Abstract:
An extendable multi-stage trailer loader or unloader apparatus includes a frame assembly having first and second frame members that are interconnected. The second frame member is selectively extendable from the first frame member. A first conveying surface is supported by the first frame member and defines a first conveyor. The first conveying surface is operable to convey articles between an upstream end of the first conveyor and a downstream end of the first conveyor. A second conveying surface is supported by the second conveying member. The second conveying surface is defined by a second conveyor. The second conveying surface is operable for conveying articles between the downstream end of the first conveyor and a downstream end of the second conveyor. The second conveyor includes a flexible support supporting the second conveying surface.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from U.S. provisional patent application Ser. No. 60/682,887, filed on May 20, 2005, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to conveyors and in particular to a multiple stage arrangement for loading and/or unloading trailers, and the like, from a dock area.  
         [0003]     Large trailers and other similar cargo carrying vehicles are typically loaded and unloaded from an elevated dock area of a warehouse or factory where space is often limited. The bays in loading docks are rather narrow and spaced closely together in a side-by-side fashion. Conventional telescoping or extending conveyors may be used to transport packages from a loading dock into a trailer or truck bed. Such a trailer loader is disclosed in the commonly assigned U.S. Pat. No. 4,425,069 filed Jun. 12, 1981, by Saur et al., and entitled TRANSPORT FOR LOADING SEMITRAILERS AND THE LIKE, the disclosure of which is hereby incorporated herein by reference. Such conveyors are at a grade to transport packages by the force of gravity. It is known to provide such conveyors having two-part conveyor arrangements with angled transition sections in between each part of the conveyor. In certain situations, the grade of the conveyor causes packages to accelerate at high and uncontrollable speeds, which may result in jams. Additionally, the angled transition section may cause packages to gain speed and/or jump, loss of control of packages, resulting in potential jams on the conveyor, and packages toppling over or off the conveyor causing damage.  
         [0004]     Thus, there is a need and desire for a conveyor system for loading trailers, and the like, which moderates the flow, speed and orientation of packages conveyed on such telescoping conveyors to prevent jams and damage to packages.  
       SUMMARY OF THE INVENTION  
       [0005]     Accordingly, the present invention provides an expandable multiple-stage trailer loader which overcomes a number of the above-discussed difficulties.  
         [0006]     An extendable multi-stage trailer loader or unloader apparatus according to an aspect of the invention includes a frame assembly having first and second frame members that are interconnected. The second frame member is selectively extendable from the first frame member. A first conveying surface is supported by the first frame member and defines a first conveyor. The first conveying surface is operable to convey articles between an upstream end of the first conveyor and a downstream end of the first conveyor. A second conveying surface is supported by the second conveying member. The second conveying surface is defined by a second conveyor. The second conveying surface is operable for conveying articles between the downstream end of the first conveyor and a downstream end of the second conveyor. The second conveyor includes a flexible support supporting the second conveying surface.  
         [0007]     An extendable multi-stage trailer loader or unloader apparatus according to another aspect of the invention includes a frame assembly made up of first and second frame members that are interconnected. The second frame member is selectively extendable from the first frame member. A first conveyor is supported by the first frame member. The first conveyor is made up of a conveyor belt and a drive motor for driving the conveyor belt. The conveyor belt defines a first conveying surface operable for conveying articles from an upstream end to a downstream end of the first conveyor. A second conveyor is supported by the second frame member. The second conveyor is made up of a second conveying surface extending from the first frame member. The second conveying surface is operable for conveying articles from the downstream end of the first conveying surface to a downstream end of a second conveying surface. The second conveying surface is made up of a plurality of freely rotating conveying members and a flexible support. The flexible support supports the freely rotating conveying members from a portion of an upward facing surface of the second frame member that is extending beyond the first frame member.  
         [0008]     An extendable multi-stage trailer loader or unloader apparatus according to yet another aspect of the invention includes a frame assembly made up of first and second frame members that are interconnected. The second frame member is selectively extendable from the first frame member. The first conveying surface is supported by the first frame member. The first conveying surface is defined by a first conveyor. The first conveying surface is operable to convey articles between an upstream end of the first conveyor and a downstream end of the first conveyor. A flexible second conveyor is supported by the second frame member. The flexible second conveyor defines a second conveying surface. The second conveying surface is operable for conveying articles between the downstream end of the first conveyor and a downstream end of the second conveyor. The flexible second conveyor is attached at opposite ends to the first frame member and extends around the second frame member. The flexible second conveyor has a first portion supported at an upper portion of said second frame member and a second portion supported at a lower portion of said second frame member. Relative lengths of the first and second portions are different for different relative positions of the first and second frame members.  
         [0009]     These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a side elevation of an extendable multiple-stage transportable trailer loader or unloader apparatus according to the present invention in a partially extended position;  
         [0011]      FIG. 2  is the same view as  FIG. 1  in a retracted position;  
         [0012]      FIG. 3  is a front elevation taken in the direction III-III in  FIG. 2 ;  
         [0013]      FIG. 4  is an enlarged view of the area IV in  FIG. 1 ;  
         [0014]      FIG. 5  is a top plan view taken in the direction V-V in  FIG. 4 ;  
         [0015]      FIG. 6  is the same view as  FIG. 4  of an alternative embodiment of the present invention;  
         [0016]      FIG. 7  is the same view as  FIG. 5  of the embodiment illustrated in  FIG. 6 ; and  
         [0017]      FIG. 8  is the same view as  FIG. 4  of another alternative embodiment of the present invention;  
         [0018]      FIG. 9  is the same view as  FIG. 5  of the embodiment illustrated in  FIG. 8 ;  
         [0019]      FIGS. 10   a  and  10   b  are side elevational views of yet another alternative embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Referring now to the drawings and the illustrative embodiments depicted therein, an extendable multiple-stage trailer loader apparatus  10  includes a first section  11  having a first frame member  12  and a first conveyor  15  having a first conveying surface  16 . Apparatus  10  further includes a second section  13  having a second frame member  14  and a second conveyor  17  having a second conveying surface  18 . Conveying surfaces  16 ,  18  define a main conveying surface  20  ( FIG. 1 ). Second frame member  14  retracts to and extends from first frame member  12  to adjust the overall length of main conveying surface  20  of trailer loader  10 .  
         [0021]     As best illustrated in  FIG. 3 , downward facing surfaces  45  of second frame member  14  engages a series of guide wheels  46  mounted on first frame member  12  at the bottom of the side members  48  of the first frame member. Guide wheels  46  allow second frame member  14  to retract to and extend from first frame member  12 . Alternatively, in keeping within the spirit of the invention, guide wheels  46  may be attached to second frame member  14  and roll along the side channel of first frame member  12 . Moreover, other sliding or rolling mechanisms are contemplated by the present invention, such as roller balls, sliding roller cantilevers, and the like. Side plates  50  may be provided that extend outwardly of the side members to provide additional stiffness to first frame member  12  as well as to generally cover second frame member  14 .  
         [0022]     Apparatus  10  further provides a substantially planar main conveying surface  20  formed by first conveying surface  16  generally supported by first frame member  12  and second conveying surface  18  generally supported by second frame member  14 . The overall length of main conveying surface  20  is adjustable. The length of first conveying surface  16  is fixed. The length of second conveying surface  18  is determined by the position of second frame member  14  with respect to first frame member  12  providing a plurality of different lengths for the second conveying surface. Regardless of the relative retraction or extension of frame members  14 ,  16 , the tension on second conveying surface  18  remains generally constant to maintain a planar main conveying surface  20  as the second conveying surface wraps underneath the second frame member, which is discussed in greater detail below.  
         [0023]     In the illustrated embodiments, first conveying surface  16  is a belt conveyor reaved about a motor driven pulley  22  and idler pulley  23 . First conveying surface  16  transports articles or packages toward second conveying surface  18 . The motor for driven pulley  22  can be mounted under first conveying surface  16  and up between side members  48  of first frame member  12 . Alternatively, first conveying surface  16  may be a gravity roller conveyor, a powered roller conveyor, a gravity wheel conveyor, or any like gravity conveyor. In yet another embodiment, first conveying surface  16  may be divided into a plurality of zones or beds with a plurality of motorized rollers  22  and article sensors (not shown), with one motorized roller and article sensor per zone, to accommodate greater conveyor lengths and provide greater control of packages conveyed such as by facilitating accumulation of articles in the zones, as is known in the art. First conveying surface  16  may be driven at a constant or an adjustable speed by motor  22  to feed packages onto second conveying surface  18 .  
         [0024]     Second frame member  14  supports second conveyor  17  which is illustrated as a flexible web and may include a pair of flexible supports  52 , such as laterally spaced apart chains. Each flexible support  52  is received and supported by an upper upward facing surface  45  and a lower upward facing surface  47  of second frame member  14 . Each flexible support  52  in the illustrated embodiments is a chain made up of a series of links  53 , each interconnecting adjacent axles  58  of rollers  55 . Each flexible support  52  is generally restrained in its axes of elongation, meaning that it will not significantly elongate when pulled from opposite ends. However, each flexible support  52  is flexible perpendicular to its axis of elongation, thus allowing the flexible support  52  to wrap to, for example, 180 degrees as seen in  FIG. 4 . Flexible support  52  may be other flexible elongated members including, but not limited to, cables, articulated plates, plastic mesh, and the like. Second conveyor  17  further includes a second conveying surface  18  received between and laterally supported by flexible supports  52 . Conveying surface  18  may be defined by a plurality of evenly spaced elongated members  55 , such as gravity rollers supported by flexible supports  52 . Rollers  55  are rotatably mounted by axles  58  which are supported at opposite ends by respective flexible support  52 . In this manner, rollers  55  form a gravity roller conveying surface  18  that transports packages under the force of gravity, so long as second conveying surface  18  is pitched. Alternatively, conveying surface  54  may accommodate a plurality of free-rotating conveying members, such as roller wheels, roller balls, or the like. If it is desired to provide a trailer unloader, rollers  55  may be powered rollers, or may be rotated by a powered belt, both of which are known in the art, or the like.  
         [0025]     In another embodiment of the invention, second conveying surface  18  may be defined by a flexible web (not shown) between a pair of laterally spaced flexible supports  52  with a plurality of freely rotating conveying members joined to the flexible web. The flexible web may be in the form of a flexible weave or cross pattern, while keeping within the spirit of the invention, so long as the material provides a planar conveying surface which is capable of providing a surface to transport packages with either gravity or by rollers. Alternatively, flexible conveying surface  18  may be made of a material with a low coefficient of function which allows packages to slide down at a slower rate of speed under the pace of gravity.  
         [0026]     In yet another embodiment, flexible conveying surface  18  may provide a series of evenly spaced rotating members, such as wheels, mounted to axles that are supported at opposite ends by respective flexible support  52 . Other members, which may be rods, tubes, slates, or the like, may be provided to receive and accommodate freely rotatable conveying members to form conveying surface  54 .  
         [0027]     In the illustrated embodiment, flexible supports  52  of second conveyor  17  connect to first frame member  12  and are horizontally supported by upward facing surfaces  45 ,  47  of second frame member  14 . Second conveyor  17  extends around the distal end of second frame member  14  over a toothed sheave  76  and wraps underneath or below the second frame member where it is supported by lower upward facing surfaces  47 . The other end of flexible supports  52  attaches to a pair of cables  24 . Cables  24  wrap around the upstream end of second frame member  14 , such as by a sheave  78 . Cables  24  terminate to the downstream end of first frame member  12  by way of a tensioning member, such as a spring  80 , which assists in maintaining a constant tension on second conveyor  17 .  
         [0028]     In the illustrative embodiments, the sum length of flexible supports  52  and cable  24  of second conveyor  17  are fixed. As second frame member  14  moves relative to first frame member  12 , second conveyor  17  is exchanged between upper and lower support surfaces  45 ,  47 , while cable  24  maintains the tension as the second conveyor moves about toothed sheave  76 . For example, as second frame member  14  extends from first frame member  12 , a greater portion of second conveying conveyor  17  moves to the top of the second frame member and less on the bottom as seen in  FIG. 1 . As second frame member  14  retracts with respect to first frame member  12 , a greater portion of second conveyor  17  is displaced and moved to the bottom of the second frame member and less on top as seen in  FIG. 2 . Flexible members  52  do not move relative to first frame member  12  as the second frame member slides along flexible members  52  during the retraction and extension of second conveying surface  18 .  
         [0029]     In another embodiment of the present invention, flexible support  152  may be a conventional chain having two or more links between each roller  55  ( FIGS. 6 and 7 ). In yet another embodiment, flexible support  252  may include an end plate  62  to support and receive a chain wheel  64  and elements of flexible conveying surface  54  ( FIGS. 8 and 9 ). End plate  62  may be received and mounted to the side of chain  252 , and received by at least two links of the chain. In this illustrated embodiment, end plate  62  is received on chain  252  on the side away from flexible conveying surface  54 . End plate  62  includes flexible conveyor surface member holes  66  and chain wheel holes  68 . Chain wheels  64  are supported by surfaces  45 ,  47  of second frame member  14 . Flexible conveying surface member holes  66  receive an extended axle of gravity rollers  58 , which are then bolted or attached in some other manner, such as by a cotter pin, or the like.  
         [0030]     Trailer loader/unloader apparatus  10  may include a rear set of wheels  26  attached to first frame member  12 . Trailer loader  10  further includes a middle set of wheels  28  and a front set of wheels  30  attached to second frame member  14 . Wheel sets  26 ,  28 , and  30  are preferably in pairs. Wheel sets  26 ,  28 ,  30  support, maneuver and position trailer loader/unloader apparatus  10  into a trailer to load or unload packages. One or more of wheel sets  28  and  30  may be motorized and also may have the capability to steer for controlling the position of trailer loader  10 . When second section  13  reaches full extension, the driven wheels then pull first section  11  forward in unison with the second section, as illustrated in U.S. Pat. No. 7,004,308 B2, the disclosure of which is hereby incorporated herein by reference.  
         [0031]     Alternatively, as second frame member  14  retracts into first frame member  12 , when second frame member  14  reaches full retraction, it drives first section  11  backwards or to the right as viewed in  FIGS. 1 and 2 . Therefore, second frame member  14  must either be fully extended or fully retracted with respect to first frame member  12  before it moves first section  11  forward or backward.  
         [0032]     Movement and maneuvering of trailer loader  10  can be controlled through a control panel (not shown), which may be located on the forward end of trailer loader/unloader apparatus  10  or remotely with a wireless communication means, such as radio frequency, or the like.  
         [0033]     Alternatively, a trailer loader  110  may be provided that includes cantilever supported members. For example, second frame member  114  may be cantilevered to and supported by first frame member  112 , as best illustrated in  FIG. 10   a . Cantilevered trailer loaders and unloaders are known in the art and are disclosed by way of example in U.S. Pat. No. 6,006,893, filed Feb. 13, 1997, by Gilmore et al., and entitled EXTENDABLE TRAILER LOADER/UNLOADER WITH USER INTERFACE SECTION; U.S. Pat. No. 6,481,563 filed Dec. 29, 1999, by Gilmore, and entitled EXTENDABLE CONVEYOR WITH ADDITIONAL BOOM SECTION; and U.S. Pat. No. 6,571,938 filed Oct. 10, 2002, by Gilmore, and entitled EXTENDABLE CONVEYOR WITH ADDITIONAL BOOM SECTION, the disclosures of which are incorporated herein by reference. The plurality of cantilevered sections  114  of trailer loader  110  are illustrated in  FIG. 10   b  in an extended position, extending from first frame member  112 .  
         [0034]     Having described the invention in connection with certain specific embodiments thereof, it is to be understood that the description is meant to be interpreted as illustrative only, and that various modifications may also be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the accompanying claims.