Abstract:
A slide-bearing assembly capable of enabling sliding of a load-carrying surface relative to a load-supporting structure, such that the slide-bearing assembly may include a first arrangement of at least one substantially nonmetallic elongate bearing element capable of extending along a first load-carrying surface and a second arrangement of at least two substantially nonmetallic elongate bearing elements capable of extending longitudinally in series along a second load-carrying surface parallel to the first load-carrying surface such that the second load-carrying surface is in non-coextensive supportive relationship with the first load-carrying surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter of this application relates to a slide bearing system useable with a load-handling or carrying system and a corresponding load-supporting structure, such as used with a lift truck. The combination of a load-handling system and a load-supporting structure often includes surfaces that continuously slide against one another. Continuous movement leads to wear and damage to the interface parts, thus requiring frequent repair or replacement of expensive parts. Depending on the materials present at the interface, such movement may also create enhanced frictional heat at the interface which can cause damage to other non-heat-resistant components, and also may require increased energy output from the lift truck to create movement at the interface 
         [0002]    Nonmetallic materials such as nylon have been used as bearings where only a single bearing is attached to one moving surface, thereby leaving the opposing surface exposed. With the use of only a single nonmetallic bearing, the single bearing normally slides against a steel surface of the opposing load carrying component, causing a high rate of wear. 
         [0003]    Conversely, as will be discussed in detail herein, the use of plastic bearings on both opposing load-carrying surfaces results in lower wear and lower forces required to move a load and thereby reduce the energy consumption of the operation. 
       SUMMARY OF THE INVENTION 
       [0004]    In one embodiment, the invention described herein may include a slide-bearing assembly capable of enabling sliding of a load-carrying implement relative to a load-supporting structure, such that the slide-bearing assembly includes substantially nonmetallic first and second opposing elongate bearing elements capable of extending in parallel to support the load-carrying implement slidably upon the load-supporting structure. The embodiment may be advantageously constructed so that one of the bearing elements is composed of multiple elongate pieces, each shorter in length than the length of the other of the bearing elements. 
         [0005]    In another embodiment, the invention described herein may include a slide-bearing assembly capable of enabling sliding of a load-carrying surface relative to a load-supporting structure, such that the slide-bearing assembly may include a first arrangement of at least one substantially nonmetallic elongate bearing element capable of extending along a first load-carrying surface and a second arrangement of at least two substantially nonmetallic elongate bearing elements capable of extending longitudinally in series along a second load-carrying surface parallel to the first load-carrying surface such that the second load-carrying surface is in non-coextensive supportive relationship with the first load-carrying surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: 
           [0007]      FIG. 1  is a sectional view of a J-plate assembly. 
           [0008]      FIG. 2  is a sectional view of an upper arm assembly. 
           [0009]      FIG. 3  is a sectional view of a lower arm assembly. 
           [0010]      FIG. 4  is a plan view of an upper hook bearing. 
           [0011]      FIG. 5  is a sectional view of the upper hook bearing shown in  FIG. 4 , 
           [0012]      FIG. 6  is a top plan view of a J-plate bearing. 
           [0013]      FIG. 7  is a side plan view of the J-plate bearing shown in FIG,  6   
           [0014]      FIG. 8  is a sectional view of the J-plate bearing shown in  FIG. 6 . 
           [0015]      FIG. 9  is a plan view of a primary T-bar bearing. 
           [0016]      FIG. 10  is a side plan view of the primary T-bar bearing shown in  FIG. 9 . 
           [0017]      FIG. 11  is a plan view of a secondary T-bar bearing. 
           [0018]      FIG. 12  is a side plan view of the secondary T-bar bearing shown in  FIG. 11 . 
           [0019]      FIG. 13  is a plan view of a tertiary T-bar bearing. 
           [0020]      FIG. 14  is a side plan view of the tertiary T-bar bearing shown in  FIG. 13 . 
           [0021]      FIG. 15  is a plan view of a primary C-channel bearing. 
           [0022]      FIG. 16  is a side plan view of the primary C-channel bearing shown in  FIG. 15 . 
           [0023]      FIG. 17  is a plan view of a secondary C-channel bearing. 
           [0024]      FIG. 18  is a side plan view of the secondary C-channel bearing shown in  FIG. 17 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring now to the drawings which form a part of the disclosure herein,  FIGS. 1, 2 and 3  are sectional views of bearings assembled with a load-supporting structure such as a lift truck. In one embodiment,  FIG. 1  shows a sectional view of a bearing on bearing assembly associated with a translating upper hook  12  and a non-translating or stationary J-plate  14 , referred to together as the J-plate assembly  10 . 
         [0026]    In another embodiment,  FIGS. 2 and 3  show sectional views of different respective upper  18  and lower  20  bearing on bearing channel assemblies for translating arms or carriers. These two different channel assemblies are referred to in combination as the arm assembly  16 . 
         [0027]    In the embodiment shown in  FIG. 1 , the J-plate assembly  10  includes a single upper hook bearing  22  attached to a load-carrying surface of the translating upper hook  12 . Plan and sectional views of the upper hook bearing  22  are shown in  FIGS. 4 and 5 . Attached to a second load-carrying surface of the non-translating J-plate  14  are J-plate bearings  24 , shown in detail in  FIGS. 6, 7 and 8 . The first and second load-carrying surfaces are at least substantially parallel to one another. 
         [0028]    As best viewed in  FIGS. 4 and 5 , the upper hook bearing  22  may be constructed with one or more posts  48 ,  49 . Each such post  48 ,  49  is sized and shaped to fit in one or more recesses within a load-bearing surface of the translating upper hook  12  to stabilize and secure the upper hook bearing  22  to the upper hook  12 . Therefore, in use, as the translating upper hook  12  moves in a transverse direction, the upper hook bearing  22  remains secured to the translating upper hook  12  and slides against the J-plate bearing  24 . 
         [0029]    The embodiment of the upper hook bearing  22  together with the J-plate bearing  24 , shown in  FIGS. 1, 4 and 5 , may have a self-lubricating, greasable interface with the use of at least one grease supply fitting  44 , such as a Zerk fitting, located within a post  48 , and a corresponding grease pathway  50  in the J-plate bearing  24 . Self-lubricating bearings remove the need for maintenance because they do not need to be frequently changed or cleaned. Zerk fittings, as shown in the embodiment in  FIG. 1 , communicate with grease pathways  50  in the bearing surface to improve efficiency of translating movement by using grease between the bearings to further reduce friction. Grease can be applied at regular intervals with the use of a grease gun (not shown). The grease fills pathways  50  in the surface of the lower bearings (in the present embodiment, the J-plate bearing  24 ) that spread the grease over the interface between the bearings. 
         [0030]    In one non-limiting exemplary embodiment, the upper hook bearing  22  used may be approximately  620  millimeters in length. The J-plate bearing  24  may be approximately  200  millimeters in length. In an assembly as shown in  FIG. 1 , two J-plate bearings  24  may be secured to the stationary J-plate  14  end-to-end in a transverse direction, and one upper hook bearing  22  may be secured to the translating upper hook  12  in the same direction. Accordingly, there may be an end-to-end gap between the two J-plate bearings  24 . The configuration of the dual J-plate bearings  24  may be referred to as a single elongate bearing element composed of multiple elongate pieces. Depending on manufacturer&#39;s specifications, the upper hook bearing  22  and the J-plate bearing  24  may have different lengths. The depths and widths of individual bearings may be uniquely selected based on manufacturer specifications as well. In one embodiment, the length of the upper hook bearing  22  will be longer than the length of the dual J-plate bearings  24  because the translating upper hook  12  has a transverse width greater than the width of the stationary J-Plate  14 . Such a configuration avoids the potential issue of having a bearing being completely disengaged during the translational motion between the translating upper hook  12  and the stationary J-Plate  14 . 
         [0031]    The alternative embodiment shown in  FIG. 2  illustrates an upper assembly for translating arms/carriers  18 , and the primary C-channel bearings  28  are attached to a load carrying surface of upper C-channel  26 . Plan and sectional views of an exemplary embodiment of the primary C-channel bearing  28  are shown in  FIGS. 15 and 16 . Secondary C-channel bearings  30  are attached to the load carrying surface of upper C-channel  26  as well. Plan and sectional views of an exemplary embodiment of the secondary C-channel bearing  30  are shown in  FIGS. 17 and 18 . Partially encompassed by the upper C-channel  26  is an upper translating T-bar  32 . Both a primary T bar bearing  34  and a secondary T bar bearing  36  are attached to the load carrying surface of upper T-bar  32 , as best viewed in  FIG. 2 . The plan and sectional views of primary and secondary T-bar bearings  34  and  36  are shown in  FIGS. 9 and 10  and  FIGS. 11 and 12 , respectively. 
         [0032]    In one non-limiting exemplary embodiment, the primary C-channel bearing  28  may be approximately 334 millimeters. Two primary C-channel bearings  28  may be secured to the upper C-channel  26  in a transverse direction. The secondary C-channel bearing  30  may also be approximately 334 millimeters. Two secondary C-channel bearings  30  may be secured to the upper C-channel  26  in series or in a transverse direction. The primary T-bar bearing  34  may have a length of approximately 265 millimeters. The secondary T-bar bearing  36  may have a length of approximately 265 millimeters. In other embodiments, the bearings described herein may be of other lengths. The other dimensions of the bearings, such as the depth and width, may be selected based on manufacturer specification. In this embodiment, the lengths of the primary and secondary T-bar bearings  34 ,  36  are limited by the transverse width of the upper T-bar  32 . 
         [0033]    In the embodiment of the lower assembly for translating arms/carriers  20 , two primary C-channel bearings  28  are attached to a load carrying surface of the lower C-channel  38 . Primary C-channel bearings  28  are attached on the top and bottom parts of load-carrying surfaces of the lower C-channel  38 , as best viewable in  FIG. 3 . Partially encompassed by the lower C-channel  38  is a lower translating T-bar  40 . A pair of primary T-bar bearings  34  are attached to a load carrying surface of one side of the lower translating T-bar  40 . A pair of tertiary T-bar bearings  42  are attached to a load carrying surface one side of the lower translating T-bar  40 . 
         [0034]    Primary C-channel bearings  28  and secondary C-channel bearings  30  may also include posts  52 ,  55  which extend out of the bearings  28 ,  30  into corresponding spaces in the load-carrying surface of the upper C-channel  26 , as best viewable in  FIG. 2 . Primary T-bar bearing  34  and tertiary T-bar bearings  42  may also be constructed with posts  54 ,  56 , respectively. Secondary T-bar bearing  36  includes rectangular bearings  58 . 
         [0035]    In one non-limiting exemplary embodiment, the primary C-channel bearing  28  may be approximately 334 millimeters. Two primary C-channel bearings  28  may be secured to the lower C-channel  38  in series or in a transverse direction. The primary T-bar bearing  34  may have a length of approximately 265 millimeters. The tertiary T-bar bearing  42  may have a length of approximately 265 millimeters. The other dimensions of the bearings, such as the depth and width, may be selected based on manufacturer specification. In this embodiment, the lengths of the primary and tertiary T-bar bearings  34 ,  42  are limited by the transverse width of the lower T-bar  40 . 
         [0036]    Such assembly embodiments  10 ,  16  may have load bearing surfaces with multiple shorter bearing sections positioned in series, along the width of a load-supporting structure such as a side shifter, in slidable contact with a longer bearing section. An advantage of having multiple shorter bearings is that a manufacturer may accommodate a wide range of side shifter widths by using multiples of the small support bearings. The lengths of the bearings may be selected so that the bearing lengths manufactured accommodate the widths of a variety of frame widths, thereby avoiding the need to manufacture new bearings at different lengths for each different frame width. Therefore, a manufacturer would be able to reduce the number of unique bearings it would need to produce. 
         [0037]    In one embodiment of the invention, the bearings ( 22 ,  24 ,  28 ,  30 ,  34 ,  36 ,  42 ) may have chamfered ends. An assembly, however, for example the J-plate assembly  10 , may include bearings that have both chamfered, partially chamfered and non-chamfered ends. Chamfered ends may be beneficial in such assemblies  10 ,  16  by minimizing the potential of non-chamfered or otherwise cornered ends from one bearing getting caught with an end of another bearing during use. 
         [0038]    In some embodiments of the present invention, the bearings are substantially non-metallic. In some embodiments, the stationary bearings are nylon 6/6, 10% Aramid Fiber, 15% PTFE. In some embodiments, the translating bearings are nylon 6/6, 30% carbon fiber, 15% PTFE. Such bearings may also be made out of ceramic materials. 
         [0039]    It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims, as interpreted in accordance with principles of prevailing law, including the doctrine of equivalents or any other principle that enlarges the enforceable scope of a claim beyond its literal scope. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated. The word “comprise” or a derivative thereof, when used in a claim, is used in a nonexclusive sense that is not intended to exclude the presence of other elements or steps in a claimed structure or method.