodiments, the center hinge of the sliding assembly is affixed on a runner that slides along the central aligner. Desired positions of the runner on the central aligner may be set by a pin or bolt that locks the runner in a fixed location on the central aligner. The central aligner can be a tube, rod or beam and the runner will be configured to fit around and slide over the central aligner. 
     In certain embodiments, the central aligner is a hydraulic cylinder and the center hinges of the passive pair of widening assemblies are affixed in a set location to a housing of the hydraulic cylinder and the center hinge of the sliding assembly is affixed to a piston rod of the hydraulic cylinder such that movement of the piston rod moves the hinge of the sliding widening assembly relative to the fixed positions of the central hinges of the passive pair. Stabilizing lines such as chains or cables may be affixed between at the passive arm chassis connections of at least one widening assembly and a central hinge of an adjacent widening assembly. In certain embodiments the central hydraulic cylinder is powered by a Power Pack Unit that also provides hydraulic power to the wheel assemblies. 
     In other embodiments, additional passive widening assembly are provides to enable further length of the trailers and further stability. In some embodiments, a dual hydraulic cylinder is provided having a first and second piston, the first and second pistons adapted to move in opposite directions relative to each other and a fourth sliding widening assembly positioned behind the pair of passive widening assemblies and having a central hinge affixed to the second piston and its widening arms moving in the same direction as the arms of the passive pair. 
     In certain embodiments, the arms of the widening assemblies include pairs of hinged opposing folding arms that include a set of two hinged top arm pairs and two hinged bottom arm pairs pivotably attached to and sandwiching the central aligner or hydraulic cylinder. 
     In other embodiments, a split variable extension width self-propelled motorized transporter (SPMT) vehicle is provided that includes a pair of matching longitudinal chassis, each chassis including a deck supported by a plurality of wheel pair assemblies and at least three widening assemblies mounted between the two chassis, wherein each of the widening assemblies comprises a pair of hinged opposing folding arms, each of the pair of folding arms pivotably connecting the two matching longitudinal chassis through a center hinge that is affixed to a central aligner that runs longitudinally between, and equidistant from, each of the longitudinal chassis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, including features and advantages, reference is now made to the detailed description of the invention along with the accompanying figures: 
         FIG. 1A  depicts a typical prior art SPMT single module, which includes a power pack unit (“PPU”) and a trailer unit having two longitudinal columns, each column having a plurality of single axle wheelset assemblies.  FIG. 1B , depicts a typical prior art SPMT having eight trailer assemblies bolted together and operated by two PPU. 
         FIG. 2A  depicts one embodiment of a split SPMT having three hinged widening assemblies per module in a closed position.  FIG. 2B  depicts the split SPMT of  FIG. 2A  in an expanded position.  FIG. 2C  illustrates the angles formed by the hinged arms of the embodiments of  FIGS. 2A  and B relative to a central hydraulic cylinder. 
         FIG. 2D  depicts an embodiment wherein the motive widening assembly includes a sliding ring over a central aligner. 
         FIGS. 3A and 3B  depict an alternative embodiment having 4 hinged widening assemblies. In  FIG. 3A  the split SPMT is in a collapsed position while in  FIG. 3B  the split SPMT is in an expanded position. 
         FIG. 4  illustrates an oblique end on view of one embodiment showing the relative attachment positions of the hinged arms to the trailer chassis and a central aligner or hydraulic cylinder. 
         FIG. 5  illustrates another oblique end on view of one embodiment showing the relative attachment positions of the hinged arms of the widening assemblies to the trailer chassis and a central aligner or hydraulic cylinder. 
         FIGS. 6A-C  show end on views of an embodiment of a split SPMT in collapsed ( FIG. 6A ), partially extended ( FIG. 6B ) and fully extended positions ( FIG. 6C ). 
         FIG. 7  represents an embodiment of a hydraulic system schematic for operating a motive force piston rod to expand or collapse a split SPMT. 
         FIG. 8A  shows a prior art single module SPMT relative to a split SPMT according to an embodiment of the invention depicted in  FIG. 8B . 
         FIG. 9A  shows the end to end connection of two split SPMTs thus providing a 24 axle split SPMT. The circled elements represent a shared hydraulic.  FIG. 9A  depicts an embodiment having three hydraulic systems and what could be termed a three hydraulic suspension.  FIG. 9B  depicts an embodiment having four hydraulic systems and what could be termed a four hydraulic suspension.  FIG. 9C  provides a side view of the embodiments of  FIGS. 9A  and B. 
         FIG. 10A  demonstrates a prior art multiple module SPMT while  FIG. 10B  shows a calculated angle to a center of gravity (COG) for the trailer of  FIG. 10A  with an assumed weight and COG height.  FIG. 10C  demonstrates a multiple module split SPMT according to one embodiment while  FIG. 10D  shows a calculated angle to a center of gravity (COG) for the trailer of  FIG. 10C  using the same criteria as  FIG. 10B . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that may be employed in a wide variety of specific contexts. The specific embodiment discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. 
     In heavy transport, high and wide loads with a high center-of-gravity—such as large pipe rack modules—are typically transported on multiple rows of SPMTs. Connecting more SPMT trailer units side-by-side creates a wider loading platform ensuring stability of the load during transport and enhancing safety. However, in many cases the increased load capacity that comes with the additional trailer units is not required. What is instead required is a wider bed. Provided herein is a SPMT including widening assemblies that allow for variable spacing of split SPMT trailers—increasing the width of the loading platform without the need to add more SPMTs and Power Pack Units (PPUs). This allows for safer and more cost-effective transport of specific loads and reduces the carbon footprint of those transports that would otherwise need more SPMTs and PPUs. 
     In one embodiment provided herein is split SPMT is described that includes at least three widening assemblies, each assembly comprising a pair of articulated arms that are outwardly attached to the inner walls of two SPMT single chassis and are centrally connected to a central aligner running centrally and longitudinally between the two chassis. Through the use of at least three widening assemblies, the two longitudinal chassis are kept in parallel. In one embodiment the central aligner is a hydraulic cylinder. In such embodiments, the hydraulic cylinder helps provide a motive force that works with the motorized wheel assemblies of the chassis to assist in moving the longitudinal chassis together and apart. In other embodiments the central aligner is passive and for the motive widening assembly, its articulated arms are centrally connected to a runner that slides over the central aligner. In such embodiments, motorized wheel assemblies of the chassis drive the chassis together or apart. In either event, the central aligner, whether passive or hydraulic keeps the articulated arms aligned as they move to either increase or decrease the distance between the trailer chassis. 
     In certain embodiments, the split SPMT with widening adaptor has a minimum width of 3 meters and a maximum width of 6.4 meters—meaning one row of split SPMTs can replace two rows of conventional SPMTs. 
     In certain embodiments, the widening assemblies are removable for shipment. If removed and placed on top of the two reconnected SPMT-halves, the width is reduced to 2.43 meters making it possible to fit the split SPMT into a standard flat rack shipping container for efficient shipping. 
       FIG. 1A  depicts a typical prior art SPMT single module  10 , which includes a power pack unit (“PPU”)  12  and a trailer unit  14  having two longitudinal columns, each column having a plurality of single axle wheelset assemblies  18 . The dark loops  16  represent coupled hydraulics for this embodiment bearing in mind that this may be different for every combination. Each pair of wheels is fixed to its own axle forming a wheelset  18  that can rotate through certain degrees of rotation and then turn around and cover other degrees of rotation going “backwards.” Each wheelset can be driven in any direction. Typically the wheelsets will be affixed to an upper rigid deck (not shown). Currently when SPMTs are utilized for wide loads one option is to double the number of trailer assemblies widthwise as shown in  FIG. 1B . In the example of  FIG. 1B , eight trailer assemblies  14  are bolted together and are operated by two PPU  12 . Problematically in this implementation, the entire unit is extremely heavy and the overall width is not negotiable. It is either a single wide or is double the width of the single wide. 
     Provided herein is a solution that enables a variable width split trailer SPMT that has the required dimensional stability to keep the two single trailers parallel to each other at all times. As depicted in one embodiment in  FIG. 2B , two single axle trailers  20  (here termed as “single axle” because there is one widthwise axle per trailer chassis although in the depicted embodiment there are six single axles along a longitudinal aspect of each single trailer) are separated by at least three widening assemblies  22 ,  24  and  26  that each include an “elbow” hinged articulated arm set. Each arm set will have a right arm and a left arm of the same length connected by a central pinned hinge. Each left arm of each hinged arm set will be connected on an outer end (that is—distal to the central hinge) to an inner aspect of a left or port trailer chassis by a pivot bracket. Conversely, each right arm of each hinged arm set will be connected on an outer end to an inner aspect of a right or starboard trailer chassis by a pivot bracket. Thus, in the depicted embodiment, hinged left arm  26   a  is fixed on an innermost end to central hydraulic cylinder housing  30  via a central pinned hinge  34  that also connects to innermost end of hinged right arm  26   b . Hinged left arm  26   a  is connected on an outermost aspect to left or port chassis  48  via a pivot bracket  28 . Likewise, hinged right arm  26   b  is connected on an outermost aspect to right or starboard chassis  46  via a pivot bracket  28 . 
     Similarly, hinged arm set  24  is affixed to central hydraulic cylinder housing  30  via a central pinned hinge  36 . In the depicted embodiment, arms  26   a,b  and  24   a,b  are passive and affixed to the central hydraulic cylinder housing at a fixed longitudinal position relative to each other. In the depicted embodiment of  FIGS. 2A  and B, hinged arm set  22   a,b  is the motive widening assembly and its arms are fixed on an outer end of central hydraulic cylinder piston rod  38  via pinned hinge  32 . Whether passive or motive, the outer ends of each arm set are connected to their respective chassis via pivot brackets  28 . 
     While  FIG. 2B  depicts the two chassis  20  in a separated position,  FIG. 2A  depicts the two chassis  20  in their closest opposition with the plurality of widening assemblies (arm sets)  22 ,  24  and  26  folded against the central hydraulic cylinder  30 . In the fully closed position, piston rod  38  of the hydraulic cylinder is fully extended. In a widening operation, each wheel assembly (one of which is shown within dashed circle  18 ) of both trailer chassis will be turned 90° outward respective to a forward position toward the PPU. The wheel assemblies can be driven apart and the arms would begin to unfold if hydraulic pressure was relieved from the hydraulic cylinder such that the piston rod could retract into the cylinder. However, in practice, in order to achieve full extension the motive force of the central hydraulic cylinder is employed because full extension is difficult to achieve in an unloaded trailer. In some cases, in the absence of weight on the trailer, the wheels may be unable to be sufficiently anchored by weight to achieve full extension but may spin on the ground surface. Thus, the motive power of the central hydraulic cylinder is utilized to achieve full extension. In an opening operation, hydraulic fluid is pumped into hydraulic port  52 , which will act to push piston rod  38  inward through hydraulic cylinder housing  30 . As piston rod  38  is pushed longitudinally inward, it will carry affixed hinge  32  inward. 
     Because the hinge  36  of the next pair of arms is fixed on the housing of the hydraulic cylinder, as piston rod  38  is pulled in, the two hinges  36  and  32  will be drawn longitudinally together thus causing their respective arms to extend. Because the next widening assembly, arm set  26 , is in a fixed position nested behind the central widening assembly, arm set  24 , on the central cylinder, with its arms parallel to the arms of the adjacent arm set  24 , its arms will be passively extended at the same angle as those of set  24 . At all times except when fully folded, the arms of the nested set of hinged arms when considered together with the chassis and the central cylinder will together form a parallelogram shape  42  on each side of the central cylinder. As opposed to a design having only two sets of arms, the further set of nested arms provides that the two trailers will have a stable parallel relationship to each other. The action of the hydraulic cylinder acts to keep a desired distance between the trailer chassis and further dimensional stability can be provided with chain or cable  60  that fixes an outward distance between the pivot bracket of arm  26   a  and central hinge  36  once a desired distance between the trailer chassis is obtained. 
       FIG. 2B  also shows a flexible hydraulic line track  44  that extends or retracts depending on the distance between the trailers. In the embodiment depicted in  FIGS. 2B  and C, the hinged arms of motive widening assembly (arm set  22   a, b ) oppose the arms of the next adjacent passive widening assembly (arm set  24   a, b ) to form a generally diamond shaped space between them. Thus, while one arm of set  22  will be at an angle X to central cylinder  30 , the respective opposing arm of set  24  will be at the same angle inverted to the central cylinder (360°−X in a full 360° plan). The system of the embodiment depicted in  FIG. 2C  includes 3 pivoting widening assemblies each comprising a pair of articulated arms (arm sets), a sliding lead widening assembly including sliding arms  22   a  and  22   b , a middle widening assembly including passive arms  24   a  and  24   b  and a tail widening assembly including passive arms  26   a  and  26   b . The lead widening assembly and the middle widening assembly oppose each other forming a diamond shape between then, while the tail widening assembly is nested behind the middle widening assembly with its arms in a parallel relationship to the arms of the middle widening assembly. The lead widening assembly arms  22   a  and  22   b  of the diamond shaped group of two widening assemblies are motive arms affixed in the central hinge to an outer aspect of a piston rod  38 . The arms of the following middle widening assembly are affixed to the hydraulic cylinder housing from which the piston rod extends so the shape of narrow or wide diamond is formed by the inner and outward movement of the piston rod. As the piston rod is pushed out hydraulically, the arms of the lead widening assembly pivot backwards from the arms of the following middle widening assembly. The middle arm set  24   a, b  and the tail arm set  26   a, b  are affixed to the central cylinder  30  and will always pivot at the same angle thus forming parallelograms shapes on each side of the central cylinder. Whether the motive lead arms are extended or collapsed, the tail arm set will keep the trailer chassis in a parallel relationship. 
       FIG. 2D  depicts an embodiment of a split variable extension width SPMT vehicle having a pair of matching longitudinal chassis  48 , each chassis including a deck supported by a plurality of independently swiveling wheel pair assemblies  18 . In this embodiment, a set of at least three widening assemblies are provided, wherein each of the widening assemblies comprises a pair of hinged opposing folding arms ( 26   a  and  26   b ,  24   a  and  24   b , and  22   a  and  22   b ), each of the pair of folding arms pivotably connecting the two matching longitudinal chassis through a center hinge ( 34 ,  36  and  32  respectively) that is affixed to a central aligner  31  that runs longitudinally between, and equidistant from, each of the longitudinal chassis, wherein at least two of the widening assemblies operate as a passive pair ( 26   a ,  26   b  and  24   a ,  24   b  in the example shown), having arms that move in the same direction and central hinges that are affixed in a set location relative to each other on the central aligner  31 , and wherein the third widening assembly is a sliding assembly having widening arms  22   a  and  22   b  that move in an opposite direction to the passive pair and having its center hinge  32  affixed to runner  33  that is movable along the central aligner such that movement of the two longitudinal chassis away or toward each other moves the hinge of the sliding widening assembly relative to the fixed positions of the central hinges of the passive pair and assists in stable widening or narrowing of a distance between the longitudinal chassis. In certain embodiments runner  33  is a circumferential member such as a ring if the central aligner is tubular or may have a square or rectangular configuration if the central aligner is an angular beam. In other embodiments, the runner moves in a track in the central aligner. When a desired width between the two chassis is reached, the position of runner  33  is fixed. In one embodiment the position of runner  33  is fixed by pins or bolts  37  that pass through the runner and the central aligner such as with holes  35  through the central aligner. In embodiments such as this without a central hydraulic cylinder, if the wheel assemblies are not able to fully expand or retract the folding arms, the chassis can be pushed together or pulled apart by any number of devices including, without limitation, tractors, come-alongs or portable hydraulics. 
       FIGS. 3A  and B depict an alternative embodiment with four sets of arms, the last three of which are nested and fold in the same direction forming matching parallelograms between them on each side of the central hydraulic cylinder (as shown with the doted line), while the first arm set folds in an opposite direction thus forming a diamond shape respective to the first of the nesting set of arms. The final three arm sets may be passive. Alternatively, in embodiment such as is depicted in  FIG. 3B  a double hydraulic cylinder maybe utilized with two piston rods  38  and  39  moving in opposite directions into and out of central housing  30 . As shown in  FIG. 3B , the hinged arms of sliding arm set  22   a, b  oppose the arms of passive arm set  24   a, b  to form a generally diamond shaped space between them. The system of the embodiment depicted in  FIG. 3B  includes 4 pivoting sets of arms, a sliding lead set including sliding arms  22   a  and  22   b , a middle set including passive arms  24   a  and  24   b  and a two tail sets including passive arms  26   a  and  26   b  and either motive or passive arms  27   a  and  27   b . The lead set and the following middle set oppose each other forming a diamond shape, while the tail sets are nested behind the middle set with their arms in a parallel relationship to the arms of the middle set. The lead arms of the diamond shaped group of two arm sets are motive arms affixed in the middle hinge to an outer aspect of piston rod  38 . The following middle arms of the diamond shaped pair are affixed to the hydraulic cylinder housing  30  from which the piston rod extends so the shape of the diamond is formed by the inner and outward movement of the piston rod. As the piston rod is pushed out hydraulically, the lead arms pivot backwards from the following middle arms. The middle arm set  24   a, b  and the tail arm sets  26   a, b  and  27   a,b  will always pivot at the same angle thus forming parallelogram shapes shown in the dashed lines. Whether the motive lead arms are extended or collapsed, the tail arm sets will keep the two trailer chassis in a parallel relationship. 
       FIG. 4  depicts a partial oblique end on view of one embodiment of a mechanism of fixation of the hinged arms of the widening assemblies to the central cylinder, rod or beam  30 . Each arm is actually a pair of arms, a top arm  61  centrally affixed on top of the central cylinder, rod or beam  30  by a hinge  34 , and a matching bottom arm  62  centrally affixed on a bottom of the central cylinder, rod or beam  30  by a hinge (not shown). Each of the top and bottom arms of the passive arms are affixed to the central cylinder, while the top and bottom arms of the motive arms are affixed to the distal end of the piston rod or sliding runner (not shown). Each set of top and bottom arms are attached to the inner side of the chassis  48  by pivot bracket  28 . 
       FIG. 5  depicts another partial oblique end on view of hinged arms  61  and  62  affixed via a pinned hinge  34  to the top and bottom of central hydraulic cylinder housing  30 . Hydraulic lines  70  provide motive force to the hydraulic cylinder. Hinged arms  61  and  62  are affixed to chassis  48  via pivot bracket  28 . 
       FIGS. 6A , B and C depict end on views of an embodiment of the invention and show the widths of the outer aspects of wheel assemblies.  FIG. 6B  depicts an end on view of hinged arms  61  and  62  affixed via a pinned hinge  34  to the top and bottom of central hydraulic cylinder housing  30 . Hinged arms  61  and  62  are affixed to chassis  48  via pivot bracket  28 . Load deck  70  stretches across the two single axle trailers. As shown in the embodiment depicted in  FIG. 6A , the width to the outer aspect of the wheel assemblies when the hinged arms are completely folded on the central cylinder would be about 9 ft., 10 inches. When in one partially extended example as shown in  FIG. 6B , the width to the outer aspect of wheel assemblies  18  would be 17 feet 5¾ inches. When fully extended as shown in  FIG. 6C , the width to the outer aspect of the wheel assemblies would be 21 feet. Thus, the trailer wheel assemblies can be placed at any width between about 9 ft., 10 inches and 21 ft permitting a desired accommodation not only to the load requirement but also to available roads on which the trailers must move. 
       FIG. 7  shows one embodiment of a hydraulic system for providing the motive force to extend or collapse the arms of a hinged arm split trailer SPMT. Piston rod  38  moves back and forth within hydraulic cylinder housing  30  as hydraulic fluid is pumped in or out of the two sides of the cylinder via ports  50  and  52 . Hydraulic lines  70  and  71  are connected via a plurality of pressure relieve valve systems  74 , which may include an accumulator  76  that provides safety compensation for temperature changes that may affect the volume of the hydraulic fluids. Hydraulic lines are preferably provided with quick connects  78 . Preferably, quick connects are used to connect the hydraulic hoses of the frame to hydraulic valves built into the wheel assemblies. 
     In one embodiment, the hydraulic pressure of the wheel assembly drive system is activated to push out or pull in the piston rod of the central hydraulic cylinder at the same time as the axles are pressurized to drive the trailers open or closed. In other embodiments, the drive system is not used and the hydraulic pressure of the steering system is used to open and closed the trailer using steering pressure. 
       FIG. 8A  depicts the width of a prior art SPMT having two longitudinal lines of single axle wheel assemblies that would be affixed to a single top deck (not shown). In contrast,  FIG. 8B  depicts the width obtainable through a widthwise extension of an embodiment including one PPU  12  and two single axle trailers  20  that are split by at least three hinged hydraulically operated arms. 
       FIG. 9A  depicts an embodiment that combines 2 modules, each of which includes two single axle  6  wheel assembly trailers  20  that are each split by at least three hinged hydraulically operated arms. The looped circles show that three hydraulic groups ( 16   a ,  16   b  and  16   c ) are utilized, however, this grouping is flexible and can also be changed to match each special loading condition put onto the trailer.  FIG. 9B  depicts an embodiment having four hydraulic systems ( 16   a ,  16   b ,  16   c  and  16   d ) and would be termed a four hydraulic suspension system.  FIG. 9C  provides a side view of  FIGS. 9A and 9B . 
       FIG. 10A  depicts the width of a prior art SPMT having two longitudinal lines of single axle wheel assemblies that combines 4 modules end to end. As shown in  FIG. 10B , in this example the combined width to the outside of the wheels is 7 feet, 11¾ inches. The advantage of the split version is shown by comparing  FIGS. 10B and 10D . By an assumed same stability angle of 7.2 degrees and same weight of cargo, the maximum height of the COG of the load that can safely be transported without causing the trailer to capsize is 9 feet above the deck of the trailer shown in  FIG. 10B . In contrast, when using the split SPMT shown in  FIG. 10C , showing 4 modular sets of split SPMT, with a width to the outside of the wheels of 17 feet, 5¾ inches,  FIG. 10D  shows that the maximum height of the COG above the trailer deck is ˜27 feet with an even better stability angle of 8.8°. Using 4 points will increase the stability angle even more.