Abstract:
A system for transporting containers includes a trailer frame with independent hoist systems for loading and unloading multiple containers. The trailer frame supports the containers during transport, inclines to load/unload the containers, and supports a tilting sub-frame that loads/unloads a container. Thus, the system is chassis-less.

Description:
This is the U.S. National Stage Under 35 U.S.C. §371 of International Patent Application No. PCT/US2009/062766 filed Oct. 30, 2009, which claims the benefit of U.S. Provisional Application Ser. No. 61/109,831, filed Oct. 30, 2008 and entitled “Dual Container Trailer System.” 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     In the material transport, loading and unloading industry, trailers are used to move containers from place to place. Sometimes multiple types of materials require transport in separate containers, or the load capacity of the trailer must be maximized. A trailer may be outfitted to support two containers. Existing dual container trailers are not always reliable or produce satisfactory results. In particular, the inline positioning of the containers creates logistical problems and speedy loading and unloading is sacrificed. Further, the means for loading and unloading add to the complexity and manufacturing costs of the trailer. 
     The principles of the present disclosure are directed to overcoming one or more of the limitations of existing trailers for loading, unloading and transporting multiple roll-off containers. 
     SUMMARY 
     In an embodiment, a system for transporting containers includes a main trailer frame, a sub-frame coupled to the main frame, a first hoist system to pivot the main frame, and a second hoist system coupled between the main frame and the sub-frame to pivot the sub-frame. The first hoist system may be configured to incline the main frame to load or unload a first container. The second hoist system may be independently operable of the first hoist system to incline the sub-frame to load or unload a second container. A first winch may be coupled to the main frame. A second winch may be coupled to the sub-frame. The main frame may be pivotally coupled to a wheel support assembly, and the sub-frame may be pivotally coupled to the main frame. In some embodiments, the system is chassis-less. 
     In an embodiment, a system for transporting containers includes a first frame defining a top support surface configured to support at least a first container and a second container, a wheel support assembly pivotally coupled to the first frame, and a second frame pivotally coupled to the first frame. The system may further include a first hoist system to pivot the first frame about the wheel support assembly. The system may further include a second hoist system to pivot the second frame relative to the first frame. The first and second hoist systems may operate independently of each other to separately pivot the first and second frames. 
     In an embodiment, a method of transporting containers includes actuating a first hoist system to incline a main frame, providing a sub-frame and a second hoist system coupled to and inclined with the main frame, pulling a first container into a stored position on the main frame, and reclining the main frame using the first hoist system. Actuating the first hoist system to incline the main frame may further comprise pivoting the main frame about a wheel support assembly engaged with the ground. The method may further include actuating the second hoist system, while the main frame is reclined, to pivot the sub-frame relative to the main frame and incline the sub-frame, pulling a second container into a stored position on the sub-frame and the main frame, and reclining the sub-frame using the second hoist system. The method may further include coupling the system to a truck for transport. The method may further include re-inclining the sub-frame to unload the second container with the second hoist system, and separately re-inclining the main frame to unload the first container with the first hoist system. 
     In an embodiment, an apparatus for loading, transporting, and unloading containers including a trailer frame having a front portion and a rear portion, both of which define a top support surface for both transporting the containers and inclining them for loading/unloading. Consequently, in some embodiments, the apparatus is chassis-less. The trailer frame also includes a wheel frame upon which the frame is pivotally mounted. The rear frame portion also includes a sub-frame or tilt frame pivotally mounted thereon for supporting a container. A first pivot operatively connects the rear of the trailer frame and the wheel frame for pivoting the trailer frame and any associated container about a pivot point at the wheel frame. A second pivot operatively connects the rear portion of the trailer frame and the tilt frame for pivoting the tilt frame and a second container about a pivot point located at the rear portion. A first cable drive is located on the front portion of the trailer frame and has an engagement member for engaging a first container and transporting it onto the top support surface of the trailer frame to a transport position. A second cable drive is located on the tilt frame and has an engagement member for engaging the second container and transporting the second container onto the top support surface of the frame to a transport position. A first stop is connected to the trailer frame and a second stop is moveably coupled to the tilt frame such that it can be locked into position above or below the top surface of the tilt frame. 
     In an embodiment of the method of loading a dual container transport trailer with a pair of containers, a first container is moved onto the inclined trailer frame and into the transport position by engaging the container with the engagement member of the first cable drive and actuating the first cable drive until the first container engages a first stop. A second container is moved onto the inclined sub-frame or tilt frame and into the transport position by engaging the container with the engagement member of the second cable drive and actuating the second cable drive until the second container engages a moveable second stop. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more detailed description of preferred embodiments of the present invention, reference will now be made to the accompanying drawings, wherein: 
         FIGS. 1-4  are schematic illustrations of a dual roll-off container trailer in accordance with an embodiment of the invention, with  FIG. 1  depicting a side view of the trailer,  FIG. 2  depicting a top view of the trailer,  FIG. 3  depicting an end view of the trailer, and  FIG. 4  depicting an isometric view of the trailer; 
         FIG. 5  depicts the dual roll-off container trailer with the main trailer frame in the raised position; 
         FIG. 6  depicts the dual roll-off container trailer with the rear tilt frame in the raised position; 
         FIGS. 7   a - 7   i  depict the steps for loading containers using a dual roll-off container trailer, with 
         FIG. 7   a  depicting a first step with the main trailer frame in the lowered position prior to loading the forward container, 
         FIG. 7   b  depicting a second step with the main trailer frame in the raised position prior to loading the forward container, 
         FIG. 7   c  depicting a third step with the main trailer frame in the raised position while the forward container is being retracted and still contacting the ground, 
         FIG. 7   d  depicting a forth step with the main trailer frame in the raised position while the forward container is being retracted to the upper position and fully supported by the trailer, 
         FIG. 7   e  depicting a fifth step with the main trailer frame in the lowered position and the forward container retracted into the transport position, 
         FIG. 7   f  depicting a sixth step with the main trailer frame in the lowered position and the rear tilt frame in the raised position prior to loading the rear container, 
         FIG. 7   g  depicting a seventh step with the main trailer frame in the lowered position and the rear tilt frame in the raised position while the rear container is being retracted and still contacting the ground, 
         FIG. 7   h  depicting an eighth step with the main trailer frame in the lowered position and the rear tilt frame in the raised position while the rear container is being retracted to the rear position and fully supported by the trailer, 
         FIG. 7   i  depicting a ninth step with the main trailer frame in the lowered position and the rear tilt frame in the lowered position and the rear container retracted into the transport position; and 
         FIGS. 7   j - 7   p  depict the steps for unloading containers using a dual roll-off container trailer and are the loading steps  7   a - 7   i  in reverse order. 
     
    
    
     DETAILED DESCRIPTION 
     In the drawings and description that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals. The drawing figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present disclosure is susceptible to embodiments of different forms. Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Unless otherwise specified, any use of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. The various characteristics mentioned above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art upon reading the following detailed description of the embodiments, and by referring to the accompanying drawings. 
     With reference to  FIGS. 1-4 , a moveable container support system designated generally as  10  is shown. The system  10  may also be referred to as a container trailer or a dual roll-off container trailer. The trailer  10  includes a first hoist system  12  and a second hoist system  14 . The first hoist system  12  includes a main trailer frame  13  comprising a forward frame portion  15  and a rear frame portion  17 . A moveable support arm  19  is pivotally mounted to the forward frame portion  15  at a pivot  21 . The moveable support arm  19  includes a support leg  26  resting on ground  5 . A pair of hydraulic cylinders  27  is operably coupled between the forward frame portion  15  and the support arm  19 . In some embodiments, other known extension or actuation means are operably coupled between the forward frame portion  15  and the support arm  19 . A first cable drive mechanism  36  and a first locking member  38  are mounted to the forward frame portion  15 . In some embodiments, the first cable drive mechanism is a winch. In some embodiments, other known drive mechanisms are operably coupled to the forward frame portion  15 . 
     The second hoist system  14  includes a sub-frame or tilt frame  20  pivotally mounted to the rear portion  17  of the main trailer frame  13  at a pivot  22  ( FIG. 4 ). A pair of hydraulic cylinders  37  ( FIG. 2 ) is operably coupled between the tilt frame  20  and the rear frame portion  17 . A second cable drive mechanism  47  is operably coupled to the tilt frame  20  (see  FIG. 6 ). In some embodiments, the second cable drive mechanism is a winch. In some embodiments, other known actuation or drive means are operably coupled to the tilt frame  20 . Supporting the rear frame portion  17  is a wheel support assembly  29  including tandem wheel supporting axles  31 ,  33  and wheels  32 ,  34 . The forward frame portion  15  and the tilt frame  20  generally define a top support surface  25  for supporting roll-off containers as will be further described herein. 
     Referring to  FIG. 1 , the moveable support arm  19  includes a hitch  16  that may be coupled to a truck  7 . The hitch  16  includes a pivot point  18  (shown in  FIG. 5 ). The truck  7  connects to and supports trailer at hitch  16  for moving the trailer  10  between job sites, storage terminals, dumping depots, and the like. 
     Referring now to  FIG. 5 , the trailer  10  is shown in a loading or unloading position using a first hoist system  12 . The frame  13  is rotated about a pivot  30  that couples the rear frame portion  17  and the wheel support assembly  29 . The trailer frame  13  and any container supported thereon may be moved through a range of positions including a horizontal position shown in  FIGS. 1-4  and various degrees of inclination as shown in  FIG. 5  and elsewhere herein.  FIG. 5  also illustrates that the means for rotating the frame  13  about the pivot  30  includes the support arm  19 , the hydraulic cylinders  27  (or, a hydraulic piston/cylinder arrangement) and the hitch  16 . To pivot the frame  13  about the pivot  30 , the movement of both the truck  7  and the axles  31 ,  33  and wheels  32 ,  34  are restricted, either through application of trailer brakes or wheel chalks, or any other means that sufficiently restricts such movement. Alternatively, the truck and axles are left free to move. Then, the hydraulic cylinders  27  are actuated to push the forward frame portion  15  upward at a pivot  35 . As the hydraulic cylinders  27  push up on the forward frame portion  15 , the support arm  19  rotates about the pivots  18 ,  21  and the frame  13  rotates about the pivot  30 . 
     Referring next to  FIG. 6 , the trailer is shown in another loading or unloading position using a second hoist system  14 . The pivot  22  (concealed by structure) connects the tilt frame  21  and the rear frame portion  17  for pivoting the tilt frame  21  and any supported container through a range of positions including a horizontal position show in  FIGS. 1-4  and various degrees of inclination as shown in  FIG. 6  and elsewhere herein.  FIGS. 2 and 6  also illustrate that the means for rotating the tilt frame  21  about the pivot  22  includes two hydraulic cylinders  37  (or, a hydraulic piston/cylinder arrangement) connected to the rear frame portion  17  at pivots  39 . As the cylinders  37  extend, they push on the tilt frame  21  at pivots  40  which causes pivoting of the tilt frame  21  about the pivot  22 . 
     The first hoist system  12  includes the first winch  36  with a first cable or wire  43  coupled to a connector  42  on a first container  23  (shown in  FIG. 7   b ). The winch  36  extends and retracts the cable  43  providing the motive force to the container  23  to travel along the top support surface  25  of the trailer  10 . A first stop member  38  engages the container  23  and locks it in place. 
     The second hoist system  14  includes the second winch  47  with a second cable or wire  49  coupled to a connector  44  on a second container  23 ′ (shown in  FIG. 7   f ). The cable  49  extends from the winch  47 , passes over a roller  53  located at the end of the tilt frame  20 , and extends to the connector  44  on the second container  23 ′. The winch  47  extends and retracts the cable  49  providing the motive force to the container  23 ′ to travel along the top support surface of the tilt frame  20 . A second stop member  48  engages the container  23 ′ and locks it in place. The second stop  48  is moveably coupled (such as hydraulically) to the tilt frame  20  such that it can be positioned for use, projecting above the top surface  25  as shown in  FIGS. 1 and 7   f , or to not interfere with movement of the container  23 , retracted below the surface  25  as shown in  FIG. 7   b . For example, the stop  48  can be rotated about an axis to change its positions. 
       FIGS. 7   a - 7   i  depict the steps in a method for loading containers using a dual roll-off container trailer in accordance with an embodiment of the disclosure. As shown in  FIG. 7   a , the trailer has an initial configuration and is preferably located in proximity with containers that are initially resting at ground level. 
     The containers discussed herein are commercially available from a variety of sources and are used in the refuse and solid waste/sludge handling industries, as well as other industries. The containers can be open topped or closed. For example, the containers could be used as a part of a stationary refuse compaction system. However, the apparatus and method of the present disclosure have application to containers associated with both these and other industries, or to open containers in general which are transported on truck-driven trailers for delivery and drop-off between various locations. 
     Referring now to  FIG. 7   b , the first hoist system  12  is actuated and the main trailer frame  13  is pivoted to the inclined position by the action of the hydraulic cylinders  27  extending between the hitch  16  and the forward frame portion  15 , as previously described. The support arm  19  rotates about the pivots  18 ,  21  and the support leg is lifted off the ground  5 . The frame  13  rotates about the pivot  30  to its inclined and loading position. A first container  23 , positioned on the ground  5 , is coupled to the cable  43  at the connector  42 . 
     Referring now to  FIG. 7   c , the winch  36  retracts the cable  43  and pulls the first container  23  onto the top support surface  25 . Movement of the container  23  is aided by rollers  55 . The stop member  48  is rotated downward so as not to interfere with the container  23 .  FIG. 7   d  shows the container  23  as it is pulled past the stop member  48 . The winch  36  pulls the container  23  until the front frame portion  15  fully supports it and the first stop  38  engages the container, holding it in place. With the first container  23  loaded onto the front frame portion  15 , the hoist system  12  is again actuated and the main trailer frame  13  is rotated about the pivot  30  to bring it to the horizontal or reclined position, as shown in  FIG. 7   e . The container  23  is now in the transport position. To help secure the container  23  to the frame  13 , a first set of locks  64  are actuated to engage the container  23 . Referring to  FIGS. 1 ,  2  and  4 , the locks  64  include an open position, as seen in  FIG. 4 , and rotate upward to secure the container by extending a hydraulic cylinder coupled thereto. The second stop member  48  may now be actuated to its locking position. 
     Referring now to  FIG. 7   f , the second hoist system  14  may now be actuated. The tilt frame  20  is pivoted to the inclined position by extending the hydraulic cylinders  37 . Further, a second container  23 ′ is coupled to the second cable  49  at the connector  44 . 
     Referring next to  FIG. 7   g , the second winch  47  retracts the second cable  49  over the roller  53  and pulls the second container  23 ′ onto the tilt frame  20 . Movement of the container  23 ′ is aided by rollers  57 .  FIG. 7   g  also shows that second stop  48  is rotated and locked into a position above the top of the tilt frame  20 . 
     Referring to  FIG. 7   h , the winch  47  pulls the container  23 ′ until the tilt frame  20  fully supports it and the second stop  51  engages the container, holding it in place. With the second container  23 ′ located on the tilt frame  20 , the second hoist system  14  is again actuated and the tilt frame  20  is rotated about the pivot  22  by the cylinders  37  to bring it to the horizontal position as shown in  FIG. 7   i  by reversing the steps to incline the tilt frame  20  as previously described. This leaves the container  23 ′ in the transport position with both the containers  23 ,  23 ′ resting in a horizontal position upon the support surface of the main trailer frame. As with the container  23 , the container  23 ′ is secured to the frame  13  by actuating a second set of locks  60 . The locks  60  start in an open position, as shown in  FIG. 4 , and a hydraulic cylinder disposed between the non-locking ends of the locking arms is extended to rotate the arms upward and into engagement with the container  23 ′. 
     The containers are unloaded from the trailer  10  by the reverse sequence of steps previously described. The locks  60  are released. In  FIG. 7   j , the second hoist  14  is actuated to raise the tilt frame  20  and the container  23 ′. In  FIG. 7   k , the winch  47  is activated to extend the cable  49  and lower the container  23 ′. In  FIG. 71 , the container  23 ′ is lowered to the ground. The cable  49  may then be disconnected from the connector  44  and the cylinders  37  actuated to lower the tilt frame  20  and return the hoist  14  to its original position. The locks  64  are released. In  FIG. 7   m , the container  23  is now unhindered for unloading. In  FIGS. 7   n  and  7   o , the first hoist system  12  is actuated to raise the frame  13  and the container  23 . The winch  36  is activated to extend the cable  43  and lower the container  23  to the ground. In  FIG. 7   p , the container  23  is unloaded. The cable  43  may be unconnected from the connector  42  and the hoist  12  returned to its original position. 
     In some embodiments, it may be necessary to only transport one container. To desirably locate the container in a middle position, rather than either of the positions of the containers  23 ,  23 ′ as shown in  FIG. 7   i , the first hoist system  12  may be operated as described, with the winch  36  pulling the container to a middle position on the frame  13 . To secure the container in such a middle position, a third set of locks  62  (see  FIGS. 1 ,  2 ,  4  and  7   i ) is provided to engage the container. The middle-positioned container may also be unloaded as described. 
     In exemplary embodiments, the support frames  13 ,  20  operate as both the transport support frames and the moveable hoisting support frames. Thus, a frame or chassis for transport that is separate from inclining support frames is not needed. These embodiments of the system  10  may also be referred to as a “chassis-less” container trailer system. 
     In exemplary embodiments, a trailer system for transporting one or more containers includes a main trailer frame including a front portion and a rear portion defining a top support surface, the main trailer frame including a wheel frame pivotally coupled thereto, the rear portion including a tilt frame pivotally mounted thereto, a first pivot means operatively connected between the rear portion and the wheel frame for pivoting the main frame about a pivot point located on the wheel frame, a second pivot means operatively connected between the rear portion and the tilt frame for pivoting the tilt frame about a pivot point located on the rear portion, a first cable drive means located on the front portion and having an engagement member for engaging a first container and transporting the first container onto the top support surface of the main trailer frame to a transport position, a second cable drive means located on the tilt frame and having an engagement member for engaging the second container and transporting the second container onto the top support surface of the tilt frame to a transport position, a first stop connected to the main frame, and a second stop that is moveably coupled to the tilt frame such that it can be locked into position above or below the top surface of the tilt frame. The first pivot means may comprise a support pivotally connected to the main frame and a hitch, together permitting the main trailer frame and any associated container to pivot about a pivot point located on the wheel frame. The second pivot means may comprise at least one hydraulic cylinder of the type having an associated output shaft, a selected end of the cylinder and shaft being pivotally connected to the main trailer frame, the other end of the cylinder and shaft being pivotally connected to the tilt frame for pivoting the tilt frame and its associated container about the pivot point located on the rear portion. 
     In exemplary embodiments, a method of loading a dual container transport trailer with a pair of containers, the trailer having a main trailer frame including a front portion and a rear portion, both of which define a top support surface, the main trailer frame also including a pivotal wheel frame, the rear portion supporting a tilt frame pivotally mounted thereon for supporting a container, the method comprising providing a first pivot means operatively connected between the rear portion and the wheel frame for pivoting the main frame and any associated container about a pivot point located on the wheel frame, providing a second pivot means operatively connected between the rear portion and the tilt frame for pivoting the tilt frame and a second container about a pivot point located on the rear portion, providing a first cable drive means located on the front portion and having an engagement member for engaging a first container and transporting the first container onto the top support surface of the main trailer frame to a transport position, providing a second cable drive means located on the tilt frame and having an engagement member for engaging the second container and transporting the second container onto the top support surface of the tilt frame to a transport position, moving and locking a second stop into position below the top surface of the tilt frame, moving the main trailer frame from a horizontal transport position to an inclined loading position, moving the first container to the transport position by engaging the container with the engagement member of the first cable drive means and actuating the first cable drive means until the first container engages a first stop, moving the main trailer frame from the inclined loading position to a horizontal transport position, moving and locking the second stop into position above the top surface of the tilt frame, moving the tilt frame from a horizontal transport position to an inclined loading position, moving a second container to the transport position by engaging the container with the engagement member of the second cable drive means and actuating the second cable drive means until the first container engages the second stop, and moving the tilt frame from the inclined loading position to a horizontal transport position. The method may further comprise unloading the double container trailer by moving the tilt frame to the inclined position, moving the second container from the tilt frame to a surrounding support surface using the engagement member of the second cable and actuating the second cable drive means, disengaging the engagement member of the second cable from the second container, moving the tilt frame from the inclined position to a horizontal position, moving and locking the second stop into position below the top surface of the tilt frame, moving the main trailer frame to the inclined position, moving the first container from the main trailer frame to a surrounding support surface using the engagement member of the first cable and actuating the first drive means, disengaging the engagement member of the first cable from the first container, and moving the main trailer frame from the inclined position to a horizontal position. 
     While embodiments of the disclosure have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the disclosure disclosed herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.