Abstract:
A removable and raisable roof attached to four upright supports is mounted on an open bed trailer. Two supports are located on the left and right corners of the forward edge of the trailer; the other two supports are similarly located at the rear corners of the trailer. No side supports are necessary. Using elevating means within the supports, which can operate independently or in tandem, the front and/or rear portions of the roof can be raised and lowered separately. Using external attachable fixtures and ground mounted supports, each of the roof supports can be lifted from their mounted position on the trailer bed and the trailer driven out from under the supports and roof assembly, converting a covered van to a fully open van. If a fully enclosed trailer is desired, then tarpaulin, or other readily removable wall materials can be suspended from the roof and attached to the trailer bed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an enclosure for the trailer portion of a flatbed of a truck, trailer or any other vehicle such as a railroad car. In particular, the present invention relates to an enclosure with a readily adjustable height, minimal reduction of the loading width or length of the trailer and the ability to be readily and easily removed to leave an open bed trailer. 
     AREA OF THE ART 
     Vehicles used to transport freight may be either open or closed bed. Open bed vehicles, commonly referred to as flatbed vehicles offer the advantage of accommodating a variety of loads and are generally less expensive to produce. Further, the load on the trailer can be accessed from the sides and above as well as from the rear of the vehicle. However, these trailers have a disadvantage in that the load is open to the environment and can be damaged in transit or readily pilfered. Further, since the load is open, often it can only be transported during clear weather. Placing a tarp over the load to protect it from the environment is often not possible because the load is crushable and can not be walked on to place or remove the tarp. Also operators are often injured due to falls while placing the tarp. 
     An advantage of a closed trailer is the protection and security provided for the load. However, the presence of the enclosure and a fixed height roof on the trailer limits access to the load, makes loading of the trailer more difficult, and results in less usable space for the same size trailer bed width and limits the use of forklifts to load the trailer as the trailer roof interferes with the ability of the forklift operator to adequately lift the load. Further, the mere presence of the walls and roof of the enclosure limits the ability to utilize the full internal width and height of the enclosed trailer without hand stacking. Still further, even though some trailers are stacked by hand to fill the maximum height, it is virtually impossible to take advantage of the maximum allowable 14 foot height with most trailers having a fixed height of 13.5 ft. 
     In addition, in order to accommodate all types of freight, a carrier must maintain an inventory of both open and closed trailers, thus doubling the inventory of vehicles he must have access to. 
     The present invention addresses the disadvantages of these different load carriers while retaining the advantages of both the open and closed trailers. 
     DESCRIPTION OF THE PRIOR ART 
     Often it is desirable to load a trailer with bulky cargo. Current closed trailers must, of course, be loaded from the rear end of the trailer. Due to the internal height restrictions, the use of a forklift is restricted. In any event, using a forklift it is impossible to fill the entire internal height of the trailer and or to load the cargo to fill the full internal width of the closed trailer without hand stacking. Additionally, the presence of the walls takes up space that could be used for cargo if the walls did not exist. Therefore, it is often desirable, to make best use of space available, to use an open (flatbed) trailer. While highway truckers are limited to the 14 foot height restriction, an open trailer allows the entire width and length of the trailer to be used and provides the opportunity for the cargo to be loaded from the rear as well as from either side to the full 14 foot height. However, this also provides the opportunity for the height of the loaded trailer to exceed the highway 14 foot height restrictions, leaves the cargo open to the elements and subjects the cargo to pilferage and loss during transportation unless covered by a tarpaulin. While this may be alleviated to some extent by covering the load with a tarpaulin cover, the covering process is time consuming, often does not provide the protection desired and creates risk of the driver falling and being injured during placement of the tarpaulin. Further, many soft loads, i.e., food stuff, packaged goods, etc., can not be covered because the weight of the tarpaulin, or the operator walking on the load to place the tarpaulin, can crush and damage the load. 
     The use of trailer enclosures that are adjustable in height are known. The patent art describes various different designs intended to give this flexibility. For example, U.S. Pat. No. 4,103,958 to Parent describes a bus body of typical construction having fixed side walls defining a lower floor. Mounted thereon is a roof which can be raised to create a second floor passenger area. The movement of the roof is controlled by two pair of interconnected hydraulic cylinders mounted within the fixed walls. 
     U.S. Pat. No. 4,206,943 to Friedenberg and U.S. Pat. No. 4,392,682 to Norkus both show a lower fixed inner wall and a moveable outer wall. Friedenberg shows guide rods mounted between the inner and outer wall to guide the vertical movement of the outer wall following activation of screw jacks. Norkus has rods on beveled gears, all of which are interconnected, to raise the roof. This construction, while it functions to raise the roof uniformly, significantly reduces the available width of the trailer. Norkus also does not provide the ability for the roof lifting procedure to be provided, alternatively, from either side of the vehicle or to lift only the front or rear roof edge. 
     U.S. Pat. No. 4,603,901 to Mcintosh shows a conventional pickup truck with an open bed. Jacks are placed in the side walls and a raisable roof is attached to the jacks. 
     The Dowty U.S. Pat. No. 4,887,860 shows a typical closed trailer construction with ribbed, vertical walls enclosing a series of hollow spaces which include hydraulic or electric jacks to raise or lower the roof. 
     U.S. Pat. No. 5,114,202 to Johnson is directed to a closed wall trailer that has jacks mounted in the four interior corners to support and raise or lower a moveable roof. 
     All of the above patents are directed to systems for raising the roof of a closed vehicle in a uniform manner. In all instances the trailer has a fixed lower wall and, in several instances, as a result of the mechanical design, the internal trailer space is narrowed and shortened, reducing the available storage space. Further, all of these designs are permanently installed on to the trailer, are subject to mechanical problems and do not provide the capability of removing the structure to provide an open trailer. Still further, none of these references provides the capability of independent adjusting the height of the front or rear of the trailer so that the height of the roof, even on a sloped trailer, can be 14 foot along the whole trailer length. 
     Therefore, there is a need for a trailer enclosure which allows the full width and length of the trailer bed to be filled with cargo, allows loading of the cargo from all sides, allows the loading of the cargo to not be restricted by a fixed height roof and provides the capability for cargo to be readily covered and secured without damaging the cargo. Further, it is desirable to provide a roof which can be lifted from either side of the trailer and an enclosure which can be readily removed so that the benefits of an open trailer can be utilized if the cargo is amenable to being carried on an open trailer. 
     SUMMARY OF THE INVENTION 
     The invention comprises a panel roof supported by four upright supports for removably mounting on an open bed trailer. Two upright supports are located on the left and right corners (the driver side and passenger side) of the forward edge of the trailer; the other two jacks are similarly located at the rear corners of the trailer. No side walls or end walls are necessary, but may be included if desired. Also, side supports along the length of the trailer are not necessarily required. However, two movable and removable side supports typically are used with the disclosed embodiments in a 50 foot span and one support is used in a 25 to 30 foot span. Using elevating means within the upright supports, which can operate independently or in tandem, the front and/or rear portions of the roof can be raised and lowered separately. Further, using external attachable fixtures and ground mounted supports, each of the upright supports can be lifted from its mounted position on the trailer bed and the trailer driven out from under the removable enclosure or the roof structure rolled off the trailer bed, converting a covered van to a fully open flatbed trailer. While a fully enclosed trailer is desired, moveable tarpaulin, or other readily removable wall materials can be suspended from the roof and attached to the trailer bed or the sides can be left open and front and rear wall panels can be hinged from the upright supports or hung from the roof front and rear rails. 
    
    
     DESCRIPTION OF THE FIGURES 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where: 
     FIG. 1 is a perspective side view of a removable, expandable trailer top embodying features of the invention mounted on a trailer. 
     FIG. 2 is a side view of the upper portion of the removable trailer top embodying features of the invention. 
     FIG. 3 is a view of the rear end of the upper portion of the removable trailer top embodying features of the invention. 
     FIG. 4 is a front view of the front end upper portion of the of the removable trailer top embodying features of the invention. 
     FIG. 5 is a view of the top of the removable trailer top embodying features of the invention. 
     FIG. 6 is a side view of the lower portion of one of the upright supports of the removable trailer top shown in FIG.  2 . 
     FIG. 7 is a front view of the lower portion of the upright support show in FIG.  6 . 
     FIG. 8 is an enlarged front view of the ratchet extension arm. 
     FIG. 9 is a partially cut away schematic view of a first version of the internal drive structure in the front end or the rear end of the removable expandable trailer top. 
     FIGS. 10 a - 10   e  are partially cut away views of four different drive mechanisms for raising the upright with rack as shown in FIG.  8 . 
     FIG. 11 is a schematic cut away view, broken into several sections, of a second version of an internal drive structure in the front or the rear end of the removable expandable trailer top. 
     FIG. 12 is a front view of a lifting fixture attached to one of the upright supports. 
     FIG. 13 is a side view of the lifting fixture of FIG. 12 attached to one of the upright supports. 
     FIG. 14 is a front view of a wheeled base for use with the lifting fixture of FIGS. 12-13 in removal of the expandable trailer top from a trailer. 
     FIG. 15 is a side view of the wheeled base of FIG.  14 . 
     FIG. 16 is a side view of the expandable trailer top of FIG. 2 mounted on the wheeled base of FIG. 14 following removal from a trailer. 
     FIG. 17 is a partial side view of the expandable joint between an upright support and the roof. 
     FIG. 18 is a side view of the upper portion of the side support. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A removable, expandable trailer enclosure  10  embodying features of the invention is shown in FIGS. 1-18, FIG. 1 showing the trailer enclosure  10  mounted on an open trailer  12 . The expandable trailer enclosure  10  comprises four extendable upright supports, consisting of two driver side supports  14  and two passenger side supports  16 , which may be the same or different as discussed below, and a roof  18  resting on upper telescoping portions  15  within the upright supports  14 ,  16  in a manner that allows the distance between the roof  18  and the trailer bed  20  to be readily increased or decreased as desired. The lower end of the lower portion  17  of the side supports  14 ,  16  have means  224  thereon to allow those side supports to be removably attached to the edge of the trailer bed  20 . The telescoping upper portions  15  in the upper ends of the rear driver side upright support  14  and the rear passenger upright support  16  are connected by a rear cross arm  32 , best shown in FIG. 3, the two rear upright supports and rear cross arm constituting the rear support assembly  36 . Likewise, the upper ends of the telescoping portions within the forward driver side upright support  14  and the forward passenger upright support  16  are connected by a forward or front cross arm  34 , best shown in FIG. 4, the two forward upright supports and forward cross arm constituting the forward support assembly  38 . 
     FIG. 2 is a driver side view of the removable, expandable trailer enclosure  10  showing the two driver side upright supports  14  and the driver side edge  24  of the roof  18 . However, the passenger side view is identical. 
     The roof  18 , shown in FIG. 5, comprises a rectangular frame with support beams  40  running along driver side edge  24  and passenger side edge  42  and a series of cross supports  44  to support a roof. The roof can be composed of any desired material, including tarpaulin, metals, such as aluminum or steel, fiberglass composites, including light transmitting materials so the interior of the trailer isn&#39;t dark, or other common trailer enclosure materials. In the construction shown in FIG. 5, the roof material is not applied. However, it can be panels or a continuous cover such as 8 ft. wide, trailer length, clear fiberglass, aluminum or tarpaulin cover rolled onto the top. The roof is generally supported by only the four upright supports  14 ,  16  which are located at opposite ends of the trailer enclosure. Therefore, the support beams  40  should have sufficient structural strength to span the distance between the front and rear supports  14 ,  16  without an unacceptable sag along the length of the trailer. However, removable uprights, not shown, can be placed along the length to provide additional support. 
     Each of the upright supports  14 ,  16  has a hollow lower portion  17  and contains therein a telescoping upper portion  15  and a lifting mechanism which functions to raise the roof  18  attached thereto. FIGS. 6 and 7 are side and front views, respectively, of the lower portion of the side supports  14 ,  16 . FIGS. 3 and 4 show rear and front views respectively of the upper portion  15  of the driver side upright supports  14 . FIGS. 6 and 7 are representative of the lower portion  17  of the uprights which enclose the lower end of the telescoping upper portions  15 . The supports  14 ,  16  shown in FIGS. 3 and 4 differ in that only the driver side supports  14  in FIG. 3 it is shown to have an extension  48  on its lower end for attachment of a rack  52 . The passenger side uprights  16  may also have the extensions  48  attached thereto. For clarity, FIG. 3 shows the extension  48  without the rack  52  attached and FIG. 4 shows the additional piece  49  with rack  52  attached to the attachment  48  on the passenger side. FIG. 8 is an enlarged view of the additional piece  44  with rack  52  and FIG. 18 is an enlarged view of the upper portion  15 . The holes  53  allow for attachment of the additional piece  49  to the extension  48  on the upper portion  15 . A longitudinal slot through the wall of the upper portion  15 , shown in FIG. 18, receives a bolt or pin  104  mounted in the top end of the lower portion  17 , best shown in FIG. 9, to prevent the upper portion from being raised or lowered too far. 
     Each upright support  14 ,  16  encloses a lifting assembly  28  for use by an operator, using various different drive mechanisms, to raise the upper portion  15 . The rear upright supports  14 ,  16  provide a connection which passes through the rear cross arm  32  so that activation of the lifting assembly  28  in the driver side rear upright  14  to raise that portion of the roof  18  attached thereto will cause the like portion on the trailer top in the passenger side rear upright  16  to move upward by the same distance, also raising that portion of the roof  18  attached thereto. As a result, it is necessary to only activate the lifting assembly  28 , which may be located in either the driver side or the passenger side upright support  14 ,  16 , to cause the rear portion of the roof  18  to raise in a manner parallel to the trailer bed  20 . In a similar manner, the lifting assembly  28  in the front uprights  14 ,  16  are interconnected through the forward cross arm  34  so that activation of one of the forward lifting assembly  28  will cause the forward edge of the roof  18  to raise uniformly. 
     In order to raise the pair of rear or forward supports  14 ,  16  uniformly, the internal mechanism therein is interconnected by drive means passing through the forward or rear cross arms  34 ,  36 . FIG. 9 shows a cable interconnect while FIG. 11, described below, shows a cross shaft  222  with bevel gears  220  on each end. The cable interconnect uses a cable  60  attached at a first end  62  to the pin  104  through the lower portion  17  and the slot  88  in the upper portion  15  on the passenger&#39;s side and at its second end  64 , to the pin through the lower tube  17  and slot  88  in the upper portion  15  on the driver&#39;s side. The cable  60  on the passenger side then passes around a lower pulley  66  in the lower end of upper portion  15  of the passenger side upright support  14 ,  16  and over two upper pulleys  68  within the space near the juncture of the uprights  14 ,  16  and the cross arm  34 ,  36 . As a result, when the passenger side support upper portion  15  is driven upwards, the drivers side support upper portion  15  is pulled upwards. Of course, the arrangement could be reversed with the lower pulley located in the drivers side upright support  14 ,  16  or two complementary sets of cables  60  (one for a driver side drive mechanism and one for a passenger side drive mechanism) can be used so that a lifting assembly  28  on either upright can be used to lift from either side, or both sides simultaneously. 
     While FIG. 9 shows the lifting assembly  28  as a box mounted on the lower portion  17  of the driver side upright  14 , FIGS. 10 a-e  illustrate several variations of lifting mechanism enclosed within said box. However, these alternative lifting mechanisms are merely representative and are not meant to limit the various different means which may be used to lift the upper portion  15  and hold the raised upper portion at a desired position. Also while various gear combinations are shown, it is contemplated that other means, such as a pneumatic system can be used. FIGS. 10 a-e  show a cutaway view of a portion of a lifting assembly  28  with a rack  52  having a series of parallel notches  50  arranged and equally spaced along a lower end of the additional piece  49  applied to the upper portion  15 . These notches  50  are engaged, as shown in FIGS. 10 a  and  10   b , with teeth  55  on a spline gear  54 . This is commonly referred to as a rack and pinion arrangement. Rotation of the spline gear  54  lifts or lowers the upper portion  15  which in turn raises the roof  18 . FIG. 10 c  shows a worm gear  57 . FIGS. 10 d  and  10   e  show a front and side view respectively of a worm gear, spur gear and rack operating in conjunction. The lifting assembly  28  incorporating the rack, as shown in FIGS. 10 a - 10   e , is driven by a removable and attachable rotary drive, such as an electric drill or a hand crank inserted into the end  58  of the shaft  56  attached to the gear  54 ,  57  portion of the rack and gear arrangement. Alternatively, a female socket can be placed on a matching non-round exposed end  59  of the shaft. Upon activating the drill, the rotating socket or inserted bit causes the gear  54  to rotate driving the lifting assembly  28  upwards. Not shown is a releasable locking mechanism which may be required to hold the upper portion in the extended position until it is released, or a system to prevent rapid lowering of the roof once the locking mechanism is released and the lifting assembly  28  is allowed to lower or causes lowering by driving the gear in the opposite direction. Generally, because of a high mechanical advantage, the worm gear arrangement does not need the lock as it is self breaking. 
     Another lifting mechanism is shown in FIG.  11 . This threaded shaft mechanism  200 , all enclosed with the upright  14 ,  16  comprises a) an outer non-round (i.e., square) tube  202  which can be rotated in bearings  204  but which is fixed from vertical movement, b) a smaller cross section non-round (i.e., square) tube or rod  206  within the outer tube  202 , said small tube or rod  206  being free to rise upward within the outer non-round tube  202 , c) a threaded rod portion  208  affixed to the top of the smaller, inner tube  206  and d) a nut  210  with threads mating with the threaded rod  208 , the nut  210  fixed in location within the upper end of the lower portion  17  of the upright  14 ,  16 . The upper portion of the threaded rod  212 , i.e., the portion above the nut when the lifting mechanism is in its lowest position, is not required to be threaded. The upper end  212  of the threaded rod  208  is rotationally mounted to the upper end of the upper tube  15  through a thrust bearing  214  near the lower end of that upper tube  15 . When the outer non-round tube  202  is rotated, for example by placing a socket wrench into a matching socket  216  in the bottom end of the outer tube  202  and applying a rotational force, the threaded rod  208  rotates in the nut  210  and, depending on the direction of rotation, causes the upper portion  15  supported by the thrust bearing  214  to raise or lower. Mounted on the uppermost end of the threaded rod  212  is a bevel gear  218 . This bevel gear  218  meshes with a second bevel gear  220  on one end of a cross shaft  222  which runs through and across the cross arm  34 . The above described structure is duplicated in the other upright of the paired upright  14 ,  16 . As a result, applying a rotation force to the socket  216  in the bottom of either outer non-round tube  202  not only causes that side of the trailer enclosure to lift but also applies a lifting force to the paired upright connected thereto. 
     FIG. 11 shows a rotating vertical shaft which is driven in a rotational manner at its lower end. This causes the support upper portion  15  to raise and the bevel gear on the top to rotate. As the top half of the shaft rotates and raises, the bevel gear at the top causes a matching bevel gear to rotate, driving a cross shaft and, in turn the paired vertical shaft to also rotate, lifting the other support upper portion. 
     While lifting mechanisms have been described for the rear support assembly  36  the same mechanism can be used in the front support assembly  34 . 
     Another unique feature of the expandable enclosure  10  is that it can be readily removed from the trailer bed  20  by lifting the rear and forward support assembly  36 ,  38  so that the foot  224  on the bottom of the upright supports  14 ,  16  are removed from their locations in the trailer bed  20 . The trailer  12  can then be driven out from under the enclosure  10  to provide an open trailer. Alternatively, if the removal mechanism attached to each upright support  14 ,  16  includes a wheeled base  76 , the enclosure  10  can be wheeled away from the trailer  20 . One means of accomplishing the lifting of the enclosure  10  is to use a bracket  74 , such as shown in FIGS. 12-13 connected to a wheeled base  76 , such as shown in FIGS. 14 and 15, resulting in the wheeled expandable enclosure assembly  78  as shown in FIG.  16 . 
     Referring to FIGS. 12-13, a lifting bracket  74  is shown removably attached to an upright support  14 ,  16  by use of two side extensions  80  placed around the sides of the upright support  14  and a hook  82  placed in the base of the upright  14 ,  16 . Once the bracket  74  is brought against the upright  14 ,  16 , the locking arm  84 , which is held to the bracket  74  by the collars  86 , is rotated in the direction of the arrow in FIG. 13, trapping the upright  14  against the bracket  74  and between the side extensions  80 . If necessary, a pin, not shown, can be placed through the bracket  74  or the extensions  80  in the upright  14 ,  16 . 
     FIGS. 14 and 15 show the wheeled base  76  which includes a vertical lower tube  100  mounted on a base  94  carried by wheels  96  and supported by a diagonal brace  108 . A lifting cylinder  90 , moveably mounted in the lower tube  100 , has a jack hook  182  extending in one direction and lifting plate  184  extending in the opposite direction. Mounted to the outer face of the lower tube  100  is a jack assembly  98  which, in the embodiment shown, has a threaded shaft  92  passing through jack assembly  98  with the top of the threaded shaft  92  resting against the bottom of the lifting plate  184 . 
     In use, the wheeled base  76  is rolled up to the bracket  74  and the lifting cylinder  90  is placed in to the front extensions  186  and locked in place using a pin  104  with the jack hook  182  in the bottom of the bracket  74 . 
     To lift the enclosure, four brackets  74  and four wheeled bases  76  are required. Four braces  26  are mounted at a first end to the roof edge  24  and a second end to a lifting bracket attached to each upright  14 ,  16 . The brackets  74  are attached, one to each upright support  14 ,  16 . Using four wheeled bases  76 , one attached to each upright support  14 ,  16 , through use of the brackets  74  the lifting cylinder  90  in each wheeled base is elevated, thus raising the enclosure  10  and lifting the foot  224  out of the receiving opening in the trailer bed  20 . Once sufficiently elevated the trailer can be moved from under the enclosure or the enclosure can be rolled away from the trailer. The wheeled expandable enclosure assembly  78  after removal from the trailer is shown in FIG.  16 . The triangular brace  26  aids in maintaining the structural shape of the enclosure once removed from the truck bed. Similar triangular supports may also be added to each end of the enclosure. 
     Various different mechanisms may be used to elevate or lower the lifting cylinder  90  in the wheeled base  76 . For example, a lifting mechanism as described above used in the upright supports  14 ,  16  can be used. A preferred mechanism is a worm gear arrangement, such as used in a boat jack, a hydraulic system or a scissor mechanism similar to that used in a typical automotive jack. 
     The above described trailer enclosure is suitable for attachment to a broad range of open bed or open top vehicles. The roof of the enclosure is typically 13′6″ to 14 foot in height. Each of the upper portion  15 , which rests within the lower portion in the telescoping manner, and the lower portion  17 , are about 100-120 inches long. The roof can generally be raised about 18 additional inches, but usually from about 12 to 24 inches. However, the possible elevation of the roof is limited only by the mechanical travel of the upper portion  15  in the upright supports  14 ,  16 . Depending on the nature of the cargo and the method of loading, the roof can be raised temporarily during the loading process to provide more usable area during the loading process. The roof can then be maintained at its elevated position or lowered down to normal height (fourteen feet) during transport of the load. Alternatively, the front or rear of the roof can be independently lowered if such configuration is of benefit. Further, in the case of a compressible load, or a desire to add restraints to movement of the cargo, the cargo can be loaded to a height within the now covered trailer greater than normal and the roof then lowered to contact and, if desired, to compress the load to prevent the load from moving. Because of the materials used to construct the moveable enclosure, the total weight of the enclosure is significantly reduced when compared with non-moveable enclosures which it replaces. For example, a typical moveable enclosure embodying features of the invention weighs about 1500 pounds while a fixed enclosure typically weighs about 3000 pounds. The weight of a fully loaded trailer is generally capped at 80,000 pounds. By using the described moveable trailer enclosure, the cargo weight can be increased by 1500 pounds without exceeding load weight limits. 
     If it is desired to fully enclose the load, curtains or panels can be attached to the roof at the sides and ends of the trailer Adding tarpaulins to cover a load is a common practice on open cargo loads. The presence of a solid roof and sturdy end supports makes this practice easier to accomplish and results in a more secure load. 
     Still further to assure that the legal maximum 14 foot height is not exceeded, fixed length side, front and rear curtains can be provided which cooperate with the moveable roof to provide a high visibility indication if the roof remains elevated above the trailer bed so as to exceed the 14 foot maximum. For example, the end curtains can be attached to the uprights  14 ,  16  so as to leave a visible space between the curtain top and roof edge if the roof is too high. Alternatively, the curtains can be moveably hung from the roof top so that a space remains between the curtain bottom and trailer bed when the 14 foot allowance is exceeded. 
     Another feature of the enclosure is that the roof, while attached to the uprights, is attached on a sliding structure so that movement of the components of the trailer top or elevation of one end of the roof will not cause the uprights on the other end to be placed under stress by a rigid connection. This is best shown in FIG. 17 which shows the floating construction of the connection of one of the uprights to roof. 
     Attached to the upper portion  15  by pin  104  is a mounting bracket  304  having two horizontal rods  300  and a threaded rod  302  which are inserted into matching holes in the end of the roof, side edge  24 ,  42  sized to receive the two rods  300  and the threaded rod  302 . A nut  306  is placed on the end of the threaded rod  302  to keep the roof from disconnecting itself from the attachment to the upper portion  15 . Use of the pin mounting allows the mounting bracket  304  to pivot and the roof to slide along the rods  300 ,  302  as the other end of the roof is raised or lowered. In this manner, one end of the enclosure can be raised, for example, 18 inches. If not for the sliding arrangement described, considerable stress could be placed on the uprights on the other end of the trailer. 
     Although the present invention has been described in considerable detail with reference to certain preferred versions and uses thereof, other versions and uses are possible. 
     Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.