Abstract:
The invention relates to a side lifting/closing tarpaulin system for a flatbed trailer, the trailer having an elongated platform having front and rear ends, sides, a pair of bulkheads of similar construction extending upwardly from the platform at its front and rear ends, and a plurality of tarpaulin supporting beams extending laterally across the platform, and longitudinally along the platform. The system comprises a pair of pivoting arms, each arm supported by a corresponding bulkhead. The arms are pivotable, in corresponding fashion, with respect to a side of the platform, between an upper, open orientation and a lower, closed orientation. Each arm is provided with an elongated slot along a longitudinal axis of the arm. Each arm is mounted relative to the bulkhead such that the pivot sits within the slot in a manner that permits longitudinal movement of the arm relative to the pivot. There is further provided mechanical drive means to rotate the roller to roll or unroll the tarpaulin thus causing movement of the arms between the open and closed positions.

Description:
RELATED APPLICATION 
   This application claims the benefit under Title 35, U.S.C., S.119(e) of Canadian application No. 2,582,619 filed on Mar. 22, 2007. 
   FIELD OF THE INVENTION 
   The present invention relates to a side roll up tarpaulin system for use with semi-flatbed trailers, truck bodies or utility tag along trailers. As well the system can be adapted to open top trailers or truck bodies for the purpose of covering or uncovering loads. 
   BACKGROUND OF THE INVENTION 
   The transportation of heavy cargo is often done by truck and transport trailers. In some cases, it is feasible to transport the goods within a conventional closed trailer, accessible from the rear doors. However, for some cargo it is required to have the trailer accessible from the sides. For example, in the transport of sod, the cargo cannot be efficiently loaded from the rear. Thus, flatbed trucks wherein the cargo can be loaded and unloaded from the sides are often used in the transport of such types of cargo. 
   For the transport of sod, in particular, it is mandated that the cargo loaded flatbed be enclosed so as to prevent spillage of the sod. In many cases this is done with a tarpaulin system that spans the length of the flatbed trailer, from front to rear between bulkheads at either end and that is retractable to allow for the sides to be open for loading and unloading and closed for transport. Thus there is a need for a system to move the tarpaulin system effectively and efficiently between the open and closed positions. 
   Many manual systems have been devised and implemented, there are known deficiencies. For example, some systems require the operator or driver to climb up on top of the load to release and/or secure the tarpaulin at the top and then climb down to secure and/or release the tarpaulin at the bottom. This results in increased risk of injury as well as inefficiencies in the movement of the tarp. 
   Other systems attempt to employ a remotely activated means of moving the tarpaulin between the open and closed positions. However, many of those incorporate expensive of bulky constructions or do not allow for the tarp to be held in an intermediate position between the fully open and fully closed positions. In one such construction, of Poyntz (U.S. Pat. No. 6,779,828) the control arm located at the front and rear bulkheads to open and close the tarpaulin is a telescoping arrangement. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide an improved side roll up tarpaulin system for use with a flatbed truck, trailer or open top trailer 
   According to one aspect of the invention, there is provided a side lifting/closing tarpaulin system for a flatbed trailer, the trailer having an elongated platform having front and rear ends, sides, a pair of bulkheads of similar construction extending upwardly from the platform at its front and rear ends, and a plurality of tarpaulin supporting beams extending laterally across the platform, and longitudinally along the platform. The system comprises a pair of pivoting arms, each arm supported by a corresponding bulkhead. The arms are pivotable, in corresponding fashion, with respect to a side of the platform, between an upper, open orientation and a lower, closed orientation. Each arm is pivotable in a plane parallel to that of the corresponding bulkhead about a pivot mounted to the bulkhead. There is further provided a roller bar extending between and supported by an outer end of each of the arms. The tarpaulin is supported in rolled fashion on the roller bar when the arms are in upper, open orientation, opening the corresponding side of a trailer and being supported by the support beams. The tarpaulin is rolled off the bar to enclose the corresponding side when the arms are in lower, closed position. Each arm is provided with an elongated slot along a longitudinal axis of the arm. Each arm is mounted relative to the bulkhead such that the pivot sits within the slot in a manner that permits longitudinal movement of the arm relative to the pivot. There is further provided mechanical drive means to rotate the roller to roll or unroll the tarpaulin thus causing movement of the arms between the open and closed positions. 
   While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the present patent specification as a whole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which: 
       FIG. 1  is perspective view of the system of the invention mounted on a trailer; 
       FIG. 2  is an elevation view of the front bulkhead with the arm of the invention mounted thereto; 
       FIG. 3  is an elevation view of the rear bulkhead with the arm of the invention mounted thereto; 
       FIGS. 4   a  and  4   b  are plan views, partially cut away, of the arms of the present invention; 
       FIG. 5  is a partially exploded view of the top rail of the present invention; 
       FIGS. 6   a  and  6   b  show plan views of the system in place in alternate tarping arrangements. 
   

   The present invention will now be described by way of a non-limiting description of certain detailed embodiments. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description, similar features in the drawings have been given identical reference numerals where appropriate. All dimensions described or suggested herein are intended solely to illustrate an embodiment. These dimensions are not intended to limit the scope of the invention that may depart from these dimensions. 
     FIG. 1  illustrates a system  10  for raising and lowering a tarpaulin  12  between an open and closed position mounted on a flatbed trailer  14  of a type suitable for carrying cargo, such as sod  16  or other cargo like wood, building supplies or the like that is required to be enclosed while being transported by flatbed trailer. The trailer  14  is of conventional design with an elongated platform  18  lying horizontally between a front end  20  and a rear end  22 . The trailer  14  is further defined by sides  24 ,  26  and front bulkhead  28  and rear bulkhead  30 . There is provided a plurality of support beams  32  extending laterally across the platform  18  and evenly spaced longitudinally along the length of the platform  18 . The bulkheads  28 ,  30  include support or brace beams  34 . There is further provided a mounting plate  36  mounted to the beams  34  of the front bulkhead  28  to accommodate the system  10 . On the bottom of the platform  18  is a longitudinally extending downwardly facing flange  19  which creates a lip on the bottom edge of the platform  18  along its length. 
   The system comprises a first arm  40  located at the front end  20  of the platform  18 , and is preferably mounted to the front bulkhead  28 . The first arm  40  comprises a tarp end  42  and a pivot end  44 . As shown in  FIG. 3 , a second arm  46  is located at the rear end  22  of the platform  18  and is preferably mounted to the rear bulkhead  30 . The second arm  46  also comprises a tarp end  48  and a pivot end  50 . As illustrated in the drawings, the second arm  46  located at the rear end  22  comprises a straight arm design or off-set or jog  51  along its length. This is to accommodate the optional design of the rear bulkhead  30  set ahead or shaped and sized to accommodate a forklift or the like often mounted to the trailer  14 . Both the first and second arms  40 ,  46  are rigid and of a fixed length. 
   The trailer  14  is further fitted with a tarp roller  52  that carries the tarpaulin  12  on a spindle  54 . The tarpaulin  12  on the roller  52  is supported in the open position, in which the tarpaulin  12  is rolled on the roller  52 , by a top rail  56 . The top rail  56  can be any fixed length to match the length of the platform  18  or can be adjustable in length by being of a telescoping arrangement. As shown in  FIG. 5 , the rail  56  may be comprised of an inner tube  58 , a middle tube  60  and a four sided outer tube  62  whereby the top &amp; side outer edges are cut back to allow the tarpaulin to lay flush and to reduce the wear on the tarpaulin as it passes over the edges of the rail  56  The tubes can be made of steel, aluminum or other suitable material for the load. In one embodiment of the invention, the rail  56  has a square cross-section and the inner  58 , middle  60  and outer  62  tubes are 1.5″×1.5″, 2.0″×2.0″ and 2.5″×2.5″ respectively. Those skilled in the art will appreciate that other dimensions may be used but it is preferred that the relative dimensions remain essentially the same. In this way, the inner  58 , middle  60  and outer  62  tubes can be moved relative to one another in conventional fashion in order to adjust the length of the top rail to match different lengths of platform  18  and accommodate different lengths of spindle  54  and roller  52 . 
   With reference to  FIGS. 4   a  and  4   b , the assembly of arms  40  and  46  will be discussed in greater detail. The arms  40 ,  46  each comprise a beam  70  and end caps  74  at the tarp end  42 ,  48  and pivot end  44 ,  50 . The caps can be bolted on or affixed in any similar means but are preferably not permanently attached. At the tarp ends  42 ,  48  the arms  40 ,  46  each comprise a keyway  80  flanked by flanges  82   a  and  82   b  to accommodate shaft  84  and bearing. There is also a collar  88  to ensure a proper fit. On the first arm  40 , the shaft  84  rotationally carries chain wheel  90 . On both the first  40  and second  46  arms, the shaft  84  rotationally mates with spindle  54  at front and rear ends of the roller  52  in order to rotate the roller  52  to roll and unroll the tarpaulin  12 . This will be described in greater detail in the operation of the system. 
   At the pivot ends  44 ,  50 , the arms  40 ,  46  have an elongated slot  94  along the longitudinal axis of the arm. The slot  94  is of sufficient width to accommodate a shaft  96  that is mounted on the mounting plate  36  and extends laterally outward from the front bulkhead  28 . At the rear bulkhead  30 , the shaft  96  may be mounted to mounting plate (not shown) or directly to the bulkhead  30  or brace  34 . In this way, the arms  40 ,  46  are free to cam or float along the length of the slot  94  by rotating over the shaft  96  as the arms  40 ,  46  move through an arc of rotation in a plane parallel to the bulkheads. 
   There is further provided housed within the slot  94  a biasing means such as a spring  98  as shown. Other suitable biasing means such as a spring plate, coil or helix may be used. The spring  98  is preferably a compression spring and is mounted between a plate and the end cap  74 . The spring  98  is placed on a rod that has been welded to plate  99  and the plate and spring are then placed within the arm  40  resting on a mounting bolt of the arm assembly. In one embodiment, the end cap  74 , having an aperture in its center, is placed over the rod and held in place, for example with a washer and retainer ring. The compression force of the spring  98  acts upon the end cap  74 , and consequently the arm, in such a way as to pull the arm upward and inward relative to the side  24  when the arm  40  is in the lower position ensuring that the unrolled tarpaulin locks under the flange  19 . When the arms are being raised, the spring provides a tension on the roller to ensure a smoother transition to the upper position. 
   Looking specifically at the first arm  40 , the pivot end  44  will be discussed in greater detail. The pivot end  44  comprises the elongated slot  94  which accommodates the shaft  96  and further houses the spring  98 . There is also a control means  100  for rolling and unrolling the tarpaulin  12 . As illustrated in, the control means  100  may be a crank shaft  102  that can be turned manually by a handle  104  by an operator (not shown). The shaft  102  further holds a chain drive wheel  106  which, with the chain wheel  90 , carries a chain  108 . As seen in the figures, the chain  108  is protected by a chain guard  109 . The handle  104  is used to rotate the chain drive wheel  106  thus rotating the chain  108  causing rotation of the chain wheel  90 . The rotation is then transferred to tarp roller  52  causing the tarp  12  to be rolled or unrolled depending on the direction of the rotation. The shaft  102  is mounted to the beam  34  of the front bulkhead  28  and passes through a bearing keyway  109  in the arm  40 . 
   Alternatively, the rotation of the shaft  102  may be caused by motorized means such as a electric, pneumatic or hydraulic drive controlled by a user interface  110 . The motorized control can be selectively disconnected or bypassed to allow the operator to use the manual control in the event that the motorized control is either not available or not desirable. 
   Further housed within the first arm  40  is the locking mechanism  120 . The locking mechanism  120  comprises a ratchet  122  with a double lever pawl  124  that is designed to automatically engage the ratchet teeth  126  and stop rotation in one direction upon cessation of rotational force but allow free movement in the opposite direction. The lever  124  can be manually reversed however in order to selectively stop rotation in the other direction. In this way, the movement of the arms  40 ,  46  can be automatically locked as the arms are being raised and rotation is ceased. As the arms are being lowered the rotation can be selectively stopped by manually engaging the lever  124  into its locked position. 
   The operation of the system  10  will now be described with reference to the unrolling and lowering of the tarpaulin  12  from the open position to the closed position in which the side  24  of the trailer  14  is enclosed, thus securing the cargo  16 . It will be understood that the raising and rolling of the tarpaulin  12  is essentially the reverse operation, although the differences, such as the operation of the locking ratchet  122  during the raising will be explained. 
   In the rolled position, the tarpaulin  12  is supported on the top rail  56  and the first arm  40  and second arm  46  are both in the upper position. The control means  100  at the pivot end  44  of the first arm  40  is engaged by the operator. If the manual mode is being used, the crank shaft  102  is released by unlocking the locking mechanism  120  and the handle  104  is rotated in order to impart rotation to the chain drive wheel  106  thus rotating the chain  108 . This imparts rotation to the roller  52  by means of the spindle  54  and the chain wheel  90  at the tarp end of the first arm  40 . This rotation causes rotation of the spindle  54  at the tarp end  48  of the second arm  46 , such that the rotation of the handle  104  causes the roller to begin unrolling the tarpaulin  12 . 
   As seen, partially in phantom in  FIGS. 2 and 3 , as the tarpaulin  12  is unrolled it begins to lower to cover the side  24  of the trailer  14 . As the tarpaulin  12  is lowered the arms  40 ,  46  begin to move in a plane parallel to the plane of the bulkheads  28 ,  30  through a range from the upper to the lower positions. Since the arms  40 ,  46  are rigid and of fixed length, the rotation of the arms is translated to a longitudinal movement of the arm lateral to the plane of the bulkheads  28 ,  30  characterized by the movement of the slot longitudinally relative to the pivot shaft  96 , in a cam like fashion. The first arm  40  is moved from its upper to lower position. In a slave arrangement, the second arm  46  follows the same movement. 
   At any point during the movement, the lowering of the tarpaulin  12  can be arrested by engaging the locking mechanism  120 . During downward movement, the pawl  124  will not engage the teeth  126  unless the direction of the paw  124  is manually switched to a locking position in which position the pawl  124  is oppositely facing so as to abut one of the teeth  126  to prevent further rotation. This is to be distinguished from the raising movement in which the pawl  124  travels over the teeth  126  in such a way as to automatically engage the teeth  126  to prevent rotation in the opposite (namely downward) direction should rotation of the wheel stop. 
   Once the tarpaulin  12  has been fully rolled out and the side  24  has been covered, the spring  98  urges the arms  40 ,  46  to slide upward thus forcing the bottom of the tarpaulin  12  up under the flange  19  into a locked position for transport. Further securing means such as tie downs and clamps that are common in the industry can be used. 
   To begin to roll the tarpaulin  12  to raise it, the biasing of the spring  98  is overcome to allow the end of the tarpaulin  12  to clear the flange  19  and then the rotation of the roller  52  is effected in much the same way as when the tarpaulin  12  was lowered. 
   Although the system  10  has been illustrated with a tarpaulin  12  extending over the side  24  of the trailer  14 , it will be understood that the system could comprise tarpaulins that when rolled are located at the centre of the top of the trailer in such a way that when unrolled in opposite directions, the tarpaulins not only cover the sides  24 ,  26  of the trailer  14  but also define the roof covering  140 . In such a system, the tarpaulins would each have a pair of arms and drive system in a manner as described but the arms may be manufactured longer to accommodate the increased range of movement as the tarpaulin is rolled and unrolled. Similarly, it is contemplated to have a configuration in which one side  24  is covered and uncovered by a tarpaulin in the manner described herein and a second tarpaulin the is sized to cover and uncover the other side  26  and define the roof covering  140 . 
   Although the present invention has been described by way of a detailed description in which various embodiments and aspects of the invention have been described, it will be seen by one skilled in the art that the full scope of this invention is not limited to the examples presented herein. The invention has a scope which is commensurate with the claims of this patent specification including any elements or aspects which would be seen to be equivalent to those set out in the accompanying claims.