Abstract:
A chain and hydraulic motor-driven low dog railcar indexer is disclosed which is operable along a curved track section. The system includes left and right track side indexing railcar-moving arrangements, each of which includes an indexer track and a chain-return trough. The indexer tracks and chain return troughs are segmented to accommodate the curved railroad track section and wear pads are provided to enable chain operation in the curved section.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
       [0001]    Not applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    I. Field of the Invention 
         [0004]    The present invention relates generally to trackside railway car handling equipment for positioning railcars along a track for loading or unloading operations. More particularly, the present invention relates to a train positioning system that employs a design that enables it to be operable along a section of curved tracks. The system uses two dog carriages and operates as an indexer against the bogey frames of railcars. 
         [0005]    II. Related Art 
         [0006]    Freight-hauling railway cars need to be precisely positioned proximate freight or cargo handling equipment during loading and unloading operations. Freight in the form of bulk cargo such as grain is typically loaded or unloaded with reference to stationary freight handling equipment such as chutes and conveyor equipment situated at fixed locations above or in pits beneath a specific portion of the track. Railcars for transporting grain or other such finely divided dry bulk agricultural commodities may be covered and designed with a plurality of spaced bottom discharge hopper bins or chutes accessing the main cargo storage volume. The chutes are closed by capstan-operated rack and pinion bottom closure gate systems. 
         [0007]    In the loading and discharge operations, a connected engine roughly positions one end of a string of cars to be loaded or unloaded beneath or above the appropriate equipment at the desired fixed location. Because locomotives are not well suited for precisely positioning individual cars or even strings of cars along a railroad track, positioning devices known as train movers or positioners are located at fixed stations along the track. The positioning devices generally employ heavy pushing members known as railcar-engaging “dogs” to move the cars into position. 
         [0008]    Positioning devices are generally classified in the industry as “indexers” or “progressors”. Indexers may employ dogs carried by a pair of carriages operating along indexer tracks on built-in guideways located on the outside of each of the spaced rails of an associated track. Indexers are designed so that the carriages and associate dogs located on both sides of the track are coordinated to operate together in unison to engage and move a car or string of cars along the track. Thus, in indexer type bogey frame-engaging positioning devices, dogs on dog carriages spaced on opposite sides of the track are caused to engage the bogey frame at the same time to thereby provide a balanced force by pushing against both of the spaced sides of the truck bogey frame simultaneously. 
         [0009]    Progressors designed to operate against bogey frames also operate along rails in built-in guideways on the outside of each of the spaced rails of a track with dogs that operate along each of the guideways spaced along the track. Rather than operating simultaneously against both sides of a bogey frame to move a car or string of cars, the dogs of a progressor are operated alternately against only one side of a bogey frame, to sequentially engage bogey frames so as to “hand off” the car or string of cars alternating between dogs on opposed sides of the track. 
         [0010]    Operation as an indexer advantageously provides a balanced side-to-side force on the bogey frame and enables the total force of two dog carriage systems to be applied at once so that heavier loads may be moved. This also enables a balanced force to be applied against the bogey frames of lightly loaded cars which avoids a possible tipping situation which may occur when force is applied to one side only. 
         [0011]    Heretofore, such railcar handling equipment has been constructed to operate only along sections of straight track either as an indexer or a progressor and it would provide a distinct advantage and answer a definite need in the art if such a system could be operated along a curved track section. 
       SUMMARY OF THE INVENTION 
       [0012]    By means of the present invention there is provided a railcar positioning system operable in an indexing mode along a curved track section. The system includes left and right track side indexing railcar-moving arrangements positioned just outside and parallel to flanking the rails of a railroad track having a curved aspect. Each of the left and right track side arrangements includes a guideway in the form of an indexer track which extends along outside each rail of the track. In the vicinity of the curved track section, the indexer tracks are segmented into a plurality of connected short sections that are placed at slight angles with each other so as to follow the track curve. A dog carriage is mounted on each of the spaced indexer tracks and is provided with a pair of spaced dogs designed to address the front or rear of a bogey frame in a coordinated manner. Thus, in that embodiment, the system of the invention is configured as a reversing low dog indexer. 
         [0013]    Each dog carriage of the indexer is chain and hydraulic motor driven with a dog carriage attached to both ends of a continuous chain. Wear pads are placed at every bend in the curved section as determined by angled joints between sequential short sections of the indexer tracks and associated chain return troughs. The structure may be further reinforced against chain side load forces. 
         [0014]    The segmented indexer tracks and chain return trough wear pads enable smooth operation of the chain-driven system along a curved track section. A chain and hydraulic motor-driven low dog indexer in accordance with the invention with indexer carriage dogs on both sides of the track pushing together can apply a force of about 60,000 pounds against a bogey frame and reach speeds from 25 to 90 FPM. The indexer system of the invention can accommodate said sections with a curvature of up to about 10 degrees using a plurality of short five-foot indexer track and return trough sections. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    In the drawings wherein like numerals depict like parts throughout the same: 
           [0016]      FIG. 1  is a broken schematic plan view of an indexer arrangement in accordance with the invention; 
           [0017]      FIG. 2  is an enlarged fragmentary view of the area circled in  FIG. 1 ; 
           [0018]      FIG. 3  is an enlarged fragmentary view of the area circled in  FIG. 2 ; 
           [0019]      FIG. 4  is a fragmentary perspective view of a rail and indexer carriage track similar to that shown in Figure, and; 
           [0020]      FIG. 5  is a drawing showing a dog carriage engaging a bogey frame of a railcar. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The following detailed description of the present invention describes the invention in terms of one illustrated embodiment. It will be understood that the system described is intended by way of presenting an example of the inventive concept and is not intended to limit the scope in any manner. A variation within the scope of the inventive concept may occur to those skilled in the art. 
         [0022]    In  FIG. 1  there is shown a broken schematic plan view or layout view of a segment of railroad track including an indexer arrangement in accordance with the invention. The layout, generally at  10 , depicts a section of railroad track having a curved portion and a straight portion and includes spaced parallel rails  12  and  14  flanked by indexer tracks  16  and  18 , respectively. Chain return troughs are shown at  20  and  22 . The indexer arrangement or system includes dog carriages  24  and  26  with respective hydraulic motor drive units  28  and  30  and corresponding idler units  32  and  34 . 
         [0023]    In the curved section, the indexer tracks are divided into a plurality of short segments  36  and  38 , which are shown at the outer and inner portion of the curve, respectively. The short segments may have a length of five feet. Longer, straight sections are shown at  40  and  42 . These may have a length of twenty feet. 
         [0024]    The area circled in  FIG. 1  is accommodated in the enlarged view that is  FIG. 2 . Outer curve indexer wear pads  50  are placed at the interfaces of the angled outer curve indexer track  36 , and inner curve indexer wear pads  52  are placed at the interfaces of the angled indexer track segments  38 . Outer curve wear pads  54  are placed at the interfaces of the return trough segments  40  and inner curve return trough wear pads  56  are placed at the interfaces of the angled trough sections  42 . It will be recognized that the wear pads  50  and  54  located in the indexer track and chain return trough, respectively, are placed on the inside of the corresponding track and trough inasmuch as this represents the outer portion of the curve and the chain will have the tendency to move in that direction and bear against the wear pads. Conversely, the indexer track and chain return trough wear pads  52  and  56  are located on the outer portion of the indexer track and chain return trough, respectively, as this represents the inner portion of the curve. Thus, the tendency of the chain to shift from one side or another as it negotiates the curve is compensated by the location of the wear pads which absorb side forces and enable the chain to slide past easily. Reinforcing structural members as at  58  may be added to take chain side loading that occurs in the curve. 
         [0025]      FIG. 3  is a further enlarged fragmentary view of the area circled in  FIG. 2  and shows the details of the interfaces between indexer track segments and chain return trough segments previously described. Note that the interface between the segments is slightly offset from a straight joint by 1.03 degrees. In this manner, the eight (8) curve segments shown in  FIG. 1  would accommodate cumulatively a curve of about 8.24 degrees. It is anticipated that the railcar positioning system of the invention can operate on a track having a curvature of up to at least 10 degrees. Thus, the slight offset can be about 1.2 degrees or less. The angle between the segments is commensurate with the curvature of the railroad track. 
         [0026]      FIG. 4  depicts a further enlarged fragmentary perspective view of a fragment of the layout similar to that shown in  FIG. 3  depicting a joint between segments in the outside portion of the curved section, which has been further enlarged. 
         [0027]      FIG. 5  depicts a greatly enlarged view of a dog carriage suitable for use in the indexer arrangement of the present invention and includes a dog carriage  70  with a pair of opposed dogs  72  and  74 , shown in raised relation. A nitrogen tank is shown at  76  and a coordinating connection at  78 , which raises and lowers the dogs in unison. Chain connections are shown at  80  and  82  with the connected chain  84 . The dogs are shown addressing one side of a bogey frame  86  having associated wheels  88  operating along a track rail  90 . 
         [0028]    One skilled in the art would recognize that the operation of the hydraulic drive units to advance and retract the chain to advance and retract the carriages and the coordination of the raising and lowering of the dogs on the dog carriages of the indexer arrangement are well known and need not be repeated here in detail. The system of the embodiment of the detailed description is designed to operate the dog carriages in unison so that the dogs of both carriages  24  and  26  are coordinated to operate against both sides of a bogey frame in unison. A control unit is associated with the system and each of the hydraulic motors and carriages. 
         [0029]    This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.