Abstract:
An overhead conveyor, components therefor and method for making same, in which the conveyor trolley utilizes load wheels having double row bearings, and is designed for a channel having a height “X,” but is built with a maximum allowable load value which is equal to or greater than the maximum allowable load value for a trolley used in channels of height greater than X.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
       [0001]    The present application claims priority to U.S. Provisional application Ser. No. 61/747,172, filed Dec. 28, 2012, entitled  HIGH CAPACITY CONVEYOR TROLLEY AND METHOD , and U.S. Provisional application Ser. No. 61/764,774, filed Feb. 14, 2013, entitled  HIGH CAPACITY CONVEYOR TROLLEY AND METHOD.    
     
    
       [0002]    The present invention relates to overhead conveyors, which typically comprise at least an “I-beam” track  1 , trolleys  2  which have opposed wheels  3  engaging the bottom flanges of said I-beam track  1  on opposite sides of the center web of the beam, and a driven conveyor chain (not shown) connected to said trolleys at spaced intervals ( FIG. 1 ). The chains usually comprise center links alternating with a pair of side links, which overlap the end of the center link on the opposite sides thereof, and are joined to the center link by a pin passing through the overlapping ends of the side links and center links. When the trolleys are thus driven by a chain, they are referred to as power trolleys. 
         [0003]    While power trolleys are sometimes used directly to convey whatever items are being processed, they are more typically used to drive free trolleys  10 , which travel freely on paired, laterally spaced load wheels  20  running on the lower flanges  41  of spaced inwardly facing “C” shaped tracks  40 . Two horizontally oriented guide wheels  30  at the bottom of each free trolley are positioned between the C channel flanges  41 , to help keep trolley  10  from shifting too far to the right or left as they travel in tracks  40 . 
         [0004]    The C channel tracks are supported by a pair of support arms  5 , mounted atop the I-beam  1  and depending downwardly past either side thereof and past either side of the power trolleys. Downwardly depending pushers (not shown) are mounted on either the power trolleys  1  or the chain carried by and driving the power trolleys, for engaging dogs  11  on the free trolleys, to thereby move the free trolleys  10  along in their tracks  40 . When it is desired to stop a trolley, mechanisms are provided for retracting either the pushers or the dogs  11 , so that the trolley stops. The so called free trolleys thus carry the heavy loads which are to be moved from place to place. The trolley and “C” track arrangement can be used as powered trolleys driven by a drive chain. However, this arrangement is typically used as a set of free trolleys. 
         [0005]    In accordance with long standing industry practice, trolleys are numbered in accordance with the approximate height of the I-beam or C channel tracks they are carried on. Industry standards, and longstanding industry practice call for 3 inch tracks, 4 inch tracks and 6 inch tracks. Thus, there have long been 3 inch trolleys, 4 inch trolleys and 6 inch trolleys. 
         [0006]    Also by long recognized industry standards, the so called free trolleys (which can be driven) are built to carry heavier loads than the so-called driven trolleys. The free trolleys come in a standard grade and a heavier grade for carrying heavier loads. These loads are in accordance with long recognized standards. Thus the heavy load capacities for 3, 4 and 6 inch free trolleys are: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 3 inch free trolley 
                   800 # 
               
               
                   
                 4 inch free trolley 
                 2,000 # 
               
               
                   
                 6 inch free trolley 
                 4,000 # 
               
               
                   
                   
               
             
          
         
       
     
       SUMMARY OF THE INVENTION 
       [0007]    The present invention comprises an overhead conveyor, components therefor and method for making same, in which the conveyor trolley is designed for a channel having a height “X,” but is built with a maximum allowable load value which is equal to or greater than the maximum allowable load value for a trolley used in channels of height greater than X. The trolley of the present invention utilizes load wheels having double row bearings. 
         [0008]    This surprising departure from industry standards makes it possible to use, for example, four inch trolleys and four inch tracks, to care a load normally requiring six inch trolleys and six inch tracks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a lateral cross sectional view of a prior art power and free trolley arrangement; 
           [0010]      FIG. 2  is a lateral cross sectional view of a power and free trolley arrangement made in accordance with a preferred embodiment of the invention; 
           [0011]      FIG. 3  is a side perspective view of a four inch trolley in accordance with the preferred embodiment, with the dog mechanism not shown; 
           [0012]      FIG. 4  is a top plan view of view of a lour inch trolley in accordance with the preferred embodiment, with the dog mechanism not shown; 
           [0013]      FIG. 5  is a lateral cross sectional view of double row bearing wheel for use as a load wheel in a preferred embodiment trolley; 
           [0014]      FIG. 6  is a side elevational view of the wheel of  FIG. 5 ; 
           [0015]      FIG. 7  is an exploded cross sectional view of a double row bearing wheel for use as a load wheel in a preferred embodiment trolley. 
           [0016]      FIG. 8  is a lateral cross sectional view of double row bearing wheel for use as a guide wheel in a preferred embodiment trolley. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    Trolleys  10   a  of the preferred embodiment comprises a pair of spaced side plates  50   a  joined by bolts  51   a  ( FIGS. 3 and 4 ). A pair of load wheels  20   a  are mounted to each side plate  50   a , facing outwardly from each side of trolley  10   a . Load wheels  20  a travel on the bottom flanges  41   a  of channel shaped tracks  40   a  ( FIG. 2 ). Guide wheels  30   a  are mounted on vertically oriented axels, located between side plates  50   a  ( FIGS. 2-4 ). Guide wheels  30   a  project beyond side plates  50   a  on each side of trolley  10   a , and have an outside diameter just slightly less than the space between the inwardly facing, spaced edges of the bottom flanges  41   a  of opposed channel tracks  40   a . Dogs  11   a  are retractable by a conventional mechanism, such that trolleys  10   a  can be disengaged from pushers mounted on the power trolleys  2  or on the power chain carried by and driving the power trolleys  2 . 
         [0018]    Instead of a single row of bearing wheels conventionally used in conveyor trolleys, load wheels  20   a  have a doable row of bearings  22   a  and  22   b , positioned next to and parallel to one another within the confines of wheel  20   a  ( FIGS. 5 and 7 ). Bearings  22   a  are located in the inside, or proximate row of bearings, that is the row facing a trolley side plate  50   a , while bearings  22   b  are located in the outside, or distal row of bearings which faces away from a trolley side plate  50   a . This additional row of bearings significantly increases the overall load capacity of load wheel  20   a . Each wheel  20   a  is formed on its interior to define an inwardly opening proximate outer race  21   a  and an outwardly opening distal outer race  21   c , separated by a shared outer race wall  21   b . A proximate inner race defining ring  23   a  and a distal inner race defining ring  23   b  are inserted into wheel  20   a  from opposite sides, so as to abut one another and trap the bearings  22   a  between the inner races  23   a  and  b , and the outer races,  21   a  and  b , respectively. Inner race rings  23   a  and  b  are carried on hub  27 , which includes an inside lip  27   a , which locks proximate inner race  23   a  in place when the components are assembled. A similar outer lip  27   b  is then swaged on the outside edge of hub  27  to lock distal inner ring  23   b  in place. The interior of hub  27  has a diameter to accept a wheel axel which is at least 25% greater than the standard ⅝ inch axel of prior art-trolley wheels, more preferably 50% greater (¾ to 1 inch in diameter). Hub covers  25  and  26  cover the opposite sides of each load wheel  20 . 
         [0019]    As can be seen by comparing the prior art trolley of  FIG. 1  to the preferred embodiment trolley of  FIG. 2 , the outer tracking surface of each preferred embodiment load wheel is wider than the tracking surface on the prior art wheels on a correspondingly sized trolley. Specifically,  FIG. 2  shows the preferred embodiment wheel tracking surface to be 100% wider than the tracking surface of prior art wheels on a correspondingly sized trolley. 
         [0020]    The trolley wheels  22   a  of the preferred embodiment are also preferably from 5 to 20%, more preferably from 10 to 15% less in mean outside diameter than the standard 2.4 inch diameter wheels used on 3 inch trolleys (i.e. 1.9-2.3, preferably 2.0-2.2 inches instead of 2.4), and the standard 3.2-3.3 inch diameter wheels used on the 4 inch (i.e. 2.5-3.0, preferably 2.7-2.9 inches) and the standard 4.0-5.25 inch wheels used on 6 inch trolleys (i.e. 3.2-3.8 inches, preferably 3.4-3.6 inches). The use of smaller outside diameter wheels is surprisingly made possible by the use of double row bearings. The decreased size of the load wheel allows for the use of smaller C-channels, saving significant materials. 
         [0021]    The trolley guide wheels  30   a  also preferably employ a double row of bearings  32   a  and  b , which significantly increase the overall load capacity of the wheel. ( FIG. 8 ) For purposes of discussion, bearings  32   a  are proximate, facing up toward the bottom of trolley  10   a . Bearings  31   b  are distal, and will face down away irons the bottom of trolley  10   a , when the guide wheels are installed. The guide wheels  30   a  axe of similar construction to the load wheels, except that the exterior of the guide wheel itself arcs outwardly slightly from side to side. In contrast, load wheels  22   a  have generally flat outer surfaces, inclined slightly to match the incline of the track flanges  41   a  on which they ride. 
         [0022]    Each wheel  30   a  is formed on it interior to define an inwardly opening proximate outer race  31   a  and an outwardly opening distal outer race  31   b , separated by a shared outer race wall  31   c . A proximate inner race defining ring  33   a  and a distal inner race defining ring  33   b  are inserted into wheel  30   a  from opposite sides, so as to abut one another and trap the bearings  32   a  between the inner races  33   a  and  b , and the outer races,  31   a  and  b , respectively, inner race rings  33   a  and  b  are carried on hub  37 , which includes an inside lip  37   a , which locks proximate inner race  33   a  in place when the components are assembled. A similar outer lip bob is then swaged on the outside edge of hub  37  to lock distal inner ring  33   b  in place. 
         [0023]    The two substantially parallel side-plates  50   a  are connected preferably by at least grade 8 bolts  51   a , rather than by grade 5 bolts as are conventionally uses. These plates are preferably at least 15% thicker than prior art ⅜ inch thick trolley side-plates, and more preferably, at least 25% greater ( 7/16 to ½ of an inch). 
         [0024]    In a preferred embodiment, the channel strengths as determined by pounds of material per foot of track, are 50-75% greater than standard strengths. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Trolley 
                 CEMA Strength 
                 Preferred 
               
               
                   
                 Channel 
                 Standards 
                 Embodiment Strengths 
               
               
                   
                   
               
             
             
               
                   
                 3″ I-Beam 
                 5.7 lbs/foot 
                   8.5-10 lbs/foot 
               
               
                   
                 4″ I-Beam 
                 7.7 lbs/foot 
                 11.5-13.5 lbs/foot 
               
               
                   
                 6″ I-Beam 
                 12.5 lbs/foot  
                 18.7-21.8 lbs/foot 
               
               
                   
                 3″ C- 
                 4.1 lbs/foot 
                  6.1-7.2 lbs/foot 
               
               
                   
                 Channel 
               
               
                   
                 4″ C- 
                 5.4 lbs/foot 
                  8.1-9.5 lbs/foot 
               
               
                   
                 Channel 
               
               
                   
                 6″ C- 
                 10.5 lbs/foot  
                 15.7-18.4 lbs/foot 
               
               
                   
                 Channel 
               
               
                   
                   
               
             
          
         
       
     
         [0025]    The benefits of the present invention have not at ail been recognized or thought of by prior artisans. The use of at least double-row bearings in the load and guide wheels significantly increases the load capacity of the trolley without increasing the size of the trolley or track. This allows, for instance, loads traditionally carried only by a 6-inch trolley on a 6-inch track to be carried on a 4-inch track and trolley. Further reduction to the amount of materials needed for tracks is achieved by reducing the axial height of the load wheels. 
         [0026]    For example, one 4 inch trolley has been load tested to 23,800 pounds without breakage. The preferred embodiment trolleys can he comfortably rated to twice the standard loads given for prior art trolleys of the same size: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Prior Art Load 
                 Preferred Embodiment 
               
               
                   
                 Free Trolley Size 
                 Rating 
                 Load Rating 
               
               
                   
                   
               
             
             
               
                   
                 3 inch free trolley 
                   800 # 
                 1600# or higher 
               
               
                   
                 4 inch free trolley 
                  2000 # 
                 4000# or higher 
               
               
                   
                 6 inch free trolley 
                 4,000 # 
                 8000# or higher 
               
               
                   
                   
               
             
          
         
       
     
         [0027]    Other embodiments of the invention are contemplated by the inventor.