Abstract:
A fold linkage is provided that is usable in combination with a conveyor assembly having a foldable conveyor section and a main conveyor section. The fold linkage includes linkage members and hinge sections that are rotatably attached to each other and that are connectable to the conveyor sections without interference with the conveyor assembly truss members. The fold linkage further includes a pressure operated cylinder that is extendable and retractable so as to fold and unfold the conveyor assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a fold linkage for a conveyor that permits the conveyor to be folded for transport, and more particularly, relates to a fold linkage that may be preassembled and mounted onto the conveyor while avoiding modification of the conveyor frame. 
     2. Discussion of the Related Art 
     Methods for folding a conveyor to facilitate transport are well known. Prior assemblies typically include a foldable conveyor section that is hingedly attached to a main conveyor section via a fold linkage, which includes a plurality of linkage members that are attached to the conveyor frame. Typically, the fold linkage includes a fluid operated cylinder having an extendible piston that is attached to one of a plurality of the linkage members, which are rotatably attached to each other via a corresponding plurality of joints. More specifically, the joints may rotatably connect the linkage members to the rod, the main conveyor section, and/or the folding conveyor section. As a result, actuation of the hydraulic cylinder correspondingly folds or unfolds the foldable conveyor section about the main section via the fold linkage until the conveyor is configured for transport or operation, respectively. 
     Conventional fold linkages suffer from several drawbacks. Specifically, because a plurality of the joints attaches the linkage members directly to the truss frame members, manufacture of prior told linkages is expensive and inefficient. The truss frame is therefore modified within tight tolerances in order to accommodate the joints of the fold linkage. This requires significant time and expense. 
     Additionally, in some prior fold linkage assemblies, the first and second linkages are joined by links that extend through the conveyor, resulting in further necessary modifications to the truss members. The interaction between prior fold linkages and truss members prohibits manufacture of a modular fold linkage prior to attaching the linkage onto the conveyor. Instead, the fold linkage needs to be assembled while, at the same time, integrated with the truss members and frame. 
     What is therefore needed is a fold linkage for a conveyor that is modular so as to allow the fold linkage to be preassembled before being mounted onto the conveyor, and that includes joints that are free from contact and interference with the truss members. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a fold linkage that is usable in combination with a conveyor to fold and unfold the conveyor. 
     It is a further object of the invention to provide a fold linkage that is modular and that is configured so as to be pre-assembled into a fixture prior to being mounted onto the conveyor. 
     It is a further object of the invention to provide a fold linkage that does not require modification of the truss members of the conveyor when the fold linkage is mounted onto the conveyor. 
     It is a further object of the invention to provide a fold linkage having a relief valve to accommodate a hopper that is disposed on the conveyor. 
     It is a further object of the invention to provide a method of producing a fold linkage that incorporates at least some of the above-mentioned objects. 
     It is a further object of the invention to provide a method of operating a fold linkage in accordance with an embodiment of the invention. 
     In accordance with a first aspect of the invention, a conveyor includes a foldable conveyor section that is foldable with respect to a main conveyor section. The foldable and main conveyor sections are hingedly attached to each other via a fold linkage, which includes a first hinge section that is hingedly attached to a second hinge section. The first hinge section is mounted onto the main conveyor section, and the second hinge section is mounted onto the foldable conveyor section. The fold linkage in accordance with the preferred embodiment includes a pair of pressure operated cylinders disposed on opposite sides of the fold linkage, each of which includes corresponding pistons that are extendable and retractable so as to actuate a plurality of linkage members to rotate the second hinge section relative to the first hinge section. Extension of the pistons thereby rotates the foldable conveyor section from an unfolded position to a folded position to facilitate transport of the conveyor. The foldable conveyor section becomes unfolded, thereby rendering the conveyor operational, when the pistons are retracted. Advantageously, the rods of the cylinders are protected from potential hazards during operation of the conveyor. 
     In accordance with another aspect of the invention, the first and second hinge sections are rotatably attached to one another, and are further rotatably attached to the linkage members associated with the fold linkage. Furthermore, the linkage members are not connected to the truss members. Moreover, the linkage members do not extend through the truss frame. As a result, the fold linkage in accordance with an embodiment of the invention may be preassembled into a fixture prior to being mounted onto the conveyor. 
     In accordance with another aspect of the invention, the link members in accordance with an embodiment of the invention are rotatably attached to other link members or to a hinge section. As a result, the link members are not attached to the truss members of the conveyor frame. Accordingly, the truss members do not require modification in order to accommodate the fold linkage. 
     In accordance with another aspect of the invention, the foldable conveyor section includes a conventional hopper that is disposed at an end of the section opposite the end that is connected to the main section. In order to protect the hopper or other conveyor or fold linkage members from damage when the foldable conveyor section is folded, the cylinders include a relief valve that is operable to limit the amount of pressure that is accumulated within the cylinders once the pistons extend to a predetermined distance. The limited pressure within the cylinders correspondingly limits the force that causes the pistons to extend, thereby limiting the force with which the foldable conveyor section is biased towards the main conveyor section. The fold linkage and conveyor section are thereby protected from potential damage. 
     In accordance with another aspect of the invention, a method of assembling a fold linkage in accordance with an embodiment of the invention includes rotatably connecting a first hinge section to a second hinge section. A pair of hydraulic cylinders is rotatably connected to the first hinge section at one end, and to a corresponding pair of pivot arms at a second, opposite end. The pivot arms are also rotatably connected to the first conveyor section at another location, and to a corresponding pair of link arms at still another location. The pair of link awns is rotatably connected to the second hinge section. The first and second hinge sections are mounted onto the main and foldable conveyor sections, respectively. 
     In accordance with another aspect of the invention, a method of operating a fold linkage in accordance with an embodiment of the invention includes extending the pistons of the pressure operated cylinders when the conveyor is in an unfolded position. Extending the pistons folds the foldable conveyor section about the main conveyor section until the conveyor is folded for transport. Likewise, to unfold the conveyor, the pistons are retracted to unfold the foldable conveyor section about the main section so as to render the conveyor operational. 
     Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and the accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
     FIG. 1 is a side elevation view of a conveyor having a fold linkage in constructed in accordance with a preferred embodiment of the invention; 
     FIG. 2 is a side elevation view of the fold linkage of FIG. 1; 
     FIG. 3 is a side elevation view of the conveyor and fold linkage of FIG. 2 showing the conveyor in a partially folded position; 
     FIG. 4 is a side elevation view of the conveyor and fold linkage of FIG. 3 showing the conveyor in a folded position; 
     FIG. 5 is an exploded perspective view of the fold linkage of FIG. 2 being assembled in accordance with the preferred embodiment; 
     FIG. 6 is a side elevation view of a conveyor having a fold linkage in accordance with the preferred embodiment and a fold linkage in accordance with an alternate embodiment; and 
     FIG. 7 is a schematic illustration of a pressure operated cylinder having a relief valve in accordance with an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Pursuant to a preferred embodiment of the invention, a fold linkage includes a first hinge section that is rotatably connected to a second hinge section. A plurality of linkage members is rotatably connected to the hinge sections and to one another via respective joints. A pair of fluid pressure operated cylinders and corresponding pistons are operable to permit the second hinge section to be rotated relative to the first hinge section. The first hinge section is mounted onto the top of a main conveyor section of a conveyor, and the second hinge section is mounted onto the top of a foldable conveyor section, which is rotatably connected to the main conveyor section. The foldable conveyor section is unfoldable with respect to the main conveyor section to permit operation of the conveyor, and is foldable to allow the conveyor to be easily transported. Advantageously, the fold linkage is modular and may be preassembled into a fixture before being mounted onto the conveyor. Furthermore, the joints are arranged so as to avoid interference with the conveyor and its associated truss members when the fold linkage is mounted. 
     Referring initially to FIG. 1, a conveyor assembly  20  includes a conveyor frame  22  that is supported by truss members  24 . An endless conveyor  26  surrounds a plurality of rollers  28 , which are attached to the conveyor frame  22 . Additionally, a hopper  29  is located at one end of the conveyor assembly  20 , as is well known in the art. The assembly  20  includes a main conveyor section  38  and a foldable conveyor section  40 , which is foldable from the operating position A to the transport position B via a fold linkage  42 , shown in FIG.  1 . While the fold linkage  42  is preferably formed from steel, any other suitable material may be used in accordance with the preferred embodiment. 
     When in the operating position, the conveyor assembly  20  is supported by a undercarriage assembly  32  and a support  36 . When the assembly  20  is to be transported, a releasable brake mechanism  34  is released, which allows the conveyor to be transported via wheels  30 , as is well known in the art. 
     Referring now also to FIGS. 2 and 5, the conveyor frame  22  includes an upper frame member  44  and a lower frame member  46 . The fold linkage  42  comprises a first hinge section  48  that is mounted onto the top of the main conveyor section  38  via a conventional welding operation, and a second hinge second  50  that is mounted onto the top of the foldable conveyor section  40  also via welding. While welding is used in accordance with the preferred embodiment, it should be appreciated that any other suitable method and apparatus could be used. The hinge sections  48  and  50  include a plurality of support members  51 , and a corresponding pair of generally triangular flanges  53  that are rotatably connected to each other as will be described in further detail below. The first hinge section  48  further includes a rear plate  55  having a corresponding pair of flanges  58  disposed on an outer edge of the rear support plate. The main conveyor section  38  and foldable conveyor section  40  include reinforcing plates  110  that are located at joint  43 . 
     The first and second hinge sections  48  and  50  include holes  52  and  54  (FIG.  5 ), respectively, that are aligned and that are secured via pins  56 . A fluid pressure operated cylinder and corresponding piston, comprising a hydraulic cylinder  62  and rod  88  in the preferred embodiment, includes a flange  64  having opening  66  that mates with a corresponding hole  60  on flange  58  to attach the cylinder to the hinge section  48  via a locking pin  68 . The cylinder  62  is thereby rotatably connected to the hinge section  48 . The size of the hinge sections  48  and  50  are designed in accordance with the size of the conveyor section to which they are attached in order to accommodate the stresses associated with operation. 
     While the fold linkage  42  includes two sets of linkage members that are generally aligned with each other and disposed on opposite sides of the hinge sections  48  and  50 , only one set will be described in detail. 
     The fold linkage  42  further includes a pivot arm  70  having first, second, and third joints  72 ,  74 , and  76  respectively. Joint  72  includes a generally cylindrical sleeve  78  that is mounted onto ends of a pivot shaft  80  that extends through the hinge section  48 . A keeper  82  is then attached to the ends of the pivot shaft  80  to secure the rotatable connection of the pivot arm  70  to the hinge section  48 . The pivot arm  70  includes a flange  84  having a generally circular opening  86  to partially form the second joint  74 . The hydraulic cylinder  62  includes an extendible rod  88  having a coupler  90  that includes holes  92  that mate with opening  86 . A pin  94  is inserted through the holes  92  and  86  to rotatably connect the pivot arm  70  to the hydraulic cylinder  62 . 
     A link arm  96  is rotatably connected to the hinge section  50  via a generally cylindrical sleeve  98  and ends of a corresponding pivot shaft  100 . A keeper  102  is attached to the pivot shaft  100  to secure the connection. The link aim  96  further includes a coupler  104  that mates with a generally cylindrical opening  108  of the third joint  76 . A locking pin  106  is inserted into the coupler  104  and corresponding opening  108  to secure the rotatable connection of the pivot arm  70  to the link arm  96 . Advantageously, because the fold linkage  42  is mounted to the upper frame member  44 , the truss members require no modification to accommodate the fold linkage. Additionally, the fold linkage  42  may be preassembled before being mounted onto the conveyor  20 . 
     Referring to FIG. 2, the fold linkage  42  is shown as being in an unfolded position when the rod  88  of the hydraulic cylinder  62  is in a retracted position. In operation, as the cylinder rod  88  extends as shown in FIG. 3, the pivot arm  70  rotates about the first joint  72 , thereby biasing the link arm  96  to rotate the hinge section  50  and corresponding foldable conveyor section  40  about joint  43  towards the folded position relative to the main conveyor section  38 . Therefore, when the cylinder rod  88  is in an extended position, as shown in FIG. 4, the assembly  20  is fully folded, thereby enabling the conveyor to be transported. Likewise, the rod  88  is retracted to rotate the foldable conveyor section  40  to the unfolded position (FIG. 2) thereby rendering the conveyor assembly  20  operational. Advantageously, the rod  88  is retracted during operation of the cylinder, thereby protecting it from potential hazards. 
     Referring now also to FIGS. 6 and 7, the hydraulic cylinder  62  includes a three-way valve assembly  117  that, when in an “extend position”  118 , supplies pressure to the hydraulic cylinders  62  from a source  114 . When the valve assembly  117  is in a “lock position”  120 , the pressure within the cylinders  62  will remain constants thereby locking the position of rods  88 . When the valve assembly  117  is in a “retract position”  122 , the fluid within the cylinders  62  will return to a tank  116  to reduce the pressure within the cylinders  62  and retract the rods  88 . 
     The valve assembly further includes check valves  119  that prevent the release of fluid due to the forces associated with folding and unfolding the foldable conveyor section  40 . For example, as the foldable conveyor section  40  is being folded past the “half-way” point (FIG.  3 ), the forces associated with gravity acting on the relatively large conveyor section could cause the valve assembly  117  to fail. The check valve  119  resists the fluid pressure that results from these forces, and ensures that the valve assembly  117  will be able to accommodate a full folding and unfolding operation without undergoing failure. In operation, as is well known in the art, a variable-resistance spring element acts in conjunction with a pilot pressure to either permit or restrict fluid flow through the check valve. When closed, the valve will permit only unidirectional fluid flow from the source  114  to the cylinder  62 . 
     The valve assembly  117  may also include a relief valve  112  to accommodate the hopper  29 . More specifically, the relief valve  112  allows pressure to escape from the cylinder  62  once the rod  88  has extended beyond a predetermined distance. The amount of permitted extension will be limited by the limited amount of permissible folding of the foldable conveyor section  40  in order to compensate for the hopper  29 . Once the folding is completed, the rod  88  will be extended beyond the location of the relief valve  112 . The relief valve  112  then activates, and the pressure within the cylinder  62  is limited. The limited pressure within the cylinder  62  correspondingly limits the amount of force applied to the members of the fold linkage  42  and the conveyor assembly  20 ′ when the foldable conveyor section  40  is folded. For example, the amount of force that is supplied by the cylinder  62  when the rod  88  is extended beyond the location of the relief valve  112  may be a fraction of the force that is supplied before the rod  88  is extended beyond the location of the relief valve. The relief valve  112  thereby protects the hopper  29  and other members of the fold linkage  42  and conveyor assembly  20 ′ from potential damage. 
     When the valve assembly  117  is in the “extend position”  118  and the rod  88  is extended beyond a predetermined distance, the relief valve will operate to allow pressure within the cylinder to escape into the tank  116 . The amount of force with which the foldable conveyor section  40  is being biased against the main conveyor section is thereby limited. A stop  124  may also be attached to the main conveyor section  38  to support the foldable conveyor section  40  when it is in the folded position. 
     While the valve assembly has been described in accordance with an embodiment of the invention, it should be appreciated that other suitable arrangements incorporating a relief valve may be used. 
     Many other changes and modifications may be made to the invention without departing from the spirit thereof. The scope of the changes will become apparent from the appended claims.