Abstract:
A railcar indexer system is disclosed that includes a design that enables extremely high loads to be moved without exceeding present railcar limitations. The railcar handling system of the present invention employs hydraulically-operated indexers that divide the load between consecutive dog carriages that, in turn, operate to apply force to railcar bogey frames or axles on consecutive railcars. This transfers a large amount of force to be applied to a lead railcar and enables a much larger amount of force to be applied to the next railcar and a larger total force to be applied to a string of railcars.

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 train positioning systems that employ a tandem dog carriage arrangement that enables force to be applied to consecutive railcars which greatly increases the total force available for an indexer to move a string of railcars without exceeding the maximum force allowable on any one railcar. Embodiments of the system of the present invention can be used to operate by engaging the bogey frames or axles 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 dedicated 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 generally classified in the industry as “indexers” position railcars using dogs to push against railcar bogey frames or axles. Bogey frame indexers may employ dogs carried by a pair of carriages operating along indexer tracks on built-in guideways located on opposite sides of associated track rails. Indexers are designed so that the carriages and associate dogs 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 opposite sides of the track are caused to engage the bogey frame during the same stroke to thereby provide a balanced force by pushing against both of the spaced sides of the truck bogey frame simultaneously. Axle-type indexers include a single carriage operated between the tracks that employs dogs to engage truck axles rather than bogey frames. 
         [0009]    Using either type system an entire string of connected cars may be advanced with precision and loaded or unloaded, one car at a time. With the indexer system, the operation can be stopped at any point in the operating cycle when the desired position is reached. These systems may typically be operated using hydraulic cylinders to advance and retract dog carriages and to raise and lower the dogs. 
         [0010]    Operation of car handling equipment in each of the modes described above has certain advantages and either may be desirable depending on operational circumstances and conditions. As indicated, a bogey-frame 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 derailing situation which may occur when force is applied to one side only. However, current railcar designs limit the maximum pushing effort that can be applied to a bogey frame. The total applied force is limited to about 120,000 pounds (˜54,420 kg) when the force is applied on both sides of the frame. For an axle system, the maximum allowed is even less. Current railcar designs limit the allowable pushing effort to 75,000 pounds (˜34,000 kg) on an axle. 
         [0011]    These load limitations force the indexers to limit the permissible loads to be moved to a lesser amount than is often desired by system users. Therefore, it would be highly desirable if a system could be developed that would enable higher loads to be moved without exceeding the design tolerances of the railcars. 
       SUMMARY OF THE INVENTION 
       [0012]    By means of the present invention, there is provided a railcar indexer system that includes a design that enables extremely high loads to be moved without exceeding present railcar limitations. The railcar handling system of the present invention employs hydraulically-operated indexers that divide the load between multiple dog carriages that, in turn, operate to apply force to a plurality of railcar bogey frames or axles on consecutive railcars. This basically doubles the amount of force that can be applied to a string of railcars. 
         [0013]    One preferred embodiment employs two dog carriages in tandem with a lead dog carriage designed to engage the last bogey frame or axle of a first or lead railcar and the trailing dog carriage designed to engage the first bogey frame or last axle of the first bogey frame of the second or trailing railcar. The system includes a plurality of consecutive, series-connected hydraulic cylinders. The final cylinder of the plurality of cylinders or trailing carriage cylinder is attached to the trailing dog carriage. An additional, or tandem, cylinder is located between the two dog carriages. The tandem cylinder is used to transfer and apply force to the lead dog carriage during a power stroke. The tandem cylinder is preferably designed to exert one-half of the force of, and is connected in series with, the trailing carriage cylinder. Of course, the tandem cylinder may be sized to deliver any desired percentage of the force of the trailing carriage cylinder. Thus, when the indexer is fully engaged in the preferred embodiment, the maximum allowable force can be exerted against the last bogey frame or axle of the first or lead railcar by the lead dog carriage and double the allowable force can be exerted against the first bogey frame or an axle of the first truck of the second or trailing railcar. This results in a transfer of one-half of the force applied to the tracking railcar to the lead railcar. This, in turn, results in an ability to double the total force exerted with respect to a connected string of cars without exceeding the force allowed on an individual bogey frame or axle. 
         [0014]    The system designed as a bogey frame engaging system includes one tandem carriage arrangement on each side of the track. The system designed to engage the railcar axles is located between the rails so that the dogs engage the center of the axle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    In the drawings: 
           [0016]      FIG. 1A  is a schematic plan or general layout view of a bogey frame engaging indexer in accordance with the invention with parts broken away for convenience; 
           [0017]      FIG. 1B  is a side elevational view of the indexer of  FIG. 1A ; 
           [0018]      FIG. 2A  is a fragmentary side elevational view of railcars engaged by the indexer of  FIG. 2B ; 
           [0019]      FIG. 2B  is a fragmentary schematic side elevational view of the indexer of  FIG. 2C   
           [0020]      FIG. 2C  is a partial schematic plan or general layout view for an axle-engaging indexer in accordance with the invention with parts broken away for clarity; 
           [0021]      FIG. 2D  is an enlarged sectional view through the system of  FIGS. 2A and 2B  showing a raised dog; 
           [0022]      FIGS. 3A-3C  depict a hydraulic schematic for an indexer in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The following detailed description is directed to one or more embodiments of the invention which are presented as examples and are not intended to limit the scope of the invention in any way as variations that are within the scope of the inventive concepts may occur to those skilled in the art. 
         [0024]    Terms such as “left, right, first, second, lead, trailing, up, down, horizontal, vertical” are arbitrary or general terms taken in connection with the figures and should not be construed as absolute terms. 
         [0025]      FIGS. 1A and 1B  show schematic plan layout and side elevational views of a bogey frame engaging indexer in accordance with the invention. The indexer system, generally at  10 , includes two identical units, which may be designated for convenience as a left unit  12  and a right unit  14  mounted in guideways  16  and  18 , respectively, situated on opposite sides of a railroad track having left and right rails  20  and  22 . The system is generally designed to move railcars from right to left with respect to the drawing. Inasmuch as the two units are substantially identical, only one needs to be described in detail here. Thus, right unit  14  will be described. 
         [0026]    Right unit  14  employs two dog carriages in tandem, including first or lead dog carriage  24  and second or trailing dog carriage  26  with a hydraulic cylinder  28  mounted between and separating the dog carriages. The unit is operated by a plurality of consecutively mounted serially connected hydraulic cylinders, some of which are shown at  30  and  32 . It will be appreciated that the combined stroke length of the consecutively mounted cylinders determines the maximum indexer stroke length and the maximum length of a railcar that can be accommodated in a string of railcars. Raised dogs are shown at  40  and  42 . 
         [0027]      FIGS. 2A-2D  illustrate an embodiment of the railcar indexing system of the invention directed to engage the axles of railcars. A partial schematic plan or general layout view is shown generally at  100  in  FIG. 2C  and includes a first or lead dog carriage  102  and second or trailing dog carriage  104 . The carriages are connected by a pair of spaced hydraulic cylinders  106  and  108  and carriage  104  is connected to be moved by a number of serially-connected hydraulic cylinders, several of which are shown in part at  110 ,  112  and  114 . It will be appreciated that any number of cylinders can be used and the total stroke length of the system will depend on the combined extension of the serially-connected cylinders. 
         [0028]    Dog carriage  102  carries a pair of opposed pusher dogs  120  and  122  and dog carriage  104  carries a pair of similar pusher dogs  124  and  126 . The dog carriages operate along a guideway  130  located between track rails  132  and  134 . As best seen in  FIG. 2D , the rails in the area of operation of the system are supported on spaced rail spacers as at  136  and  138 , rather than cross ties, and the rail spacers and guideway are fixed to a concrete footing  140 . A railcar wheel sensor device is shown at  142 . 
         [0029]      FIG. 2A  depicts fragmentary views of consecutive joined railcars  150  and  152 . The last support truck of first or lead railcar  150  is shown at  154  and the first truck of the second or trailing railcar is shown at  156 . Dog  122  is seen engaging axle  158  of truck  154  and dog  126  is seen engaging axle  160  of truck  156 . It will be appreciated that, although the system is described as moving the railcars from right to left in the drawings, it is a reversing system and can use dogs  120  and  124  to move the railcars from left to right, if desired. 
         [0030]      FIGS. 3A-3C  together depict a schematic hydraulic diagram of one suitable hydraulic operating system for an indexer in accordance with the invention, including valves and switching devices used to control and coordinate the operation of one indexing unit. Connectors A, B, C, D, E, F, G and H simply indicate correspondence to like designated lines in an adjacent view. 
         [0031]    The hydraulic system includes a main hydraulic pump  202 , which may be a variable displacement piston pump, such as a 60 GPM pump, driven by a suitable motor  204 , which may be a 75 horsepower, 1800 RPM, 575/3/60 motor connected by a suitable coupling at  206 . The pump input line  208  includes a strainer  210  and shutoff valve  212 . A drain connection is shown at  214  and a fluid reservoir at  216 . High pressure output line  218  includes a filter arrangement with by-pass line  220 , a check valve  222 , and flow selection valves  224  and  225 . A proportional pressure relief valve is shown at  226 . Manifold  1  is depicted by broken line  228 . A three-position system control valve is shown at  230  that connects line  218  with an extend line  232 , a retract line  234 , and includes connections to a return line  314  and drain line  318 . 
         [0032]    As seen in  FIGS. 3A and 3B , the illustrative indexer may be described as moving railcars from right to left in the drawing and is, but as indicated above, a reversing system that can operate in either direction. The carriage-moving aspect of the indexer is characterized by four serially connected cylinder, including static or stationary cylinder  240  and dynamic or moving cylinders  242 ,  244  and  246  and a pair of spaced parallel fifth and sixth tandem cylinders  248  and  249  mounted between and in line with tandem dog carriages  250  and  252 . 
         [0033]    Carriage  250  includes a pair of spaced opposed dogs  254  and  256  operated by cylinders  258  and  260 , respectively. Carriage  252  includes opposed dogs  262  and  264  operated by cylinder  266  and  268 , respectively. Carriage  252  may be designated as the first or lead dog carriage and carriage  250  as the second or trailing dog carriage. Manifold  3 , designated by broken line  270 , further includes extend line  272 , retract line  274  and solenoid valve  276 , which operate tandem cylinder  248 , as will be described. Manifold  4 , associated with first or lead dog carriage  252 , is outline by broken line  280  and supplied by extend and retract lines  282  and  284  and includes solenoid valve  286 . 
         [0034]    Manifold  1  further contains counterbalance valves  290  and  292 , solenoid valves  296 ,  298 ,  300 ,  302 ,  304  and  306 . Valve  308  and lines  310  and  312  are part of a decompression circuit associated with lowering the dogs that allows high pressure hydraulic fluid to be metered back to the reservoir when solenoid  298  is energized. Return lines are shown at  314  and  316 . Line  314  includes a return fluid cooling arrangement  320  and a return fluid filter  322 . 
         [0035]    Additional valves and gauges are shown in Manifold  2 , outlined at  330 . Thus, retract pressure gauge  332  measures the retraction pressure in parallel line at  336 . Extend pressure gauge  342  measures the pressure in connected line  338  at  340 . Gauge  344  measures the front pump pressure in line  346  at  348 . 
         [0036]    Reservoir  216  includes low liquid level and low temperature switches at  360  and  362 , respectively. A heater  364  and sight gauge  366 , along with a reservoir isolator shown at  368 . Limits for the system are normally set so that the hydraulic fluid must be at least 20° F. at startup and the operating range should be about 107° F. to 140° F. 
         [0037]    In operation, it will be appreciated that, in the case of a bogey frame engaging system, there will be a unit on each side of the track and they will coordinate. Both units may be operated by a common hydraulic system, however. In an axle-engaging system, one system will be located between the rails of the track. 
         [0038]    The operation begins with a string of connected railcars being advanced into a position close to an unloading pit, or the like, to be acted upon by the indexer. With the pump operating, oil in extend line  232  is supplied to the blind end of cylinder  240  and the four serially connected cylinders  240 - 246  begin to extend. As the cylinders extend, oil is expelled from the rod end of cylinder  246  into line  274 . The dogs are biased, as by strong springs in a down position and considerable fluid pressure is required to raise the dogs. The pressure in the lines is insufficient to raise the dogs  254  and  256 , although the rod ends of cylinders  258  and  260  are connected. Oil displaced from cylinder  246  bypasses counterbalance valve  290  through an energized valve  302 . The cylinders  240 - 246  continue to extend and move dog carriages  250  and  252  to the left until a wheel is sensed by a wheel sensor on carriage  250  that detects the presence of a railcar truck. At this point, solenoid  302  de-energizes forcing the oil to flow from the rod end of cylinders  240 - 246  through counterbalance valve  290  putting full pressure on cylinders  250  and  260  which causes dogs  254  and  256  to rise. When the sensors indicate dogs  254  and  256  have risen, solenoid  276  energizes allowing flow into the blind end of cylinders  248  and  249  causing them to extend. The cylinders  240 - 249  continue to extend and move dog carriages  250  and  252  to the left until a wheel is sensed by a wheel sensor on carriage  252  that detects the presence of a railcar truck. At this point, solenoid  286  is caused to switch and fluid in line  284  causes the dogs  262  and  264  to rise. 
         [0039]    In the above manner, consecutive bogey frames of two railcars are addressed by the dogs of consecutive carriages. At the same time, an identical unit is operated on the opposite side of the track so that both sides of both bogey frames are encountered and subjected to equal force. The total force enabled is the sum of the force exerted by the two units. With an axle-engaging unit, the total force is that of a single, central unit. 
         [0040]    The internal cross-sectional area of each of the tandem cylinders  248  and  249  is preferably sized to be one-quarter of that of cylinders  240 - 246  so that it provides one-quarter of the force of the cylinders  240 - 246 . In this manner, together cylinder  248  and  249  produce one-half the force of cylinders  240 - 246 . Thus, if the dogs of carriage  252  are enabled to push against the bogey frame of the lead railcar using the maximum allowable force, the allowable force exerted by the dogs of carriage  250  can be twice that amount. The combination enables the system, in effect, to exert the maximum allowable force against two consecutive railcars, thereby providing double the total force available to move a string of connected railcars. 
         [0041]    Likewise, the axle-engaging indexer will split the load between the last axle of the first or lead car and the second axle of the first truck of the second or trailing railcar. 
         [0042]    It will also be appreciated that longer systems may be provided that address three cars, or even more, if desired, using additional carriages and cylinders to push against additional bogey frames or axles. 
         [0043]    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.