A material transport and distribution consist including an offloading car, a generator car, and hopper cars. The offloading car includes a rotatable conveyor that can offload materials forward of and to the sides of the car. The generator car powers a plurality of hopper car conveyors. The hopper cars include a longitudinal conveyor that overlaps with conveyors of forward- and aft-located cars to enable transport of materials between cars and while the cars are negotiating a turn in the tracks. The hopper car hoppers are divided into chutes with respective guillotine-style gates. Each gate includes a resilient panel that flexes to enable closure of the gate without binding on materials exiting therefrom. A control system is provided to manage the gates and conveyors during offloading based on sensed characteristics of the operation thereof. An interlock system is also provided to initiate a cascading shutdown routine when a fault is detected.

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/075,641, filed Nov. 5, 2014 and U.S. Provisional Patent Application Ser. No. 62/158,888, filed May 8, 2015, the disclosures of each of which are hereby incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     Transport and distribution of ballast and other materials along railways is a common task carried out by rail maintenance entities. A variety of transport and distribution systems are available in the art. These typically include a number of hopper cars loaded with ballast material that are transported along the rails to a desired dumping location for unloading. Unloading methods include physically tipping over the entire hopper car, tipping only a hopper portion of the hopper car, opening one or more gates to allow the ballast material to flow out of the hopper, and employing one or more conveyor systems, among others. 
     Conveyor systems may comprise one or a plurality of conveyor belts extending longitudinally along the length of the hopper car and/or between a plurality of hopper cars. The conveyors may lie beneath the hoppers, may be disposed within the hopper, or a combination thereof. In known systems the conveyors must extend or overlap between adjacent hopper cars to enable transport of the ballast materials between cars and/or along the length of the consist for distribution. In single-belt conveyance systems, e.g. one belt extending between multiple cars, the curve causes the belt to bend, flex, or turn between cars thus causing binding or flexing of the belt and prevents operation thereof. 
     Gate systems employed with known conveyance systems typically include clamshell or pivoting closure mechanisms in which one or a pair of doors are pivoted between open and closed positions. Other systems may employ guillotine-style gates that slide across an opening, but such guillotine-style gates are typically employed with relatively light weight materials such as grains and organic materials. A problem with known gate systems is that it may be difficult to fully close the gate while materials are moving therethrough; the materials may become pinched, jammed, or crushed between a leading edge of the door/gate and a sidewall of the chute or hopper from which the materials are exiting. Such guillotine-style gates are typically opened and closed using a screw drive system operated by a hand crank, a pneumatic drill, or the like. 
     Operation of the clam shell gate systems and conveyance systems of ballast hopper cars known in the art is labor intensive, i.e. a plurality of operators are required and each must oversee and operate one or more particular parts of the operation. Known systems also subject the operators to dirty and potentially hazardous conditions. Typically, one operator is positioned on a catwalk disposed along the sides of the hopper cars to open the gates and monitor the flow of material from the hoppers onto the conveyors. The gates are opened and closed using a lever. The operator manually adjusts the degree to which the gates are opened to adjust the amount of material flowing onto the conveyor to prevent the conveyor from overloading. Once a first hopper empties, the operator moves along the catwalk to a second hopper and manually opens the gate to allow material to flow from the second hopper onto the conveyor. A second operator, typically positioned in the cab of the power unit, controls the operation of the conveyor. 
     SUMMARY 
     Embodiments of the invention are defined by the claims below, not this summary. A high-level overview of various aspects of the invention is provided here to introduce a selection of concepts that are further described in the Detailed-Description section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. In brief, this disclosure describes, among other things, a material distribution consist, a hopper gate, material distribution control systems, and methods for their use. 
     The material distribution consist includes a plurality of hopper cars, an offloading car, and a generator car. Each hopper car includes an individual conveyor extending under a plurality of gated hopper compartments. Each hopper compartment may be formed from inwardly and downwardly sloped sidewalls mounted within the hopper to form a chute with a gate disposed at a lower end thereof. A forward most chute includes a bottom surface and gate disposed at an angle that is inclined toward the forward end of the car. 
     The gates are opened and closed to control the flow of material from the hopper compartments onto the conveyor. The amount of material deposited on or flowing onto each conveyor is monitored to control the operation of the gates or the conveyor or both. The gates are configured to facilitate opening and closing of the gates while material is flowing through the opening with which the gate is associated. 
     Each of the gates includes a chute extension coupled to a base frame and a sliding plate that is moveable to close or open an aperture formed by the chute extension. The base frame includes a plurality of support bars extending across the aperture and beyond one side of the gate a distance sufficient to continuously support the sliding plate from the fully open to the fully closed positions. The sliding plate includes a plurality of guides disposed on a bottom surface thereof that are configured to travel along a respective one of the support bars. A resilient panel is provided on the chute extension along a side of the aperture that is adjacent a leading edge of the sliding plate when in the closed position. The resilient panel is configured to at least partially flex to enable the sliding plate to be moved to the closed position when materials are present in the chute, i.e. the materials are not pinched between the sliding plate and a rigid portion of the chute extension. Actuators are coupled between the sliding plate and the base frame to move the sliding plate between the open and closed positions and to positions therebetween. 
     The conveyor is provided to receive materials exiting the hopper through one or more of the gates. A front or discharge end of the individual conveyor of each hopper car is elevated relative to a rear or receiving end thereof. The hopper cars are connected together so that the discharge end of a conveyor of a one car extends over the receiving end of a conveyor on the adjacent car in the direction material is to be conveyed which may be referred to as the forward direction. Material deposited onto the conveyors is sequentially conveyed forward and deposited onto the conveyor of each successive hopper car in the forward direction and then to the offloading car. 
     In a preferred embodiment, the conveyor extends generally horizontally along the length of the hopper and includes an upwardly inclined forward portion that extends a distance upward and beyond the forward end of the hopper car a distance sufficient to overlap a conveyor system of an adjacent car. The conveyor includes a motor for operating the belt and may include sensors for monitoring power usage characteristics of the motor and a sensor for monitoring belt speed of the conveyor. 
     The offloading car includes an operator station, a primary conveyor, and an offloading conveyor. The operator station includes control surfaces and information displays sufficient to enable a single operator to control operation of the material distribution consist. The primary conveyor is configured to receive materials from the conveyor of an adjacent hopper car and to transport the materials to the offloading conveyor. A receiving end of the primary conveyor extends lower than the forward end of the conveyor of the adjacent hopper car. The primary conveyor may include a material scale or weighing system configured to calculate an amount of material transported by the primary conveyor. The offloading conveyor is rotatable or pivotable side-to-side to enable deposition of materials in desired locations alongside the consist or ahead of the consist. The offloading car may also include power sources or generators for providing electrical power to the operator station and/or to drive one or more components of the hopper cars. 
     The generator car includes a generator configured to produce sufficient electrical power to operate the conveyors on each of a plurality of the hopper cars among other equipment that may be included on the consist. A plurality of generator cars may be provided to increase the number of hopper cars that can be included in the consist. The generator car may include one or more conveyors configured to transport materials between hopper cars located forward and aft of the generator car. 
     A control system is provided that enables operation of the material distribution consist by a single operator from the control station. The control system monitors characteristics, such as amperage draw, on each of the conveyor motors to determine the quantity of material being carried by each conveyor. The control system also controls the degree or percentage to which each of the gates is opened or closed based on the quantity of material on the conveyors. Thereby, the control system can relatively precisely control the amount of material disposed on the conveyors from the hoppers and thus the amount of material distributed at a desired location. The operation of the hopper gates may also be controlled such that the conveyors are emptied upon completion of the distribution of the desired quantity of materials. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the invention are described in detail below with reference to the attached drawing figures, and wherein: 
         FIG. 1  is a side elevational view of a material distribution consist depicted in accordance with an embodiment of the invention; 
         FIG. 2  is a side elevational view of a material distribution consist with more than one generator car depicted in accordance with an embodiment of the invention; 
         FIG. 3  is a top plan view of an offloading car of a material distribution consist depicted in accordance with an embodiment of the invention; 
         FIG. 4  is a top plan view of a hopper car of a material distribution consist depicted in accordance with an embodiment of the invention; 
         FIG. 5  is a cross-sectional side view of the hopper car of  FIG. 4  taken along the line  5 - 5 ; 
         FIG. 6  is a perspective view of a hopper gate in a closed position depicted in accordance with an embodiment of the invention; 
         FIG. 7A  is a top plan view of the hopper of  FIG. 6 ; 
         FIG. 7B  is a side elevational view of the hopper of  FIG. 6 ; 
         FIG. 8A  is a top plan view of the hopper of  FIG. 6  in an open position; 
         FIG. 8B  is a side elevational view of the hopper of  FIG. 8A ; 
         FIG. 9  is a cross sectional view of the hopper taken along line  9 - 9  of  FIG. 7A ; 
         FIG. 10  is bottom plan view of the hopper of  FIG. 6  depicted in a partially open position; 
         FIG. 11  is a side elevational view of an angled hopper depicted in a closed position in accordance with an embodiment of the invention; 
         FIG. 12  is a block diagram of a consist control system for a material transport and distribution consist depicted in accordance with an embodiment of the invention; 
         FIG. 13  is a flow diagram depicting a method for offloading a material transport and distribution consist depicted in accordance with an embodiment of the invention; 
         FIG. 14  is an elevational cross-sectional view of a hopper car depicted on a banked curve and including a conveyor guide-roller assembly in accordance with an embodiment of the invention; 
         FIG. 15  is an enlarged perspective view of the conveyor guide-roller assembly of the hopper car of  FIG. 14 ; 
         FIG. 16  is a cross-sectional elevational view of a conveyor with a guide-roller assembly incorporated therewith depicted in accordance with an embodiment of the invention; 
         FIG. 17  is a partial top plan view of two adjacent hopper cars showing conveyors thereof in an overlapping configuration for transfer of material between the hopper cars and showing the hopper cars negotiating a curve depicted in accordance with an embodiment of the invention; and 
         FIG. 18  is a partial side elevational view of the adjacent hopper cars of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter of select embodiments of the invention is described with specificity herein to meet statutory requirements. But the description itself is not intended to necessarily limit the scope of claims. Rather, the claimed subject matter might be embodied in other ways to include different components, steps, or combinations thereof similar to the ones described in this document, in conjunction with other present or future technologies. Terms should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly described. 
     Embodiments of the invention are described herein with respect to the drawings in which reference numerals are employed to identify particular components or features. Similar elements in the various embodiments depicted are provided with reference numerals having matching second and third digits but with differing first digits, e.g. element  10  is similar to elements  110 ,  210 , etc. Such is provided to avoid redundant description of similar features of the elements but is not intended to indicate the features or elements are necessarily the same. Four-digit reference numerals are reserved for description of method steps and do not correlate with the three-digit reference numerals used herein. 
     Embodiments of the invention are described herein with respect to delivery of ballast material, or simply “ballast,” at a desired location along a railway or rail system. However, such is not intended to limit the type of material or applications in which embodiments of the invention might be employed. Terms of relativity, such as forward, rearward, aft, above, below, top, and bottom are used relative to the orientation of the objects included in the drawings and with respect to a forward direction of conveying being from right to left in  FIG. 1  of the drawings. Material is generally described as being conveyed from a rear end or receiving end of a car or conveyor to a forward end or discharge end of a car or conveyor. It is also to be understood that the material distribution consist of embodiments of the invention described herein may travel in either direction. 
     With reference now to  FIGS. 1 and 2 , a material distribution consist  100  is described in accordance with an embodiment of the invention. The material distribution consist  100  includes an offloading car  102 , a plurality of hopper cars  104 , one or more generator/transfer cars  206 , and may include one or more generator cars  106 . The consist  100  may include one or more power or drive cars or locomotives (not shown) that couple to the consist  100  to propel the consist  100  along a rail system or one or more of the cars  102 ,  104 ,  106  may be provided with or include a propulsion system for driving the consist  100  along the rail system. 
     The offloading car  102  includes an operator's station  108 , a primary conveyor  110 , an offloading conveyor  112 , a generator  114 , and a hydraulic pump  116 . The operator's station  108  includes one or more control surfaces, computers, displays, and the like to enable an operator to control operation of components disposed on the offloading car  102  as well as the hopper cars  104  and the generator car  106 . 
     The primary conveyor  110  is positioned near a rearward end of the offloading car  102  and extends at an upward angle toward the forward end of the car  102 . The rear end of the primary conveyor  110  is configured to be at least partially longitudinally overlapped by a hopper conveyor  118  disposed on the hopper car  104  located immediately aft of the offloading car  102  and may extend beyond the rear end of the car  102 . A scale  120  or other weighing device may be disposed on or integrated with the primary conveyor  110  to measure the weight of ballast materials being transported thereby. The forward end of the primary conveyor  110  is supported above an intake end of the offloading conveyor  112 . A chute  122  or other housing may be provided at the forward end of the primary conveyor  110  to direct the ballast materials thereon onto the underlying offloading conveyor  112 . 
     The offloading conveyor  112  is rotatably and pivotably mounted on the offloading car  102 . The intake end of the offloading conveyor  112  is coupled to a rotatable support structure  124  located generally centrally along the length of the offloading car  102 . The support structure  124  is rotatable or pivotable preferably about 180° side-to-side to enable offloading of ballast materials on either side of the offloading car  102 , as shown in  FIG. 5 ; greater or lesser amounts of rotation may be provided. The terms “about” or “approximately” as used herein denote deviations from the exact value by +/−10%, preferably by +/−5% and/or deviations in the form of changes that are insignificant to the function. The offloading conveyor  112  may also be positioned to offload materials in front of the consist  100  or at any desired angle to either side of the consist  100 . The offloading conveyor  112  extends from the support structure  124  in a cantilevered fashion and may be at least partially vertically pivotable about the coupling with the support structure  124  to enable raising/lowering of the discharge end of the conveyor  112 . 
     The generator  114  comprises an available generator technology and may be included on the offloading car  102  to provide electrical power for operation of the controls in the operator's station  108 , operation of the primary and offloading conveyors  110 ,  112 , and/or operation of the hydraulic pump  116 . In another embodiment, the generator  114  is omitted and electrical energy is provided to the offloading car  102  from the generator/transfer car  206  or the generator car  106 , as described more fully below. 
     The hydraulic pump  116  comprises an available hydraulic pump or hydraulic pressure generation system. The hydraulic pump  116  is configured to provide sufficient hydraulic pressure for operation of actuators included on the offloading car  102  as well as those disposed on the hopper cars  104  and/or the generator car  106 . For example, actuators on the offloading car  102  may function to rotate and pivot the offloading conveyor  112  and actuators on the hopper cars  104  may function to open/close gates, as described below. Although the pump  116  and associated actuators and systems described herein are termed hydraulic, other systems, such as electronic, mechanical, and pneumatic, among others can be employed. In another embodiment, the hydraulic pump  116  is disposed on the generator/transfer car  206 , the generator car  106  or on another car in the consist  100 . Appropriate connections are provided between the offloading car  102 , the hopper cars  104 , the generator/transfer car  206 , and the generator car  106  to conduct electricity, hydraulic fluids/pressure, and communications between the cars. 
     As depicted in  FIGS. 1 and 2 , each hopper car  104  comprises a car frame  126  supported on trucks  127  and a car body  128  disposed thereon. The car body  128  includes an outer wall  130  substantially enclosing a hopper  132  and the hopper conveyor  118  therein. The outer wall  130  may form a portion of the walls of the hopper  128  and may aid to contain dust and debris produced by the offloading process and/or to protect the components from the environment. In another embodiment, the hopper car  104  is constructed without the outer wall  130 . In one embodiment, the hopper car  104  is constructed by retrofitting existing bulk freight rail cars, such as open-wagons, box cars, or the like. 
     The hopper conveyor  118  is disposed on the car frame  126  between the car frame  126  and the hopper  132 . The hopper conveyor  118  extends the length of the hopper car  104  and preferably extends a distance beyond each end of the car  104  so as to overlap with conveyors disposed on adjacent hopper cars  104 , the offloading car  102 , or the generator/transfer car  206  described more fully below. 
     In some embodiments, a dedicated end car  104 ′ is provided as depicted in  FIG. 2 . The end car  104 ′ is identical to the hopper cars  104 , but the conveyor  118  disposed therein does not extend beyond a rearward end of the end car  104 ′. As such, the conveyor  118  in the end car  104 ′ will not interfere with or contact other cars coupled to the end car  104 ′; the conveyor  118  in the hopper cars  104  may obstruct coupling with other cars. 
     As shown in  FIG. 5 , the hopper conveyor  118  extends substantially horizontally from the rear end of the hopper car  104  toward the forward end and includes an upwardly angled portion  134  near the forward end of the hopper car  104 . The upward angle and the length of the portion  134  are sufficient to position the forward end of the hopper conveyor  118  above and overlapping with the rearward end of the conveyor on the next adjacent car  102 ,  104 ,  206  as shown in  FIGS. 1 and 2 . The hopper conveyor  118  is preferably a trough-style conveyor in which rollers are provided between upper and lower runs of a conveyor belt  135  to support the upper run of the belt  135  in a generally U-shaped configuration, as shown in  FIGS. 14 and 15 . Each set of rollers generally includes a horizontally extending central roller  139  and two side rollers  141  angled upward and outward from opposite ends of the central roller  139 . It is to be understood that other forms of conveyors are useable in alternative embodiments of the invention. For example, a flat belt conveyor might be employed with sidewalls/guides provided to retain the ballast materials on the belt. 
     Referring to  FIG. 4 , the hopper conveyor  118  includes an electric drive motor  136  drivingly coupled to a drive roller or head roller  137 . Rotation of drive roller  137  rotates the conveyor belt  135 . In some embodiments, the drive motor  136  is configured to enable variable speed operation of the conveyor belt  135 . One or more sensors may be included or associated with the motor  136  and the hopper conveyor  118  generally to monitor one or more characteristics of the conveyor's operation. For example, sensors in the motor  136  may monitor the amperage drawn by the motor  136  or other electrical characteristics of the motor's operation. Another sensor  138  may monitor the speed of the conveyor belt  135  while other sensors might be included to monitor characteristics like the weight of material on the conveyor belt  135 , or a profile of the material on top of the conveyor belt  135 , among a variety of other characteristics. 
     The rear end of the hopper conveyor  118  includes an idler roller  139  around which the conveyor belt  135  rotates and may include an intake guide  140 . As best seen in  FIGS. 17 and 18 , the intake guide  140  is configured to guide ballast received from another conveyor onto the hopper conveyor  118  for transport by the conveyor belt  135  toward the forward end of the hopper car  104 . The intake guide  140  can take a wide variety of configurations, but generally extends a distance laterally beyond the edges of the conveyor belt  135  and may extend a distance longitudinally beyond the end of the conveyor belt  135 . The walls of the intake guide  140  generally slope downwardly toward the upper run of conveyor belt  135  to direct ballast materials toward the center of the belt  135 . 
     The configuration of the forward and rear ends of the hopper conveyor  118  enable transfer of ballast between adjacent hopper cars  104 , and/or to or from other cars  102 ,  206  while the consist  100  is located on a curved section of a rail system, as depicted in  FIGS. 17 and 18 . The hopper conveyor  118  enables transfer of ballast between cars  102 ,  104 ,  206  when positioned on curves in which the heading of immediately adjacent cars  102 ,  104 ,  206  varies by greater than 10° or as much as approximately 20° or more, as depicted by the angle (I) shown in  FIG. 17 , e.g. greater than a 10° curve in the railway. In one embodiment, the hopper conveyor  118  is configured to accommodate curves of up to approximately 13°. 
     The hopper  132  comprises an open space in the upper portion of the hopper car  104  which may be enclosed or open to the environment above the hopper car  104 . The perimeter of an upper part of the hopper  132  is defined by the outer walls  130  of the car  104 . A lower part of the hopper  132  includes inwardly angled sidewalls  142  and a plurality of transverse dividers  144 . The transverse dividers  144  extend between the angled sidewalls  142  and include a pair of sloped faces facing longitudinally forward and rearward and at angles similar to those of angled sidewalls  142 . Preferably the sidewalls  142  and the sloped faces of the dividers  144  are sloped at a downward angle of at least approximately 40° from the horizontal or more preferably between about 50° and about 60°, or about 57°. The downward angle of the sidewalls  142  and the dividers  144  is sufficient to cause the ballast material to flow downward without hanging or collecting on the sidewalls  142  or dividers  144 . Together the angled sidewalls  142  and the transverse dividers  144  divide the lower part of the hopper  132  into a plurality of chutes  146 . Each chute  146  may also be referred to as a hopper such that each hopper car includes a plurality of hoppers. 
     The chutes  146  are generally centrally aligned to overlie the center of the hopper conveyor  118 . Each of the chutes  146  terminates at a lower end to form an aperture or opening  147  through which ballast materials flow. As shown in  FIGS. 4 and 5 , the hopper car  104  includes six chutes  146  although any number of chutes  146  may be included. In the embodiment shown five of the chutes  146  overlie the horizontal portion of the hopper conveyor  118  and are generally aligned within a horizontal plane above the hopper conveyor  118  to place the openings  147  generally within a single horizontal plane. A sixth chute  146  overlies the angled portion  134  of the hopper conveyor  118  and is configured to provide an opening  147  that is inclined to lie in a plane that is substantially parallel to the angled portion  134  of the hopper conveyor  118 . 
     A hopper gate  148  is disposed in or across each of the openings  147  to control the flow of ballast through the respective chute  146 . With additional reference to  FIGS. 5-10 , a hopper gate  148  is described in accordance with an embodiment of the invention.  FIG. 11  depicts a hopper gate  248  configured similarly to the hopper gate  148  but for installation in the angled sixth chute  146  located at the forward end of the hopper car  104 . The features of the hopper gate  248  are thus not described again in detail herein. 
     The hopper gate  148  is formed on a lower end of a chute extension  150  and includes a base frame  152  and a slide plate  154 . The chute extension  150  includes panels  150 S (side),  150 F (front),  150 R (rear) configured to couple to and extend from the respective angled sidewalls  142  and transverse dividers  144  of the chute  146  within which the hopper gate  148  is disposed. The panels  150 S,  150 F and  150 R of the chute extension  150  are preferably disposed at similar angles to that of the sidewalls  142  and dividers  144  but may be provided at one or more steeper or shallower angles. In one embodiment, the base frame  152  of the hopper gate  148  couples directly to the sidewalls  142  and dividers  144  of the chute  146  without the use of the chute extension  150 . As shown in  FIG. 11 , the hopper gate  248  disposed in the forward angled chute  146  of the hopper car  104  includes a chute extension  250  adapted to install the hopper gate  248  in a non-horizontal position. 
     In one embodiment, one or more of the panels  150 S and/or  150 F include a flexible or resilient flange (not shown) coupled to a bottom edge thereof. The resilient flange may aid to better seal between the slide plate  154  and the panels  150 S and/or  150 F to resist material and dust traveling therebetween. The resilient flange may also aid to divert ballast materials flowing therethrough toward the center of the gate opening  160  and thus toward the center of the underlying hopper conveyor  118 . 
     The rear chute extension panel  150 R includes a resilient panel or flange  156  coupled beneath a bottom edge thereof. The resilient panel  156  may be coupled to the rear chute extension panel  150 R or to another member provided by the chute extension  150  or the base frame  152 . The resilient panel  156  is rigidly coupled along a top edge thereof to provide a free hanging bottom edge that can be at least partially flexed in the longitudinal direction of the hopper car  104 . The resilient panel  156  may comprise a rubber, plastic, vinyl, composite, or similar resilient material that is at least partially flexible about a rigid coupling. In another embodiment, the resilient panel  156  is pivotably coupled to the hopper gate  148  and may comprise a rigid plate or sheet of material, e.g. the resilient panel  156  may pivot about its coupling with the gate  148  instead of or in addition to flexing. 
     The base frame  152  is coupled about the lower end of the chute extension  150  and supports the slide plate  154  and one or more actuators  158  for moving the slide plate  154  between closed ( FIGS. 7A-B ) and open ( FIGS. 8A-B ) positions relative to a gate opening  160  formed by the chute extension  150 . 
     The slide plate  154  comprises a generally planar section of rigid material dimensioned to fully close off the gate opening  160 . The slide plate  154  is preferably formed from a material of sufficient strength and durability to support and resist damage from bulky ballast materials during dumping into the hopper car  104  and storage therein. For example, the slide plate  154  may comprise a plate of 0.5 inch thick steel, among a variety of other material options. 
     The base frame  152  is configured to support the slide plate  154  in both the open and closed positions and during movement therebetween. Such configurations accommodate slide plates  154  produced from very heavy, stout, and durable materials, such as heavy gage steel plate, and against very heavy loads produced by large, bulky ballast materials carried by the hopper car  104 . The base frame  152  includes frame members  162 S (side),  162 F (front) that extend about the lateral sides and longitudinal front side of the lower perimeter of the chute extension  150 . The front frame member  162 F extends between the side frame members  162 S along the front side of the chute extension  150  and overlies the slide plate  154 . 
     The side frame members  162 S have a height sufficient to extend below the slide plate  154  and include a pair of spanning members  164  that extend transversely between the side frame members  162 S and beneath the slide plate  154 . The spanning members  164  are located forward and rearward of the gate opening  160  so as not to obstruct ballast flowing therethrough. The spanning members  164  support guide rods  166  that extend between the spanning members  164 . Guide rod extensions  168  are coupled to the forwardly located spanning member  164  and in alignment with the guide rods  166  to operatively extend the guide rods  166  a distance beyond the base frame  152 . Opposite ends of the guide rod extensions  168  are coupled to the structure of the hopper car  104  or to the rearwardly located spanning member  164  of a longitudinally adjacent hopper gate  148 . In one embodiment, the guide rods  166  are continuous and extend beyond the forwardly located spanning member  164  and the guide rod extensions  168  are omitted. 
     As shown in  FIGS. 5-10 , three guide rods  166  and guide rod extensions  168  are provided. It is understood that any number of guide rods  166  and extensions  168  may be employed in embodiments of the invention. Also as shown in  FIGS. 5-10 , the central guide rod  166  extends across the gate opening  160 . Accordingly, the central guide rod  166  can provide additional support to the slide plate  154  to resist flexing or damage caused by heavy loads placed thereon by overlying ballast materials in the hopper car  104 . 
     Referring to  FIG. 9 , the slide plate  154  includes followers or glides  170  coupled to a bottom surface thereof in alignment with the respective guide rods  166  and guide rod extensions  168 . The glides  170  include a follower surface  172  that is contoured to match the contour of the guide rod  166  and guide rod extension  168  and to be slideable therealong. The glides  170  preferably comprise a low-friction material or wear plate, such as a nylon, plastic, brass, or bronze, among others. The glides  170  thus aid the slide plate  154  to slide along the guide bars  166  and extensions  168  between the open and closed positions. In another embodiment, the glides  170  comprise wheels, bearings, or similar components configured to follow the guide bars  166  and extensions  168  and aid movement of the slide plate  154  therealong. 
     The slide plate  154  also includes a drive bar  175  coupled to a trailing edge to extend transversely across the slide plate  154  and beyond the lateral edges thereof. The trailing edge is defined relative to movement of the slide plate  154  toward the closed position with the opposite edge being identified as the leading edge. The actuators  158  each couple between a respective end of the drive bar  175  and a respective side frame member  162 S. The actuators  158  can thus be actuated to move the slide plate  154  along the guide bars  166  and extensions  168  between the open and closed positions. 
     When moved to the closed position, the leading edge of the slide plate  154  contacts the lower edge of the resilient panel  156  or moves beneath the lower edge in close proximity thereto. When contacted, the resilient panel  156  may be at least partially flexed in the direction of movement of the slide plate  154  to allow the slide plate  154  to reach the fully closed position. In either configuration, the flexure of the resilient panel  156  enables the slide plate  154  to reach the fully closed position even when ballast materials are present on a top surface of the slide plate  154  and/or attempting to exit through the gate opening  160 . Unlike known systems in which the ballast materials may become pinched, trapped, or crushed between doors of a gate and/or the sidewalls of the chute thus preventing the doors from achieving full closure, the resilient panel  156  allows flexure between the slide plate  154  and the chute extension  150 . 
     Ballast materials captured between the leading edge of the slide plate  154  and the resilient panel  156  cause the resilient panel  156  to flex or bend outward but do not prevent the slide plate  154  from moving to the closed position. The trapped materials may be retained in position by the force applied by the resilient plate's bias against flexure, may fall out of the hopper  132  onto the hopper conveyor  118 , or may be forced back into the hopper  132  by the resilient plate's bias. The resilient panel  156  resists substantial further exit of ballast materials from the hopper  132 . The resilient panel  156  thus resists the ballast materials from exiting the hopper  132  when the slide plate  154  is in the closed position while also allowing the slide plate  154  to move to the closed position without binding on the ballast materials. 
     As shown in  FIG. 5 , the hopper car  104  includes a control device  173 , such as a computer, programmable logic controller, or similar programmable control unit. The control device  173  may be in electrical communication with control systems housed in the operator's station  108  on the offloading car  102  and may receive commands therefrom. The control device  173  is configured to monitor the operation of the hopper conveyor  118  and the hopper gates  148 ,  248  on the respective hopper car  104 . A control device  173  is preferably provided on each hopper car  104  for control of the individual operations thereof. In another embodiment, control systems may be provided elsewhere on the consist  100  and configured to monitor the operation of each individual hopper car  104 . Dedicated control devices  173  on each hopper car  104  may provide additional fail-safes and more reliable control of the operations of the hopper car  104  due to potential communication issues that may arise between cars  102 ,  104 ,  106 ,  206 . Operation of the hopper car  104  and control device  173  is described more fully below. 
     The generator car  106  includes one or more generators  174  and may include a storage bin  176 . The generator(s)  174  are configured to produce sufficient electrical energy for powering the hopper conveyors  118  on the hopper cars  104  among other components disposed on the material distribution consist  100 . The storage bin  176  comprises a structure configured to house tools, equipment, crew quarters, or other desired gear that may be needed or used by the operator of the consist  100 . 
     As shown in  FIG. 2 , the generator car  106  may be positioned at the trailing end of the consist  100  so as not to interrupt the transport of ballast materials along the length of the consist  100 . In another embodiment shown in  FIGS. 1 and 2 , a generator/transport car  206  may be provided. The generator/transport car  206  is configured similarly to the generator car  106  but includes a conveyor  178  similar to the hopper conveyors  118 . The conveyor  178  is configured to pass beneath the generator  174  or might be configured to pass alongside or over the generator  174  to transport ballast materials received from the hopper car  104  located rearward of the generator/transport car  206  to the hopper car  104  located forward of the generator/transport car  206 . The generator  174  and the storage bin  176  (if included) may be raised or suspended above the conveyor  178 . The generator/transport car  206  may also include additional hydraulic pumps or the like as necessary to operate the associated systems of the consist  100 . 
     In an embodiment, the generators  174  are configured to provide sufficient electrical power for up to a predetermined number of hopper cars  104 . For example, the generator  174  might be configured to power up to thirty hopper cars  104 . As such, additional generator cars  106  or generator/transport cars  206  are added to the consist  100  for each additional set of up to thirty hopper cars  104 ; each additional set of hopper cars  104  being coupled to the rear end of the consist  100 . Preferably, the hopper cars  104  are arranged in sets of thirty hopper cars  104  with a generator/transport car  206  disposed halfway through the set, e.g. fifteen hopper cars  104  followed by a generator/transport car  206  followed by another fifteen hopper cars  104 . Additional sets of hopper cars  104  and generator/transport cars  206  can then be coupled to the end thereof. It is understood, that other numbers of hopper cars  104  and generator/transport cars  206  may be combined without departing from the scope of embodiments of the invention described herein. Accordingly, the number of hopper cars  104 , and thus the capacity, of the consist  100  can be customized to a given application as desired. 
       FIGS. 14, 15, 16  depict a guide-roller assembly  184  configured to enable operation of the hopper conveyor  118  for offloading of ballast materials while one or more of the hopper cars  104  are parked or positioned on a banked curve in the railway. Due to the banking of the curve, the rails and thus the hopper car  104  may lean or tilt to one side at an angle θ relative to the horizontal. The tilting of the hopper car  104  also tilts the hopper conveyor  118  to the side and may create a bias due to gravity on the conveyor belt  135  to move toward the downslope side of the hopper car  104  when moving about the hopper conveyor  118 . The guide-roller assembly  184  includes a plurality of feed run guide-rollers  185  and a plurality of return run guide-rollers  186  that retain the conveyor belt  135  in a desired operational position on the hopper conveyor  118 . 
     The feed run and return run guide-rollers  185 ,  186  may be disposed in sufficient numbers and at selected positions along the length of the hopper conveyor  118  as necessary to sufficiently retain the conveyor belt  135  in the operational position. The guide-rollers  185 ,  186  may be evenly spaced along the length of the conveyor belt  135 , clustered in problem areas, or otherwise arranged. The position of the feed run guide-rollers  185  may correspond with that of the return run guide-rollers  186  or may differ. 
       FIG. 16  depicts one exemplary configuration of the guide-rollers  185 ,  186  on the hopper conveyor  118 . As shown, the feed run guide rollers  185  are generally evenly spaced in pairs along the length of the central portion of the hopper conveyor  118 . A cluster of four feed run guide-rollers  185  is disposed along the angled section  135  of the conveyor  118  and a cluster of three guide-rollers  185  is disposed adjacent an opposite intake end of the conveyor  118 . The return run guide-rollers  186  are more sporadically spaced along the return run of the conveyor belt  135 ; a cluster of three guide-rollers  186  are disposed adjacent the intake end of the conveyor  118 , with two single guide-rollers  186  spaced apart and away from the intake end, and two pairs of guide-rollers  186  spaced further along the length of the hopper conveyor  118 . 
     As depicted in  FIGS. 14 and 15 , the feed and return run guide-rollers  185 ,  186  include a roller body  187  with an axle  188  extending from one end thereof coaxially with the axis of rotation of the roller body  187 . A bearing assembly (not shown) is disposed within the roller body  187  to enable rotational motion of the roller body  187  relative to the axle  188 . In another embodiment, the axle  188  is rotationally fixed relative to the roller body  187  and may be coupled to a bearing assembly (not shown) disposed on the hopper conveyor  118  to enable rotational motion of the axle  188  relative to the hopper conveyor  118 . The roller body  187  includes an hourglass shape in which a sidewall  189  thereof is inwardly recessed to form a circumferentially extending groove. It is understood that other roller configurations may be employed without departing from the scope of embodiments of the invention. 
     The guide-roller assembly  184  includes upper and lower mounting assemblies  190 ,  191  that couple the feed run and return run guide-rollers  185 ,  186  respectively to the hopper conveyor  118 . The mounting assemblies  190 ,  191  preferably couple to support members  192  that support one or more rollers, e.g. the side rollers  141  and central rollers  139 , of the hopper conveyor  118 . Or the mounting assemblies  190 ,  191  may couple to the frame of the hopper conveyor  118  or of the hopper car  104 . 
     The mounting assemblies  190 ,  191  enable adjustment of the position of the feed run and return run guide-rollers  185 ,  186  in at least one direction. For example, the mounting assemblies  190 ,  191  may enable adjustment of the position of the guide-rollers  185 ,  186  in an axial direction, or longitudinally or laterally relative to the hopper conveyor  118 . 
     The guide-rollers  185 ,  186  are preferably positioned to contact an edge of the conveyor belt  135  at a location generally centrally within the groove in the sidewall  189 . The guide-rollers  185 ,  186  may be in constant contact with the conveyor belt  135  or may only contact the conveyor belt  135  when the belt  135  drifts away from a normal position. Accordingly, when the hopper car  104  is tilted at the angle θ, the conveyor belt  135  may tend to drift toward the downslope side of the hopper car  104 . The edge of the conveyor belt  135  may thus come into contact with the feed run and/or return run guide-rollers  185 ,  186  and be prevented from drifting out of an operational position by the guide-rollers  185 ,  186 . 
     The feed run guide-rollers  185  and the return run guide-rollers  186  can be similarly positioned to define an operational position window in which the conveyor belt  135  is retained. Or one or more of the feed run or return run guide-rollers  185 ,  186  may be positioned to train the conveyor belt  135  or bias the conveyor belt  135  toward a desired operational position. In one embodiment, the feed run guide-rollers  185  are positioned to define a maximum operational position window in which the conveyor belt  135  shall be operated while the return run guide-rollers  186  are positioned closer to the edges of the conveyor belt  135  to guide the belt  135  into a more specific operational position. 
     Training or realigning the conveyor belt  135  is preferably completed on the return run using the return run guide-rollers  186  because the belt  135  is not loaded with material and is in a generally flat state, e.g. not a trough, and is thus more easily urged toward the desired operational position. For example, the configuration of the guide-rollers  185 ,  186  depicted in  FIG. 16  provides sufficient control of the feed run of the conveyor belt  135  to maintain the belt  135  in an operational position when unloading materials while the hopper car  104  is on a banked curve and enables realignment of the conveyor belt  135  on the return run by the return run guide-rollers  186 . 
     With reference now to  FIG. 12 , operation and control of the material distribution consist  100  is described in accordance with an embodiment of the invention. A consist control system  180  is provided, such as in the operator's station  108  to provide overall control of operations of the consist  100 . The consist control system  180  may include one or more computing devices, programmable logic controllers, or other devices suitable to execute routines, provide commands, monitor conditions, operate machines, and otherwise oversee and control operations of the consist  100  and the components thereon. 
     As described previously, each hopper car  104  includes a control device  173  disposed thereon. The control device  173  is in communication with or is operable to control the conveyor drive motor  136  and each of the hopper gates  148  individually. One or more sensors  182  associated with the hopper conveyor  118  and/or the hopper gates  148  provide signals to the control device  173  indicating state and/or operating conditions of the respective conveyor  118  or hopper gate  148 . Additionally, the belt sensor  138  associated with the hopper conveyor  118  provides a signal to the control device  173  indicating the speed or movement of the conveyor belt  135 . The control device  173  may also be in communication with one or more of the other control devices  173  of each of the other hopper cars  104 . Communications between control devices  173  may be direct or may be routed through the consist control system  180 . 
     The control device  173  may control operation of the hopper conveyor  118  in a master-slave fashion as instructed by the consist control unit  180 . However, the control device  173  may be authorized to act independently and/or to supersede commands from the consist control system  180  when a fault condition occurs. In such a condition, the control device  173  of a first hopper car  104 , e.g. hopper car #1, may operate as an interlock or fail-safe to restrict or control operations of one or more hopper cars  104  positioned further up the path of material flow, e.g. hopper car #'s 2 through N. Accordingly, when the control device  173  of hopper car #1 senses a fault condition, the control device  173  of hopper car #1 can stop operations thereon and can signal to hopper cars #2-N to stop operations as well. 
     In one exemplary instance, ballast material is being transported from hopper car #2 to hopper car #1 and on to the offloading car  102  along the respective hopper conveyors  118 . The control device  173  on hopper car #1 determines that the conveyor motor  136  on hopper car #1 is operating at the desired speed as indicated by the sensor  182  but that the speed of the conveyor belt  135  is indicated to be zero feet/second by the belt sensor  138 . Such a condition may be present when the belt  135  has broken and is thus no longer moving but the motor continues to turn or when the belt  135  has been overloaded and the drive wheel of the conveyor motor  136  is slipping. The control device  173  of hopper car #1 identifies this condition as a fault condition and immediately stops operation of the hopper conveyor  118  on hopper car #1 and may close any hopper gates  148  to restrict further ballast material from flowing therefrom. The control device  173  of hopper car #1 also signals the control device  173  of hopper car #2 to indicate the fault condition and cause operations of the conveyor  118  on hopper car #2 to be halted and the gates  148  to close. The operation of the conveyors  118  of each successive hopper car  104  are then halted and the gates  148  closed in a cascading fashion. As such, the overall operation of multiple, successive hopper cars  104  can be halted by the control device  173  of hopper car #1 and a pileup of materials between successive hopper cars  140  can be avoided. 
     Referring now to  FIG. 13 , a method  1300  for operating the consist  100  is shown and described in accordance with an embodiment of the invention. The consist  100  is typically first loaded and transported to a location at which a desired amount of ballast materials are to be offloaded. The ballast materials may be offloaded while the consist  100  is stopped or while the consist  100  is in transit along the tracks. The ballast materials are offloaded alongside the rails for later distribution or installation by a rail maintenance crew. For example, the crew may replace ballast materials under the tracks, dump new or additional ballast on an embankment, or line a drainage system with new materials. The ballast materials might also be offloaded in front of the consist  100  or behind the consist  100  depending on the direction of travel thereof. A plow may be provided to aid movement of the offloaded ballast materials to a desired location or depth and/or to ensure the rails are clear for travel of the consist  100  when offloading in front of the consist  100 . 
     Once on location, one or more of the hopper conveyors  118 , the primary conveyor  110 , and the offloading conveyor  112  are started. Depending on the sequence by which the hopper cars  104  are to be unloaded, the conveyors  118  on all or only a portion of the hopper cars  104  may be started. For example, if the hopper cars  104  are to be unloaded from the front of the consist  100  to the rear, then only the conveyor  118  of the first hopper car  104  need be started. 
     The operator in the operator's station  108  controls the offloading process via the consist control system  180 . The operator may provide one or more inputs to the system  180  indicating how much ballast material is to be offloaded, an offloading run-time, a number of hopper cars  104  to be offloaded, among a variety of other inputs. In one embodiment, the consist control system  180  is provided with a total weight or mass of ballast material to be offloaded. The consist control system  180  may calculate appropriate offloading characteristics to ensure the proper amount of ballast material is offloaded. For example, the system  180  may be provided with an amount of ballast material in each hopper car  104  or an amount of time required to offload a particular amount of ballast among other data upon which to calculate the offloading parameters. In one embodiment, the system  180  employs the scale  120  in the primary conveyor to aid in determining the amount of ballast material that has been offloaded. The consist control system  180  may also track or identify the amount of ballast material residing on the conveyors  110 ,  112 ,  118  at a given time in order to determine when to close the hopper gates  148  so as to offload the desired amount of ballast while also finishing the process with the conveyors  110 ,  112 ,  118  being empty. 
     A first hopper gate  148  is at least partially opened at step  1304 . The consist control system  180  can cause the gate  148  to be opened directly or the system  180  may instruct the control unit  173  on the respective hopper car  104  to open the gate  148 . The hopper gate  148  is preferably only partially opened. In one instance, the actuators  158  are operated for a predetermined time that corresponds to movement of the slide plate  154  a given predetermined distance. A predetermined time delay is then observed to allow ballast materials to flow from the hopper  132  onto the hopper conveyor  118 , as indicated at step  1306 . 
     At step  1308 , one or more characteristics of the operation of the hopper conveyor  118  are identified. For example, the conveyor operation sensors  182  may sense an amperage drawn by the conveyor motor  136 . The amperage drawn by the motor  136  may be indicative of a load placed on the motor  136  and thus an amount of ballast material that has been deposited on the conveyor belt  135 . If the identified characteristic of the conveyor motor  136  indicates that the conveyor  118  is fully loaded or is loaded within a desired level (step  1310 ), e.g. the amperage drawn is greater than a specified amount, then the method returns to step  1306  and an additional time delay is observed. The additional time delay may be of the same or different duration to the initial time delay. 
     If the characteristic shows that the conveyor  118  is not loaded to a desired level (step  1310 ), e.g. the amperage drawn is less than a specified amount, and the hopper gate  148  is not in a fully opened state (step  1312 ) then the hopper gate  148  is opened by an additional increment, as indicated at step  1314 . The additional increment may be based on an additional energizing of the actuators  158  for a given time or a movement of the slide plate  154  a predetermined distance. The method then returns to step  1306 . Alternatively, if the characteristic shows that the conveyor  118  is overloaded, e.g. the amperage drawn is greater than a predetermined level, then the hopper gate  148  may be closed by a predetermined increment, as indicated at step  1316 . The increment can be the same or different than the increments by which the gate  148  is opened. The method then again returns to step  1306 . 
     If the hopper gate  148  is in a fully opened state (step  1312 ) then the process begins again with the next hopper gate  148  to be unloaded, as indicated at step  1318 . The hopper gates  148  may be opened one-at-a-time or multiples-at-a-time on the same or on multiple hopper cars  104 . The gates  148  can be opened in sequence from front to back of the consist  100 , in the reverse, or at various intermittent locations along the consist  100  as desired. Additionally, the hopper gates  148  may be closed following step  1316  or may remain open. In one embodiment, the gates  148  remain open until the hopper car  104  is determined to be empty or until the consist  100  is determined to be empty. 
     At any point in the method  1300 , the consist control system  180  may determine that the desired quantity of ballast materials have been released from the hoppers  132 , e.g. the quantity of ballast materials offloaded by the offloading car  102  and present on the conveyors  118  is equal to or greater than the desired quantity. The system  180  may thus instruct any open hopper gates  148  to be closed to stop the flow of ballast materials onto the conveyors  118 . The control devices  173  of the respective hopper cars  104  may thus cause the hopper gates  148  to be closed by actuating the actuators  158  to move the slide plates  154  to the closed position. In doing so, the resilient panels  156  enable the slide plates  154  to move to the closed position to stop the flow of ballast materials without binding or crushing the ballast materials between the leading edge of the slide plate  154  and the chute extension  150  as described previously above. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of the technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Identification of structures as being configured to perform a particular function in this disclosure and in the claims below is intended to be inclusive of structures and arrangements or designs thereof that are within the scope of this disclosure and readily identifiable by one of skill in the art and that can perform the particular function in a similar way. Certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations and are contemplated within the scope of the claims.