Patent Publication Number: US-2013253739-A1

Title: System and method for dynamically determining a force applied through a rail vehicle axle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/419,888 filed Mar. 14, 2012, which is a divisional of U.S. patent application Ser. No. 11/871,753 filed Oct. 12, 2007, the disclosure of which is incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates to rail vehicles, and, more particularly, to a system for dynamically determining a force applied through a plurality of locomotive axles in a locomotive. 
     A diesel-electric locomotive typically includes a diesel internal combustion engine coupled to drive a rotor of at least one traction alternator to produce alternating current (AC) electrical power. The traction alternator may be electrically coupled to power one or more electric traction motors mechanically coupled to apply torque to one or more axles of the locomotive. The traction motors may include AC motors operable with AC power, or direct current motors operable with direct current (DC) power. For DC motor operation, a rectifier may be provided to convert the AC power produced by the traction alternator to DC power for powering the DC motors. 
     AC-motor-equipped locomotives typically exhibit better performance and have higher reliability and lower maintenance than DC motor equipped locomotives. In addition, more responsive individual motor control may be provided in AC-motor-equipped locomotives, for example, via use of inverter-based motor control. However, DC-motor-equipped locomotives are relatively less expensive than comparable AC-motor-equipped locomotives. Thus, for certain hauling applications, such as when hauling relatively light freight and/or relatively short trains, it may be more cost efficient to use a DC-motor-equipped locomotive instead of an AC-motor-equipped locomotive. 
     For relatively heavy hauling applications, diesel-electric locomotives are typically configured to have two trucks including three axles per truck, where the three axles include one or more powered axles and one or more nonpowered axles. Each powered axle of the truck is typically coupled, via a gear set, to a respective motor mounted in the truck near the axle. Each axle is mounted to the truck via a suspension assembly that typically includes one or more springs for transferring a respective portion of a locomotive weight (including a locomotive body weight and a locomotive truck weight) to the axle while allowing some degree of movement of the axle relative to the truck. 
     A locomotive body weight is typically configured to be about equally distributed between the two trucks. The locomotive weight is usually further configured to be symmetrically distributed among the axles of the trucks. For example, a conventional locomotive weighing 420,000 pounds is typically configured to equally distribute weight to the six axles of the locomotive, so that each axle supports a force of 420,000/6 pounds per axle, or 70,000 pounds per axle. 
     Locomotives are typically manufactured to distribute weight symmetrically to the trucks and then to the axles of the trucks so that relatively equal portions of the weight of the locomotive are distributed to the axles. Typically, the weight of the locomotive and the adhesion capability of the locomotive determine a tractive effort capability rating of the locomotive. Accordingly, the weight applied to each of the powered axles times the amount of friction or adhesion that can be developed to the powered axle determines a tractive effort capability of the corresponding powered axle. Consequently, the heavier a locomotive, the more tractive effort that it can generate. Additional weight, or ballast, may be added to a locomotive to bring it up to a desired overall weight for achieving a desired tractive effort capability. For example, due to manufacturing tolerances that may result in varying overall weights among locomotives built to a same specification, locomotives are commonly configured to be slightly lighter than required to meet a desired tractive effort capability, and then ballast is added to reach a desired overall weight capable of meeting the desired tractive effort rating. In conventional locomotive systems, the weight distribution among the powered axles and nonpowered axles is statically adjusted prior to shipment, and is not capable of being dynamically adjusted once the locomotive trip has begun. 
     Accordingly, a locomotive system is needed that may be used to dynamically determine a force applied through a plurality of locomotive axles in a locomotive, so to dynamically adjust a weight distribution among the locomotive axles. 
     BRIEF DESCRIPTION OF THE INVENTION 
     One embodiment of the present invention provides a system for dynamically determining a force applied through a plurality of axles in a rail vehicle configured to travel along a rail track in a travel direction. The rail vehicle includes a plurality of wheels received by the plurality of axles. The system includes a controller configured to determine a respective dynamic weight shift of the plurality of wheels on the rail track based upon a dynamic factor of the rail vehicle as the rail vehicle travels along the rail track. 
     Another embodiment of the present invention provides a system for dynamically determining a force applied through a plurality of axles in a rail vehicle configured to travel along a rail track in a travel direction. The system includes a controller configured to receive a rail track condition, a rail vehicle operating condition, an operator input, and/or a geographical input of a location along the rail track. The controller is configured to determine a respective dynamic weight command of the plurality of axles on the rail track to dynamically shift a respective weight of the plurality of axles on the rail track based upon the rail track condition, a rail vehicle operating condition, an operator input, and/or a geographical input of a location along the rail track. 
     Another embodiment of the present invention provides a method for dynamically determining a force applied through a plurality of axles in a rail vehicle configured to travel along a rail track in a travel direction. The rail vehicle includes a plurality of wheels received by the plurality of axles. The method includes configuring a controller to receive at least one characteristic of the rail vehicle. Additionally, the method includes determining a static weight of the plurality of axles on the rail track when the rail vehicle is stationary. The method further includes configuring the controller to determine a respective dynamic weight of the plurality of wheels on the rail track based upon the static weight of the plurality of wheels and a dynamic factor of the rail vehicle as the rail vehicle travels along the rail track. 
     Another embodiment of the present invention provides computer readable media containing program instructions for dynamically determining a force applied through a plurality of axles in a rail vehicle configured to travel along a rail track in a travel direction. The rail vehicle includes a plurality of wheels received by the plurality of axles. The computer readable media includes a computer program code for determining a static weight of the plurality of axles on the rail track when the rail vehicle is stationary. The computer readable media further includes a computer program code for determining a respective dynamic weight of the plurality of wheels on the rail track based upon the static weight of the plurality of axles and a dynamic factor of the rail vehicle as the rail vehicle travels along the rail track. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. These drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope. 
         FIG. 1  is a side view of an exemplary embodiment of a conventional locomotive with a pair of trucks in a reverse alignment; 
         FIG. 2  is a side view of an exemplary embodiment of a system for dynamically affecting a normal force applied through a locomotive axle of a locomotive with a pair of trucks in a common alignment; 
         FIG. 3  is a partial side view of an exemplary embodiment of a conventional locomotive truck including a powered axle and a nonpowered axle received by the truck; 
         FIG. 4  is a partial side view of an exemplary embodiment of a system for coupling at least two locomotive axles on a locomotive; 
         FIG. 5  is a side view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 6  is a partial side view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle illustrated in  FIG. 5 ; 
         FIG. 7  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 8  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 9  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 10  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 11  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 12  is a schematic view of an exemplary embodiment of a system for dynamically affecting a force applied through a locomotive axle of a locomotive configured to travel along a rail track; 
         FIG. 13  is a schematic view of an exemplary embodiment of a system for determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track; 
         FIG. 14  is a schematic view of an exemplary embodiment of a system for determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track; 
         FIG. 15  is a schematic view of an exemplary embodiment of a system for determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track; and 
         FIG. 16  is an exemplary embodiment of a method for determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the embodiments consistent with the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings and refer to the same or like parts. 
       FIG. 1  illustrates an exemplary embodiment of a system  10  for dynamically affecting a normal force  12  applied through one or more of a plurality of locomotive axles  30 , 32 , 34 , 36 , 38 , 40 . Although  FIG. 1  illustrates a locomotive  18 , the embodiment of the system  10  of the present invention, and all embodiments of the present invention discussed below, may be utilized with any rail vehicle, including a locomotive, for example. The locomotive  18  illustrated in  FIG. 1  is configured to travel along a rail track (not shown), and includes a plurality of locomotive wheels  20  which are each received by a respective axle  30 , 32 , 34 , 36 , 38 , 40 . The plurality of wheels  20  received by each axle  30 , 32 , 34 , 36 , 38 , 40  are configured to move along a respective rail of the rail track in a travel direction  24 . 
     As illustrated in the exemplary embodiment of  FIG. 1 , the locomotive  18  includes a pair of rotatable trucks  26 , 28  which are configured to receive a respective plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ). The pair of rotatable trucks  26 , 28  are configured to be rotated from an opposite alignment  43  ( FIG. 1 ) to a common alignment  42  ( FIG. 2 ) with respect to the travel direction  24 , such that the common alignment  42  of the trucks  26 , 28  is configured to enhance the traction performance of the locomotive  18  as the locomotive travels along the rail track. Each rotatable truck  26 , 28  includes a pair of spaced powered axles ( 30 , 34 )( 36 , 40 ) and a nonpowered axle ( 32 )( 38 ) positioned between the pair of spaced powered axles. The powered axles ( 30 , 34 )( 36 , 40 ) are respectively coupled to a traction motor  44  and a gear  46 . The combination of the respective powered axle ( 30 , 34 )( 36 , 40 ) and respective traction motor  44  may be referred to as the “combo,” and a stationary (i.e. non-rotating) component of the “combo” is coupled to the respective truck  26 , 28  using a reaction member  133 , as illustrated in  FIGS. 1-4 . The reaction member  133  couples the stationary component of the “combo” to the respective truck  26 , 28  frame to exert a vertical force which displaces the “combo” relative to the truck  26 , 28  frame in the vertical direction. The direction of the vertical force is upward or downward, depending on the direction  24  of the tractive effort. In the exemplary embodiment of the opposite alignment  43  illustrated in  FIG. 1 , the respective gear  46  of a pair of powered axles  30 , 34  for one of the trucks  26  are positioned on an opposite side of the powered axles  30 , 34 , relative to the direction of travel  24 , thereby causing an upward force on the powered axles  30 , 34  and reducing the tractive effort of the locomotive  18 . In stark contrast, the exemplary embodiment of the common alignment  42  illustrated in  FIG. 2  illustrates the respective gear  46  of all powered axles  30 , 34 , 36 , 40  for all trucks  26 , 28  positioned on the same relative side  48  of the powered axles  30 , 34 , 36 , 40  as the direction of travel  24 , thereby causing a downward force  12  on the powered axles  30 , 34 , 36 , 40 , and increasing the tractive effort of the locomotive  18 . 
     Upon rotating the trucks  26 , 28  to the common alignment  42 , the weight imparted by the powered axles ( 30 , 34 )( 36 , 40 ) on the rail track increases, while the weight imparted by the nonpowered axles ( 32 )( 38 ) on the rail track decreases, as compared to the respective values in the opposite alignment  43  arrangement. Although  FIGS. 1-2  illustrate a pair of spaced apart powered axles and a nonpowered axle positioned therebetween within each truck, the trucks  26 , 28  may include any number of powered axles and at least one nonpowered axle, within any positional arrangement. The trucks  26 , 28  may be rotated by removing the locomotive  18  from the rail track and rotating the trucks  26 , 28  about a traction pin (not shown), for example, before repositioning the locomotive  18  on the rail track with the trucks  26 , 28  in the new relative alignment. 
     Although the system  10  increases the traction performance of the locomotive  18  by rotating the trucks  26 , 28  to a common alignment  42 , the system  10  may further include an optional device  27 , 29  ( FIG. 2 ) coupled to the respective axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) of the trucks  26 , 28 , to provide additional traction performance. Although  FIG. 2  illustrates a single device  27 , 29  respectively coupled to each truck  26 , 28 , a single device may be individually coupled to each axle, as discussed in the embodiments below. The optional device  27 , 29  is discussed generally herein, and more specific examples of the device  27 , 29  are discussed in detail in other later embodiments of the present invention. However, the system  10  may increase the traction performance of the locomotive  18  with the rotatable trucks  26 , 28 , and without the optional device  27 , 29 . 
     As illustrated in the exemplary embodiment of  FIG. 2 , a respective device  27 , 29  may be coupled to the trucks  26 , 28  of the locomotive  18 , where each device is configured to dynamically affect the normal force  12  applied through one or more of the axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) in a normal direction to the rail track surface in contact with the wheels  20 . In dynamically affecting the normal force  12 , one or more characteristics of the normal force  12  is selected to affect the traction performance of the locomotive  18  as the locomotive  18  travels along the rail track. For example, such characteristics of the normal force  12  may include the magnitude and/or direction of the normal force  12 . 
     In an exemplary embodiment of the system  10 , the respective device  27 , 29  is configured to increase the aggregate adhesion between the plurality of locomotive wheels  20  and the rail track, by selecting a characteristic of the normal force and dynamically affecting that characteristic. For example, a first axle  30  of the axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) is coupled to a respective pair of wheels  20  in a slipping condition on the rail track. Additionally, a second axle  34  is coupled to a respective pair of wheels  20  in a non-slipping condition on the rail track. The respective device  27  is configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through the first axle  30  to control a creep condition of the respective pair of wheels  20 , and reduce the slipping condition of the pair of wheels  20 , for example. Additionally, the respective device  27  is configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through the second axle  32  to control a creep condition of the respective pair of wheels  20  and maintain the non-slipping condition of the pair of wheels  20 , for example. 
     In a further exemplary embodiment, the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) may include a performance limited axle, and the respective device  27  may be configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through the performance limited axle to reduce a level of tractive effort passed through the performance limited axle. Examples of such a performance limited axle include: an axle having incurred a limitation in tractive effort attributed to a failure of a mechanical and/or electrical component of the locomotive  18 , a thermally affected axle based on a temperature of the traction motor, a mechanical drive train and electric drive of the thermally affected axle exceeding a predetermined threshold, and a reduced capability axle providing limited traction effort efficiency. 
     In an additional exemplary embodiment of the system  10 , the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) include a friction brake axle, where during the application of a locomotive brake such as an emergency air brake, an independent brake or a train brake, the respective device  27 , 29  is configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through the friction brake axle. The dynamic affect of the normal force  12  is based on an open loop or closed loop format, where the closed loop format involves a sensor coupled to the device  27 , 29  to detect a creep factor of the friction brake axle. The device  27 , 29  is configured to dynamically affect the normal force  12  based upon the creep factor received from the sensor. However, the open loop format involves the respective device  27 , 29  dynamically affecting the magnitude and/or direction of the normal force  12 , until a particular parameter is achieved, such as a minimum increase in the tractive performance of the locomotive, for example. 
     In an additional exemplary embodiment of the system  10 , the plurality of wheels  20  may include a flatspot wheel with a flat spot along a circumference of the wheel  20 . The respective device  27 , 29  is configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through an axle  30  which has received the flatspot wheel  20  to impart an upward lift force on the flatspot wheel  20  to limit damage to the flatspot wheel, the rail track, and/or the locomotive  18 . If the respective device  27 , 29  does not dynamically affect the magnitude and/or direction of the normal force  12  through the axle  30  and impart the upward lift force on the flatspot wheel  20 , the flat spot along the flatspot wheel  20  would increase, and possibly lead to damage of the locomotive  18 . In an additional exemplary embodiment of the system  10 , the plurality of wheels  20  may include a locked wheel  20 , received by a respective locked axle  30 . In the exemplary embodiment, the respective device  27 , 29  is configured to dynamically affect the magnitude and/or direction of the normal force  12  applied through the respective locked axle  30  to impart an upward lift force on the locked wheel  20  to reduce a likelihood of locomotive derailment. 
     As discussed above, the system  10  is provided to affect a traction performance characteristic of the locomotive  18 , and such traction performance characteristics may be based upon an operating characteristic of the locomotive  18 . For example, the dynamic affect of the normal force  12  applied through the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) is configured to affect the traction performance of the locomotive  18  when the locomotive  18  is traveling over the rail track at a low speed lower than a speed threshold. Additionally, the traction performance affected by the system  10  may include a creep factor of the plurality of wheels  20  and a tractive effort of the plurality of wheels  20 , for example. In another example, the dynamic affect of the normal force  12  applied the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) is configured to affect a wheel wear of the plurality of wheels  20 , a ride quality of the locomotive  18 , or a creep factor of the plurality of wheels  20  when the locomotive  18  is traveling over the rail track at a high speed greater than a speed threshold. The speed threshold may be any arbitrary speed, such as 12 miles per hour, for example. In yet another example, the dynamic affect of the normal force  12  applied through the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) is configured to dynamically control a respective weight of a pair of wheels  20  across an axle  30  which receives the pair of wheels  20 , and/or to dynamically control a respective weight distribution between two axles  30 , 32 , to affect a curve performance characteristic of the locomotive  18  when the locomotive  18  travels over a curve in the rail track. Although the exemplary embodiment refers to dynamically controlling the weight of the pair of wheels  20  across the axle  30 , the system may dynamically control the weight of a pair of wheels across multiple axles. Additionally, although the exemplary embodiment refers to dynamically controlling a weight distribution between two axles  30 , 32 , the system may be employed to dynamically control weight distribution between more than two axles. 
     In an additional exemplary embodiment of the system  10 , the respective device  27 , 29  may dynamically affect a lateral force perpendicular to the normal force  12 , where the lateral force is applied through a locomotive axle  30  in the locomotive  18  to enhance a curve performance characteristic of the locomotive  18  when the locomotive travels along a curve in the rail track. 
     In an additional exemplary embodiment of the system  10 , upon a weight of the locomotive  18  having decreased by a weight of consumed locomotive fuel, the respective device  27 , 29  is configured to dynamically affect the respective normal force  12  passing through the powered axle  30  and the nonpowered axle  32  to increase a weight of the powered axle  30  to the weight of the powered axle  30  prior to the consumption of the locomotive fuel, and further to decrease a weight of the nonpowered axle  32  to a weight lower than a weight of the nonpowered axle  32  prior to the consumption of the locomotive fuel. In one exemplary embodiment, the weight of consumed locomotive fuel is determined by an algorithm performed by a locomotive controller, or a direct fuel level measurement within the fuel tank. When dynamically affecting the normal force  12  to increase the weight of the powered axle  30 , the increase in the weight of the powered axle  30  is configured not to exceed a respective weight threshold for the powered axle  30 . 
     In an additional exemplary embodiment of the system  10 , the device  27 , 29  is configured to dynamically affect the force  12  applied through the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) to reduce an amount of ballast on the locomotive  18 . The dynamic affect of the normal force  12  through the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) is utilized to provide a weight balance of the locomotive  18  across opposing ends, where the weight balance is configured to reduce a need to provide ballast on the locomotive. 
     In an additional exemplary embodiment of the system  10 , the plurality of axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) include powered axles ( 30 , 34 )( 36 , 40 ) and a nonpowered axle ( 32 )( 38 ), and the dynamic affect of the normal force  12  through the axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) involves a weight shift to the powered axles ( 30 , 34 )( 36 , 40 ) for a limited time period to achieve one or more traction performance requirements of the locomotive  18 . A maximum weight shift to the powered axles ( 30 , 34 )( 36 , 40 ) from the nonpowered axle ( 32 , 38 ) is performed within a minimum time period to minimize a structural impact on a locomotive  18  and rail track infrastructure. In an exemplary embodiment, such a maximum weight shift is 20,000 lbs, for example. In an additional exemplary embodiment, the plurality of wheels  20  have a respective plurality of diameters, where the respective device  27 , 29  is configured to dynamically affect the normal force  12  passed through the axles ( 30 , 32 , 34 )( 36 , 38 , 40 ) to normalize a wheel wear characteristic of the plurality of wheels  20  attributed to a disparity in the respective plurality of diameters. 
       FIG. 3  illustrates a conventional truck  126  of a locomotive  116 , in which a powered axle  112  and a nonpowered axle  114  are not directly coupled to one another.  FIG. 4  illustrates an exemplary embodiment of a system  110  for coupling the powered axle  112  to the nonpowered axle  114  on a locomotive  116 . The locomotive  116  includes a plurality of locomotive wheels  118  and a rail track (not shown), where the plurality of locomotive wheels  118  are received by a respective axle  112 , 114 . 
     The system  110  includes a coupling device  124 , which is configured to couple the powered axles  112 , 115  to the nonpowered axle  114  to dynamically affect forces  128 , 129  applied through one of the powered axles  112 , 115  and nonpowered axle  114 . One or more characteristics of the forces  128 , 129  applied through the powered axles  112 , 115  and nonpowered axle  114  are selected to affect the traction performance of the locomotive  116  as the locomotive travels along the rail track. In an exemplary embodiment, the one or more characteristics of the forces  128 , 129  are selected to optimize the traction performance of the locomotive  116  as the locomotive travels along the rail track. 
     In the exemplary embodiment of the system  110  illustrated in  FIG. 4 , the dynamic affect of the forces  128 , 129  applied through one or more of the powered axles  112 , 115  and nonpowered axle  114  is configured to affect a level of tractive effort passed through the axles  112 , 115 ,  114 . In an exemplary embodiment, a characteristic of the forces  128 , 129  is the magnitude and/or direction of the forces, for example. 
     As illustrated in the exemplary embodiment of  FIG. 4 , the coupling device  124  is a mechanical coupling device configured to mechanically couple the powered axles  112 , 115  and the nonpowered axle  114 . Although  FIG. 4  illustrates the coupling device  124  coupling a pair of powered axles  112 , 115  to a nonpowered axle  114 , the coupling device may be utilized to coupled one powered axle or more than two powered axles to one or more nonpowered axles, for example. The mechanical coupling device  124  is coupled to a respective traction motor  130  of the powered axle  112 . As illustrated in  FIG. 4 , the coupling device  124  is utilized to couple a pair of powered axles  112 ,  115  to the nonpowered axle  114 , and the mechanical coupling device  124  may be a rigid member or a flexible member, and one or more compliant members  113  couples the mechanical coupling device  124  to the nonpowered axle  114 . 
     In the illustrated exemplary embodiment of  FIG. 4 , the pair of powered axles  112 , 115  includes a respective traction motor  130  within a motor frame  131  and a respective gear  132 . Additionally, the pair of powered axles  112 , 115  is rotated by the respective gear  132 , which is driven by the respective traction motor  130 . In the exemplary embodiment of the system  110 , during the rotation of the pair of powered axles  112 , 115  by the respective gear  132 , a force  129  is imparted on the pair of powered axles  112 , 115 , a stationary component of the traction motor, and a rotating component of the traction motor through a bearing. Once the force  129  is imparted on the pair of powered axles  112 , 115  and the stationary component of the traction motor, the mechanical coupling device  124  is coupled to the nonpowered axle  114  through a journal bearing housing  136 . The mechanical coupling device  124  is configured to impart a secondary force  128  on the nonpowered axle  114  through the journal bearing housing  136  to increase the level of tractive effort passed through the pair of powered axles  112 , 115  and the non-powered axle  114 . 
     As discussed above and as illustrated in the exemplary embodiment of  FIG. 2 , the locomotive  116  includes a pair of trucks  26 , 28 , and a respective pair of powered axles  112 , 115  and a nonpowered axle  114  received by a respective truck. A fixed collective force is applied through the respective pair of powered axles  112 , 115  and the nonpowered axle  114  for each respective truck. A variable powered force is applied through the respective pair of powered axles  112 , 115  and a variable nonpowered force is applied through the nonpowered axle  114 , where the sum of the variable powered and nonpowered forces is the fixed collective force. For example, the fixed collective force through a pair of powered axles and a nonpowered axle of a truck may be 210,000 lbs, but the variable powered force applied through the pair of powered axles may vary between 120,000 lbs and 160,000 lbs, while the variable nonpowered force applied through the nonpowered axle may respectively vary between 90,000 lbs and 50,000 lbs, for example. As discussed above, and in further detail below, the coupling device  124  is provided to maximize the variable powered force through the pair of powered axles  112 , 115 , while minimizing the variable nonpowered force through the nonpowered axle  114 . As discussed above, although the illustrated truck in  FIG. 4  includes a respective pair of powered axles  112 , 115  and a nonpowered axle  114 , the truck may include one or more than two powered axles and may include more than one nonpowered axle, for example. The mechanical coupling device  124  is configured to affect the magnitude and/or direction of the variable powered force and the variable nonpowered force applied through the respective pair of powered axles  112 , 115  and the nonpowered axle  114 . 
     As further illustrated in the exemplary embodiment of  FIG. 4 , the mechanical coupling device  124  includes a slot  140  coupled to the stationary component of the traction motor  130 . The slot  140  is configured to receive a respective member  137  coupled to a respective motor frame  131  of the pair of powered axles  112 , 115 . The slot  140  and respective member  137  are configured to provide a one-way coupling such that the mechanical coupling device  124  imparts the secondary force  128  on the nonpowered axle  114  when the force  129  is imparted on the pair of powered axles  112 , 115 , and the mechanical coupling device  124  is decoupled from the nonpowered axle  114  when the force  129  is imparted on the pair of powered axles  112 , 115  in an upward direction away from the rail track to increase a level of tractive effort passed through the pair of powered axles  112 , 115 . The particular slot  140  and respective member  137  are dimensioned and positioned such that the one-way coupling is provided based upon the direction of the force  129  imparted on the pair of the powered axles  112 , 115 , and thus whether the force  129  increases or decreases the tractive effort passed through the pair of powered axles  112 , 115 . 
     As discussed in further detail in the embodiments below, instead of a rigid member, the coupling device  124  may take the form of a plurality of hydraulic actuators respectively coupled to the plurality of axles  112 , 114 , 115 , where a compressed fluid within a first hydraulic actuator coupled to a first axle  112  is selectively supplied to a second hydraulic actuator coupled to a second axle  114  of the plurality of axles. In the exemplary embodiment, the compressed fluid within the second hydraulic actuator is configured to impart the secondary force  128  on the second axle  114 . One of more characteristics of the secondary force  128  may be affected, including the magnitude and/or direction of the force  128 , to increase a level of tractive effort passed through the second axle  114 . 
       FIG. 10  illustrates an exemplary embodiment of a system  310  for dynamically affecting a force applied through a locomotive axle  314  of a locomotive  318  configured to travel along a rail track. The locomotive  318  includes a plurality of locomotive axles and a plurality of locomotive wheels received by the respective plurality of axles. The system  310  includes a device configured to selectively impart a force through a locomotive axle  314  to control a respective weight of the locomotive axle  314  on the rail track for affecting a traction performance of the locomotive  318  traveling along the rail track. Although  FIG. 10  illustrates a system  310  to selectively impart a force through one locomotive axle  314 , the system may be configured to selectively impart a force through more than one locomotive axle. 
     In the illustrated exemplary embodiment of  FIG. 10 , the system  310  includes the device to selectively impart a force through the locomotive axle  314 , such as a hydraulic actuator  326  coupled to the respective locomotive axle  314 . Although  FIG. 10  illustrates one hydraulic actuator  326  coupled to a locomotive axle  314 , a hydraulic actuator may be coupled to more than one respective locomotive axle, to selectively impart a force through the respective locomotive axle. A variable displacement pump  328  is coupled to the hydraulic actuator  326 , and the variable displacement pump  328  is configured to supply a pressurized hydraulic fluid  330  at a selectively controlled pressure to the hydraulic actuator  326 . The hydraulic actuator  326  is configured to selectively impart the force through the respective locomotive axle  314  based upon the selectively controlled pressure. In the illustrated exemplary embodiment of  FIG. 10 , the hydraulic actuator  326  is directly coupled to the respective locomotive axle  314 . Although  FIG. 10  illustrates one variable displacement pump  328 , more than one variable displacement pump may be utilized. A plurality of control valves  332 , 334 , 336 , 338  are respectively coupled to the variable displacement pump  328  and the hydraulic actuator  326 , and the control valves  332 , 334 , 336 , 338  are selectively activated to control the force imparted through the respective locomotive axle  314 . 
       FIG. 11  illustrates an additional exemplary embodiment of a system  310 ′ for dynamically affecting a force applied through a locomotive axle  314 ′ of a locomotive  318 ′ configured to travel along a rail track. As illustrated in the exemplary embodiment of  FIG. 11 , the system  310 ′ includes a compliant member  340 ′, such as a spring, for example, disposed between the hydraulic actuator  326 ′ and the respective locomotive axle  314 ′ such that the hydraulic actuator  326 ′ is coupled to the respective locomotive axle  314 ′ in a compliant manner. The system  310 ′ further includes a pair of displacement limits (not shown) coupled to the hydraulic actuator  326 ′ to limit the force selectively imparted on the respective locomotive axle  314 ′. As further illustrated in the exemplary embodiment of  FIG. 11 , the system  310 ′ includes a plurality of control valves  332 ′, 334 ′, 336 ′, 338 ′ coupled to the variable displacement pump  328 ′ and the hydraulic actuator  326 ′, where the plurality of control valves  332 ′, 334 ′, 336 ′, 338 ′ are selectively activated to control a position  342 ′ of the hydraulic actuator. Those elements not specifically discussed herein are similar to those equivalent-numbered elements described in the previous embodiments, with prime notation, and require no further discussion herein. 
       FIG. 12  illustrates an additional exemplary embodiment of a system  310 ″ for dynamically affecting a force applied through a locomotive axle  314 ″ of a locomotive  318 ″ configured to travel along a rail track. The system  310 ″ includes a positive displacement pump  344 ″ coupled to the hydraulic actuator  326 ″, where the positive displacement pump  344 ″ is configured to selectively control a position  342 ″ of the hydraulic actuator  326 ″ based upon supplying a pressurized hydraulic fluid  330 ″ at a variable pressure to the hydraulic actuator  326 ″. The hydraulic actuator  326 ″ is configured to selectively impart the force through the respective locomotive axle  314 ″ based upon the selectively controlled position  342 ″ of the hydraulic actuator  326 ″. As with the embodiment of  FIG. 11 , a compliant member  340 ″, such as a spring, for example, is disposed between the hydraulic actuator and the respective axle such that the hydraulic actuator is coupled to the respective axle in a compliant manner. Additionally, a plurality of control valves  332 ″, 334 ″, 336 ″, 338 ″ are coupled to the positive displacement pump  344 ″ and the hydraulic actuator  326 ″, where the control valves  332 ″, 334 ″, 336 ″, 338 ″ are selectively activated to control the position  342 ″ of the hydraulic actuator. A pair of displacement limits (not shown) is coupled to the hydraulic actuator  326 ″ to limit the force selectively imparted on the respective locomotive axle  314 ″. Those elements not specifically discussed herein are similar to those equivalent-numbered elements described in the previous embodiments, with double prime notation, and require no further discussion herein. 
       FIGS. 8-9  illustrate a number of exemplary embodiments of a system  310 ′″ for dynamically affecting a force applied through a locomotive axle  314 ′″ of a locomotive  318 ′″ configured to travel along a rail track. As illustrated in the exemplary embodiment of  FIG. 8 , the system  310 ′″ includes a hydraulic actuator  326 ′″ configured to selectively impart the force through the respective locomotive axle  314 ′″ based upon energy captured from a vibration of a vibrated axle  316 ′″ of the plurality of axles along the rail track. The system  310 ′″ includes a pressurized hydraulic fluid pump  322 ′″ coupled to the vibrated axle  316 ′″ and the hydraulic actuator  326 ″, where the captured vibrational energy is utilized to pressurize the hydraulic fluid within the hydraulic fluid pump  322 ″. 
     The hydraulic actuator  326 ′″ is configured to selectively impart the force through the respective locomotive axle  314 ′″ based upon the pressurized hydraulic fluid delivered from the pump  322 ′″ to the hydraulic actuator  326 ″. The system  310 ′″ further includes a pair of displacement limits (not shown) coupled to the hydraulic actuator  326 ′″ to limit the force selectively imparted on the respective locomotive axle  314 ′″. A compliant member  340 ′″, such as a spring, for example, is disposed between the hydraulic actuator  326 ′″ and the respective locomotive axle  314 ′″ such that the hydraulic actuator  326 ′″ is coupled to the respective locomotive axle  314 ′″ in a compliant manner. Once the hydraulic actuator  326 ′″ selectively imparts the force through the respective locomotive axle  314 ′″, the compliant member  340 ′″ is configured to exert a reactive force on the respective locomotive axle  314 ′″. Although  FIGS. 8-9  illustrate one vibrated axle  316 ′″ from which vibrational energy is obtained, and one locomotive axle  314 ′″ to which the hydraulic actuator  326 ′″ selectively imparts the force, the system  310 ′″ may include more than one vibration axle from which vibrational energy is obtained and/or more than one locomotive axle to which a respective hydraulic actuator selectively imparts a force. The locomotive axles  314 ′″, 316 ′″ may include one or more powered axles, or one or more nonpowered axles. 
     In the exemplary embodiment illustrated in  FIG. 9 , the pressurized hydraulic fluid pump  322 ′″ has an input which delivers pressurized hydraulic fluid to a bottom chamber of the hydraulic actuator  326 ″ which is coupled to a nonpowered axle  314 ′″, thereby imparting an upward force on the nonpowered axle  314 ′″ in a normal direction to the rail track. In the exemplary embodiment illustrated in  FIG. 8 , the pressurized hydraulic fluid pump  322 ″ has an input which delivers pressurized hydraulic fluid to a top chamber of the hydraulic actuator  326 ″ which is coupled to a powered axle  314 ″, thereby imparting a downward force on the powered axle  314 ″ in a normal direction to the rail track. As further illustrated in the exemplary embodiments of  FIGS. 8-9 , a control valve  346 ′″ is coupled to the hydraulic actuator  326 ′″ to selectively control a pressure difference across the hydraulic actuator  326 ′″. The control valve  346 ′″ may be activated to rapidly remove a weight shift imparted on a respective locomotive axle  314 ′″ based upon the selective imparting of the force on the respective locomotive axle  314 ′″. In addition to the control valve  346 ′″, the exemplary embodiments of  FIGS. 8-9  include a high restriction valve  348 ′″ coupled to the hydraulic actuator  326 ′″ to selectively decrease a pressure difference across the hydraulic actuator  326 ′″. The high restriction valve  348 ′″ is selectively activated to slowly remove a weight shift imparted on a respective locomotive axle  314 ′″ based upon the selective imparting of the force on the respective locomotive axle  314 ′″. Those elements not specifically discussed herein are similar to those equivalent-numbered elements described in the previous embodiments, with triple prime notation, and require no further discussion herein. 
     Although  FIGS. 8-12  illustrate a hydraulic actuator  326 ′″ being utilized as a device to selectively impart a force through a locomotive axle  314 ′″ to control a respective weight of the locomotive axle  314 ′″ on the rail track  320 ′″, a pneumatic actuator  350 ″, as illustrated in  FIGS. 5-7 , may be similarly utilized in place of the hydraulic actuator and similarly coupled to the locomotive axle  314 ′. In an exemplary embodiment of a system  310 ′ illustrated in  FIG. 7 , a controlled pressure regulator  352 ′ is coupled to the pneumatic actuator  350 ′, where the controlled pressure regulator  352 ′ is configured to selectively control a position  354 ′ of the pneumatic actuator  350 ′ based upon supplying pressurized air at a near constant pressure to the pneumatic actuator  350 ′. The pneumatic actuator  350 ′ is configured to selectively impart the force through the respective locomotive axle  314 ′ based upon the selectively controlled position  354 ′ of the pneumatic actuator. The system  310 ′ further includes a pair of control valves  356 ′,  358 ″″ coupled to the controlled pressure regulator  352 ″″ and the pneumatic actuator  350 ″, where the control valves  356 ″,  358 ″″ are selectively activated to control the position  354 ″″ of the pneumatic actuator  350 ′. Although  FIG. 7  illustrates a pair of control valves, less than two or more than two control valves may be utilized. A pair of displacement limits  360 ″,  362 ″″ is coupled to a locomotive truck frame  364 ″, where the respective locomotive axle  314 ′ is received by the locomotive truck frame  364 ″, and the pair of displacement limits  360 ′, 362 ′ are configured to limit the position  354 ′ of the respective locomotive axle  314 ′ based upon the controlled position  354 ″″ of the pneumatic actuator  350 ″″. Additionally, a pair of relief valves  366 ″,  368 ′ are coupled to the pneumatic actuator  350 ′, and are configured to rapidly remove a weight shift imparted on a respective locomotive axle  314 ′ based upon the selectively controlled position  354 ″″ of the pneumatic actuator  350 ″″. Those elements not specifically discussed herein are similar to those equivalent-numbered elements described in the previous embodiments, with quadruple prime notation, and require no further discussion herein. 
     In addition to the embodiments discussed above, the device configured to selectively impart a force through a locomotive axle to control a respective weight of the locomotive axle on the rail track may be a mechanical actuator, an electro-mechanical actuator, a motor driven actuator, a manual driven actuator and a mechanical linkage actuator, coupled to a respective locomotive axle. 
     The above-discussed embodiments describe exemplary embodiments of systems including a device for dynamically affecting a force applied through a locomotive axle. The following embodiment of the present invention discusses a control system for determining the extent of force to apply through one or more locomotive axles, so to enhance the tractive performance of the locomotive.  FIGS. 13-15  illustrate a system  500  for dynamically determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track in a travel direction. The system  500  includes a controller  502  configured to receive one or more locomotive characteristics  504  of the locomotive ( FIG. 13 ) to determine a static weight  503  of the plurality of axles on the rail track when the locomotive is stationary. The system  500  further includes a sensor  506  coupled to the controller  502  ( FIG. 13 ), where the sensor  506  is configured to measure a dynamic factor of a locomotive when the locomotive is in motion along the rail track. In one embodiment of the system  500 , a sensor  506  is configured to measure the speed of the locomotive, and may communicate a signal to the controller  502  upon measuring a speed less than a low speed threshold, for example. In an additional embodiment, a sensor  506  is configured to measure the tractive effort of a respective locomotive axle attributed to a torque applied to a traction motor of the respective locomotive axle. In an additional embodiment, a sensor  506  is configured to measure a level of fuel within a fuel tank of the locomotive, and may communicate a signal to the controller  502  upon measuring a fuel level lower than a fuel level threshold, for example. In an exemplary embodiment, a fuel level algorithm may be utilized to determine the fuel level within the fuel tank, for example. The sensor  506  is configured to communicate the dynamic factor of the locomotive to the controller  502 . The controller  502  is configured to determine a respective dynamic weight  508  of the plurality of wheels on the rail track based upon the static weight  503  of the plurality of wheels and the dynamic factor of the locomotive as the locomotive travels along the rail track. In an exemplary embodiment, the controller  502  may determine a respective dynamic weight shift, instead of a respective dynamic weight of the plurality of wheels on the rail track, based on the dynamic factor of the locomotive, for example. In an exemplary embodiment of the system  500 , the dynamic factor is based upon a tractive effort passed through the plurality of locomotive axles during one of a braking mode or a motoring mode of the locomotive. For example, the dynamic factor may be based upon a brake cylinder pressure  510  applied to the axle during a braking mode, or a torque  512  applied to a traction motor of the axle during a motoring mode, for example. Additionally, the dynamic factor may be based upon a drawbar force  514  exerted on a drawbar coupling the locomotive to an adjacent locomotive or an adjacent train car, for example. 
     As discussed in the previous embodiments, a device may be coupled to a respective locomotive axle and the controller to selectively impart a force through the respective axle, to affect a tractive characteristic of the locomotive. The device may be any one of a hydraulic actuator, a pneumatic actuator, an electro magnetic actuator, a mechanical actuator, a motor driven actuator and a manually operated actuator, for example. In an exemplary embodiment of the system  500 , the sensor  506  may be respectively coupled to the respective locomotive axle, to measure the force imparted by the device through the respective axle, and communicate the measured force to the controller  502 . As further discussed in the previous embodiments of the present invention, such devices are configured to selectively impart a force through the respective axle in a direction away from the rail or toward the rail. The force may be based upon one or more dynamic characteristics of the hydraulic actuator or the pneumatic actuator, for example. In an exemplary embodiment of the system  500 , the sensor  506  is coupled to the hydraulic actuator or the pneumatic actuator to measure the one or more dynamic characteristics of the hydraulic actuator or pneumatic actuator, where the dynamic characteristic may be the position or an applied pressure of the hydraulic actuator or the pneumatic actuator, for example. 
     Additionally, in the exemplary embodiment of  FIG. 13 , the system  500  includes a respective weight sensor  516  coupled to the plurality of axles and the controller  502 , where the respective weight sensor  516  is configured to measure a respective static weight of the plurality of wheels on the rail track when the locomotive is stationary. Upon measuring the static weight of the plurality of wheels on the rail track, the respective weight sensor  516  is configured to communicate the respective static weight to the controller  502 . The respective weight sensor  516  may be provided as a backup or alternative calculation of the static weight  503  calculation based upon the locomotive characteristics  504 , as discussed above. An example of the locomotive characteristics  504  which are utilized to determine the static weight  503  of the locomotive are an established static weight of each wheel on the rail, an established static weight of the locomotive, a static weight of fuel within a locomotive fuel tank, a static weight of sand within a locomotive sand applicator, and a respective diameter of the plurality of wheels. 
     As further illustrated in the exemplary embodiment of  FIG. 13 , the system  500  includes a grade sensor  520  coupled to the locomotive and the controller  502 , where the grade sensor  520  is configured to determine one or more grade factors of the locomotive when the locomotive is stationary. The controller  502  is configured to receive the one or more grade factors to determine the static weight  503  of the plurality of wheels on the rail track. 
     In addition to determining the static weight  503  of the plurality of wheels on the rail track, the controller  502  is configured to determine a respective target weight  522  of the plurality of wheels on the rail. As illustrated in the exemplary embodiment of  FIG. 14 , in which the controller  502  involves an axle weight management algorithm which receives as input the dynamic weight  508  of the plurality of wheels on the rail, and a respective weight threshold  509  for the respective plurality of axles, and generates the respective target weight  522  of the plurality of wheels on the rail. Accordingly, the respective target weight  522  of the plurality of wheels on the rail is based upon the respective dynamic weight  508  of the plurality of wheels on the rail, and the respective weight threshold  509  for the respective plurality of axles. The respective dynamic weight  508  of the plurality of the plurality of wheels on the rail track is subsequently modified to the respective target weight  522  of the respective plurality of wheels. The respective target weight  522  for the plurality of wheels on the rail is configured to affect a level of tractive effort passed through the plurality of wheels along the rail. As illustrated in the exemplary embodiments of  FIGS. 14-15 , upon determining the respective target weight  522  for the plurality of wheels on the rail, the controller  502  is configured to compare the respective target weight  522  of the plurality of wheels on the rail with the respective dynamic weight  508  of the plurality of wheels on the rail. As illustrated in the exemplary embodiment of  FIG. 15 , the controller  502  may compare these quantities in a closed loop or an open loop arrangement. Regardless of which method of comparison is used, upon comparing the respective target weight  522  and the respective dynamic weight  508 , the controller  502  is configured to determine a respective command  524  to a hydraulic actuator or pneumatic actuator respectively coupled to the respective plurality of axles. Although such devices as a hydraulic actuator and pneumatic actuator are discussed in this exemplary embodiment of the controller  502  for imparting a force through the plurality of locomotive axles, other devices may be utilized which similarly are capable of selectively imparting a force through a respective locomotive axle. 
     Upon determining the respective commands  524 , the controller  502  is configured to communicate the respective commands  524  to the respective hydraulic actuator or pneumatic actuator respectively coupled to the plurality of axles and configured to impart a force through the respective axle in a direction either away from the rail or toward the rail, in response to the respective commands  524 . Once the hydraulic actuator or pneumatic actuator impart the force through the respective locomotive axle, the dynamic weight of the plurality of wheels on the rail is modified to the respective target weight of the plurality of wheels on the rail, and one or more tractive characteristics of the locomotive is enhanced. 
     In an additional exemplary embodiment of the system  500 , a controller  502  is configured to determine a respective dynamic weight command  524  of the plurality of axles on the rail track to dynamically shift a respective weight of the plurality of axles on the rail track based upon a rail track condition, a locomotive operating condition, an operator input, and/or a geographical input of a location along the rail track. In an exemplary embodiment of the system  500 , the locomotive operating condition may be a locomotive speed traveling along the rail track, and such a locomotive speed below a speed threshold may prompt the dynamic weight command  524  of the plurality of axles on the rail tracks to shift a respective weight among the plurality of axles. In an additional exemplary embodiment, a notch level of a throttle may be the locomotive operating condition, and upon a locomotive operator increasing the notch level above a notch threshold (e.g.  8 ), this may prompt the dynamic weight command  524  of the plurality of axles on the rail tracks to shift a respective weight among the plurality of axles. In an additional exemplary embodiment, a level of tractive effort may be utilized as the locomotive operating condition and may prompt the dynamic weight command  524  of the plurality of axles, for example. In an additional exemplary embodiment, a creep factor of the plurality of wheels, such as a slipping wheel condition or a non-slipping wheel condition, for example, may be utilized to prompt the dynamic weight command  524  of the plurality of axles, for example. In an additional exemplary embodiment, a level of fuel within a fuel tank of the locomotive may be utilized as the locomotive operating condition to prompt the dynamic weight command  524  of the plurality of axles, for example. In an additional exemplary embodiment, the geographical input of a location along the rail track may be utilized to either designate a particular geographic region to enable dynamic shifting a respective weight of the plurality of axles, or to designate a particular geographic region to refrain from dynamically shifting a respective weight of the plurality of axles. For example, the controller  502  may include a database with the grade, track condition, presence of a bridge, and track material for a range of geographic regions. In an exemplary embodiment, once the controller  502  receives a position identification signal, the controller  502  may determine the track condition in the particular geographic region of the position identification signal to determine whether the track is capable of withstanding a dynamic shift of a respective weight of the plurality of axles. The position identification signal may be obtained from an external GPS satellite (through a receiver mounted on the locomotive), a wayside signal indicating geographic position, or by an internally monitored position by the controller  502  since the commencement of the trip, for example. The controller  502  may evaluate the grade, track condition, bridge presence, and track material, among other factors, based on the geographic region, in order to determine whether the track is capable of the dynamic shift of the respective weight shift of the plurality of axles, for example. 
       FIG. 16  illustrates an exemplary embodiment of a method  600  for dynamically determining a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track in a travel direction. The method  600  begins (block  601 ) by configuring (block  602 ) a controller  502  to receive one or more characteristics  504  of the locomotive. The method  600  further includes determining (block  604 ) a static weight  503  of the plurality of axles on the rail track when the locomotive is stationary. The method  600  further includes configuring (block  606 ) the controller  502  to determine a respective dynamic weight  508  of the plurality of wheels on the rail track based upon the static weight  503  of the plurality of wheels and the dynamic factor of the locomotive as the locomotive travels along the rail track, before ending at block  608 . 
     Based on the foregoing specification, the above-discussed embodiments of the invention may be implemented using computer programming or engineering techniques including computer software, firmware, hardware or any combination or subset thereof, wherein the technical effect is to dynamically determine a force applied through a plurality of locomotive axles in a locomotive configured to travel along a rail track in a travel direction. Any such resulting program, having computer-readable code means, may be embodied or provided within one or more computer-readable media, thereby making a computer program product, i.e., an article of manufacture, according to the discussed embodiments of the invention. The computer readable media may be, for instance, a fixed (hard) drive, diskette, optical disk, magnetic tape, semiconductor memory such as read-only memory (ROM), etc., or any transmitting/receiving medium such as the Internet or other communication network or link. The article of manufacture containing the computer code may be made and/or used by executing the code directly from one medium, by copying the code from one medium to another medium, or by transmitting the code over a network. 
     One skilled in the art of computer science will easily be able to combine the software created as described with appropriate general purpose or special purpose computer hardware, such as a microprocessor, to create a computer system or computer sub-system of the method embodiment of the invention. An apparatus for making, using or selling embodiments of the invention may be one or more processing systems including, but not limited to, a central processing unit (CPU), memory, storage devices, communication links and devices, servers, I/O devices, or any sub-components of one or more processing systems, including software, firmware, hardware or any combination or subset thereof, which embody those discussed embodiments the invention. 
     While exemplary embodiments of the invention have been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes, omissions and/or additions may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.