Patent Publication Number: US-2003226470-A1

Title: Rail transport system for bulk materials

Description:
BACKGROUND OF THE INVENTION  
       [0001] This invention relates to a method and apparatus for moving bulk materials that can be moved in conventional trains, trucks, conveyor belts, aerial tramways or as a slurry in a pipeline. All of the above methods are commonly used in various industries because of site specific needs or experience. In the minerals and aggregate industries, for example, bulk materials were moved from mining or extraction sites to a process facility for upgrading or sizing  
       [0002] Trucks had been the system of choice for many years for moving bulk materials. Trucks were enlarged to allow more efficient transport of bulk materials as labor, maintenance and fuel costs increased.  
       [0003] Trains have been used for many years for bulk material transport in hopper cars. Because of the use of rolling iron wheels on steel tracks they are very efficient users of energy but are limited in capacity relative to the drivers or locomotives. Large tonnage, long trains use multiple drivers that are heavy units and these dictate the weight of rail and ballast requirements. All railroads are designed for the weight of drivers or locomotives and not the loads, which are significantly less. Rail cars are individual units that have to be loaded in a batch process, one car at a time. Because of weight and driver requirements all rail cars are operated in a relative flat plane because of height to width ratios. Bulk materials can be unloaded from hopper cars by opening bottom dump hatches or can be individually rotated to dump out the top. In all cases, the cars are loaded and unloaded in a series of batch operations.  
       [0004] Although moving from point A to point B by railroad is cost effective, the added cost of batch loading and unloading stages in shorter distance transports reduces the rail cost effectiveness.  
       [0005] Conveyor belts have been used for many years to move bulk materials. A wide variety of conveyor belts exist that can move practically every conceivable bulk material. Very long distance single belt runs are very capital cost intensive and are subject to catastrophic failure when the belt tears or rips, shutting down the whole system and dumping the carried load. Conveyor belts are relatively energy efficient but can be high maintenance items because of multiple bearings in the idlers required to maintain the troughed configuration of a belt. Short distance conveyor belts are very commonly used in dry or damp transport of almost all types of materials. Because conveyor belts are normally operated fairly flat they are not effective at transporting relatively high solids slurry that water can drain off of and thus create a spilled water handling problem.  
       [0006] Some bulk materials can be transported in pipelines when mixed with water to form a slurry that is pushed or pulled with a motor driven pump impeller in an airless or flooded environment. The size of the individual particles that are present in the bulk materials dictates the transport speed necessary to maintain movement. For example, if large particles are present then the velocity must be high enough to maintain movement by saltation or skidding along on the bottom of the pipe of the very largest particles. Because pipelines operate in a dynamic environment friction is created with the stationary pipe wall by a moving fluid and solid mass. The higher the speed of the moving mass the higher the friction loss at the wall surface requiring increased energy to compensate. Depending  
       [0007] on the application, the bulk material has to be diluted with water initially to facilitate transport and dewatered at the discharge end if the product moved is a finished product. In cases where further wet processing is required of the bulk material, this slurry form can facilitate further processing.  
       [0008] Narrow gage railroads for transporting bulk material from mines and the like is known from U.S. Pat. No. 3,332,535. The patent shows a light rail train made up of several cars propelled by drive wheels  13  and electric motors  14 .  
       [0009] In U.S. Pat. No. 3,752,334 a similar narrow gage railroad is disclosed wherein the cars are driven by an electric motor  40  and drive wheels  42 .  
       [0010] A review of the above described transport methods indicates that they all have specific advantages over the others dependent on the application. It has become apparent however that increases in labor, energy and material costs plus environmental concerns that alternative transport methods need to be applied that are energy and labor efficient, quiet, non-polluting, and esthetically unobtrusive. The light rail unitized open trough train of this invention offers an innovative alternative to the above mentioned material transport systems.  
       SUMMARY OF THE INVENTION  
       [0011] Accordingly, it is an object of the present invention to provide a method and apparatus for the efficient transport of bulk material that utilizes light rails similar to, but smaller than conventional railroad rails of sufficient capacity to support the carrier and  
       [0012] the load. The invention comprises a combination of a railway train with external drivers for transporting bulk commodities. The train consists of a plurality of cars coupled together on  
       [0013] a trackway with each car having a longitudinal trough adapted to contain said bulk commodities and each car having a pair of car length side drive plates, a pair of drive motors mounted adjacent to and on both sides of said trackway which consist of AC electric motors with drive means to provide frictional contact with said side drive plates, and an AC inverter and controller connected to every pair of drive motors whereby the motors are synchronized and both the voltage and frequency can be raised or lowered as needed.  
       [0014] In the present invention, there are external or off-track drivers thus reducing the need for costly ballast and sleepers to support the drivers with the train and the load. For the purposes of this invention, light rails are those having a weight of 60 or less pounds per yard of length.  
       [0015] Another aspect of this invention is a method of transporting bulk commodities by a light rail train with external drivers with the steps of coupling a plurality of railway cars together to form a train on a trackway wherein each car has a longitudinal trough adapted to contain the bulk commodities and each car has a pair of car length side drive plates, loading said train with bulk commodities, driving said train with one or more pairs of drive motors mounted adjacent to said trackway, and unloading the train by inverting the cars on an arcuate dual trackway.  
       [0016] The cars each consist of an open trough and when joined or coupled together represent an open continuous trough for the entire length of the train. A flexible sealing flap overlaps the space between each individual car so that the train can follow the terrain and curves with out losing its integrity as a continuous trough. The material to be transported in the train is effectively supported and sealed by this flap as the material weight holds it tight against the trough in the forward car. The long continuous trough provides for simplified loading as the train can be loaded and unloaded while moving similar to a conveyor belt. This is a significant advantage over the batch loading equipment requirements of a conventional railroad hopper car.  
       [0017] Each car will have a fixed side drive plate on each side which runs the length of the car and spaced outside the wheels and tracks. These side drive plates are located symmetrically with the wheels and parallel to the light rails. Preferably, the centerline of the wheels will bisect the drive plates.  
       [0018] By providing two parallel sets of rails such as an upper and lower set of rails at the dumping station, the train can operate inverted with the train hanging on the lower rail for unloading. Effectively, the train can make an outside loop with a double set of rails, which greatly simplifies unloading. After dumping, the inverted train can then be rotated back to the normal position and allowing elimination of the upper set of rails.  
       [0019] After the lead car, the individual cars have one set of wheels and a single point connecting it to the car in front such as brackets with clevis pins. This allows the train to move in a flexible manner as well as vertically and actually rotate when operating in an  
       [0020] inverted position to return to the normal operating condition. This ability to be less terrain sensitive than a conventional train adds to the flexibility of this light rail transport system.  
       [0021] The static drive stations consist of alternating current electric motors each coupled to a gear reducer which rotates a drive tire which is in contact with the aforementioned side drive plates of the individual cars. Each station will consist of two or multiple of two drive units rotating in opposite directions on opposite sides of the cars. The AC electric motors are controlled by inverters and controllers, which allow speed variations of the drive stations as required. The inverter, controller and gear reducer design will allow operation of the drive station in reverse so that a train can be moved in both directions on the same track. This feature is important in single-track mining operations. Each drive station motor operates in a vertical axis with the drive tire horizontal and contacting the drive plates. Each drive station is mounted to allow rotation around a fixed pivot shaft and can be pivoted by an external jack to control contact pressure on the side drive plates of the cars. This jack can be either electrically or mechanically controlled to provide the required opposing pressures to provide forward thrust without slipping.  
       [0022] The drive stations can be shut down when not needed. A sensor in the operations control center advises the drive unit when a train is approaching and then starts up that drive. When the train passes the drive station it will then shut down. The use of AC electric motors on the drives that are stationary allows for more efficient maintenance and safety as the energy to operate each drive is from a insulated power cable as opposed to the open third rail or overhead bare cable used in typical electric drive trains.  
       [0023] Maintenance of the drive stations is simplified by the ease of removing a whole unit, when damaged, by lifting it off its pivot post and inserting a new unit. The side drive plates are designed to maintain continuity of tire to plate contact between cars by providing a projection in the lower part of the side plate and a matching recess in the lower part of the next car. It is preferred to use a semi-circular shaped projection but other shaped can be used if desired. The tire is always in contact with the upper part of the forward car plate when it comes in contact with the lower part of the following car plate. This design reduces vibrations when the drive wheel passes from one car to the next. These plates are also designed to allow short radius outside loops between cars as well as space for turning or rotating as part of the operating process.  
       [0024] The wheels of each car are inside the side drive plates. These wheels are attached by a short shaft from the inside of the main frame to the drive plate. If desired, a single axle with wheels can be mounted through the frame. This allows for easy replacement of wheels and bearings when required.  
       [0025] The drive tires can be made out of a variety of materials. Examples of suitable materials are solid rubber tires, synthetic rubber tires, urethane pneumatic rubber tires and synthetic foam filled rubber tires. The preferred tire is a foam filled pneumatic tire. The foam provides the flex function associated with air filled tires without the potential problem of rapid deflation. The flexing capability compensates for irregularities in car side plate spacing and also allowed for full contact of straight side plates even in deformed sections that would lead to contact skips with nonflexible tires. The use of a deflatable tire could cause a loss of traction and potential for derailment. The utilized tire will have a relatively  
       [0026] low durometer surface that can adjust to the slight variable in the surface of the side plate providing positive traction. The tire and wheel need to be permanently attached to avoid slippage during high torque startup when the unit train is idle and loaded.  
       [0027] Forward or reverse motion of the train is the result of rotation of dual horizontal tires on opposite sides of the train turning in opposite directions with suitable pressure of said rotation that provides minimal slip between the tire surface and side plates. In other words, the two opposing tires are both pushed inward toward the center of the track. The friction of these drive tires is sufficient to avoid slippage between the drive tires and side plates, hence providing thrust.  
       [0028] The drive tire is mounted on a vertical shaft that is part of a gear reducer interconnected to an electric motor. This motor, gear reducer and tire unit or drive system is mounted on a base that is offset from the centerline of the drive system which allows it to rotate around the vertical post. The vertical post is approximately the same distance from the car side plates as one half of the diameter of the tire. This spacing allows for most efficient pressure when forces are applied to the side plates.  
       [0029] Control of side pressure to maintain adequate friction between the side plate and the tire is maintained by the placement of a second vertical post aligned perpendicular to the side plates of the cars and aligned with the drive tire. A tube containing a jack-screw type of device is attached to the second vertical post that provides for movement of the drive tire against the car drive plates. Side pressure is maintained by adjusting the jack-screw either forward or reverse dependent on the needs with a fixed support bracket that is attached to the jack-screw containing tube. The adjustment of the jack-screw is  
       [0030] made by either a manually controlled jack handle or an electric motor that is reversible. With proper sensing devices the side plate pressures can be controlled remotely from a central location with an electrical control system.  
       [0031] Any gear reducer attached in line or perpendicular to the motor and ending with a vertical shaft for attachment with the drive tire will function for this application. To maintain simplicity the in line system is preferred for ease of pressure adjustments. It is preferred to operate with a drive that is able to withstand substantial shock loads in cases where power failures occur while the train is in motion or when it impacts a powerless drive station. It is also important to have a gear reducer that is able to function with high startup torque loads that occur on loaded train startups. The preferred drive is the SM cyclo concentric type gear drive from Sumitomo Heavy Industries that operates in a manner to meet the shock load and high torque startup requirements. It is to be noted that conventional gear reducers with inner-locking gear teeth can be subject to malfunctions when high shock loads are applied.  
       [0032] An important part of the drive system is the application of an inverter and controller system. An inverter can control both frequency and voltages applied to alternating current systems. The inverter and controller supplies line voltage and then distributes this voltage to opposing pairs of drive motors. The ability to control both frequency and voltage distribution is important in the synchronized operation of two drive motors and consistent speed of the opposing drive tires. The inverter system also can be used as a switch to control electric power and direction to the drive motors.  
       [0033] An AC inverter control synchronizes the rotational speed of both drive tires at a  
       [0034] drive station. All the other drive stations are also set to operate at the desired rotational speed. By synchronizing all the drives, operational speed is consistent and smooth transfer of energy occurs from one station to the next and this provides even train movement. All drive stations controls can be set for local or remote operation. By use of the remote setting each AC Inverter can be controlled and monitored from a central control station through a cable or radio signal control system. Controlled speed changes can be made from this remote station if operational modifications are necessary. The Inverter control system also provides the means of placing the drives in a standby position from which a sensor on the track signals the arrival of a train, starts the drive to operational speed and shuts down the drive after the train clears that drive station. This continues around the track as the train makes a complete loop. By only operating when a train is present, energy usage is kept to a minimum.  
       [0035] A sensor attached to the track or at any location prior to the drive station can acknowledge or detect the presence of an arriving train that transmits a signal to the inverter control system to provide power to the drive motors so that upon entering the drive station, the drive tires rotational velocity is the same as the train speed. In addition, upon exiting a drive station an additional sensor can provide a signal that allows the inverter control system to shutdown the drive motors.  
       [0036] The use of the inverter control system also allows for a controlled rate of start up speed if the system is shut down for any purpose. If required, the inverter internal switch system can also allow the drive stations to operate in reverse, if backing up the train is required. The unique combination of both mechanical and electrical drive controls and  
       [0037] motor control functions represents a very energy efficient system previously not available on earlier drive systems.  
       [0038] Energy is only used when the train is physically entering the drive station. This concept allows each drive station to operate independently of the other stations. Information on a stations status as to operating temperature, torque load, rotational speed and other status requirements can be transmitted on a multifunctional control and information cable or by radio signals to a central control station. Once programmed, the entire system will operate hands free with no direct operational control necessary.  
       [0039] In addition to the unique drive system the relationship of the drive plate to the car wheel is important. Locating the side drive plates symmetrical to the free rolling wheel gives access to a rail on both the bottom and top of the wheel. This allows operation of the train in an inverted position by using two sets of parallel rails on both sides of each wheel. With four rails the train is encapsulated because of the flanged wheel side movement limitations and minimal space between the parallel rails only slightly wider than the wheel diameters.  
       [0040] The rails can be bent to provide for a radius that would allow the cars to operate in an outside loop where both the top and bottom of the wheels are in near physical contact with the parallel rails. At the completion of an approximate 180-degree loop the cars would be inverted.  
       [0041] A flexible flap is attached to the leading edge of each car. This flap would overlap but not be connected to the trailing edge of the forward car. During normal transport the weight of the material on the car forces the flap against the trough in the forward car,  
       [0042] preventing leakage. Because of the material in the flap being flexible, the cars can twist and turn without losing sealing integrity.  
       [0043] When operated in an outside loop the spacing between the individual car troughs opens up as the cars pivot around the clevis pin attachment. The rotary motion of the outside loop causes the lead car to drop away from the trailing car separating the flexible flap from the forward car. The flap in this environment performs the function of a spout or chute as the material slides off the front of the car, it is projected over the car in front. Once the carried material slides off the car and spout formed by the flap, self-cleaning of the cars occurs. The combination of dumping speed and car flap trough extension allows for precise dumping without impact of the leading car with dumped material.  
       [0044] With the outside loop completed and the cars emptied, it is necessary to rotate the train back to the normal upright position or 180 degrees. This rate of twist is dependent on space available and still requires four sets of track to encapsulate the wheels. For ease of installation, round steel stock can be substituted for rail in this application. Once the train is inverted after dumping the flaps will again lay flat against the trough of the leading car. With the addition of new feed material from a loading station the cycle is repeated. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0045]FIG. 1 shows a perspective view of the train with the leading car in front, as it passes through one of the drive stations from right to left.  
     [0046]FIG. 2 shows the same train in more detail without the drive station.  
     [0047]FIG. 3 is a top view of the leading car with the cargo-carrying trough removed.  
     [0048]FIG. 4 is a top view of the remaining cars in the train with the trough removed.  
     [0049]FIG. 5 is an end view of one of the drive stations without the train.  
     [0050]FIG. 6 is a top view of one of the drive stations.  
     [0051]FIG. 7 is side view of the dumping station for the train.  
     [0052]FIG. 8 is cross-sectional view of FIG. 7 taken on section A-A.  
     [0053]FIG. 9 is a diagrammatic view of the dumping station showing the placement of the flaps 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0054] FIGS.  1 - 9  illustrate the invention but with regard to the reverence numerals used therein, the following index is presented to facilitate a better understanding of the numbering system used throughout all the figures.  
                                      2   light rail train tracks       4   steel drive station plate or concrete slab       5   caps for support posts       6   vertical support post       7   brackets for support posts and driver pivot           posts       8   hand crank or motorized crank       9   crankshaft       10   electric drive motor       11   driver pivot post       12   drive tire       13   gear reducer       14   car trough       15   end plate for trough on first and last cars       16   side plate for lead car       17   tapered side plate for lead car       18   polyurethane flexible flap       19   side plate for intermediate cars       20   car wheel       21   side plate for rear car       22   vertical support bracket for trough       23   upper support bracket for trough       24   semi-circular front portion of side plate       25   lead car front axle       26   rear semi-circular opening in side plate       27   rear axle for cars       28   AC inverter and controller       29   access door       30   cross braces       32   rear brackets for           clevis pin       34   front bracket for clevis pin       36   main support beams       37   inverter base       38   support bracket for dual rails in dumping           station       40   locking nut for axle       42   threaded axle support       44   support posts       46   concrete footing       47   front-end loader       50   transported product                  
 
     [0055] From a consideration of FIGS. 1, 5 and  6 , it is clear that light rails  2  are mounted on a base plate  4 , which can be a thick steel plate or a concrete slab of suitable thickness. Vertical support posts  6  and pivot posts  11  are mounted on the base  4  with one or more support brackets  7 . Each support post  6  has a cap  5  on which is mounted the crankshaft  9 .  
     [0056] The drive wheels  12  are powered by the AC electric motors  10  which are directly coupled to gear reducers  13 . The AC electric motor preferably operates on 480 volts and has a speed of 1780 revolutions per minute (RPM). In order to achieve more power, the gear reducers lower the speed to a range of 50 to 250 RPM and preferably in the range of 75 to 125 RPM. The pressure of the wheels  12  on the car side drive plates  16 ,  17 ,  19 , and  21  is adjusted by means of a hand crank  8 . Each motor  10  is mounted on a pivot post  11  and swings around the pivot post in small increments to adjust the wheel pressure in accordance with movement by the hand crank  8 . If desired, the hand crank  8  can be replaced with a small reversible electric motor with remote controls.  
     [0057] The train is shown in FIG. 2 wherein the car tough  14  has end plates  15  on the front of the first car and on the rear of the last car. The train can be made as long as is needed by merely adding more middle cars and more driving stations. The effect of this is to create a long moving trough of bulk material.  
     [0058] It is to be noted that each car has a durable and flexible sealing flap  18  attached to the front of the car and which is long enough to extend into the adjacent car and substantially seal the gap between the cars. The flap can be made of any suitable flexible material such as polyurethane, rubber, nylon, and the like.  
     [0059] The middle cars and the end car all have projections  24  on the lower front edge of the side drive plates  19  and  21 . It is preferred to use semi-circular projections but any suitable shape can be used. The front car and all the middle cars all have a corresponding openings  26  in their side drive plates. This enables the train to be flexible in the vertical and horizontal plane.  
     [0060] The trough  14  is firmly supported by a plurality of upper support brackets  23  and the lower brackets  22  in turn support these  
     [0061]FIG. 3, along with FIG. 4 shows the details of the front car and the remaining cars, respectively. The cars are mounted on wheels  20  with the front car having four wheels and the middle cars and the end car having two wheels. Each car has a series of cross braces  30  and support beams  36  as is shown in FIG. 3 and FIG. 4. The front car has two front wheels  20  mounted on an axle  25 . In addition, the front car has tapered side drive plates  17 , which are aligned with and similar to the parallel side drive plates  16 . The distance between the front of side drive plates  17  is less that the distance between the rear of the side drive plates  17 . Thus, they have a taper and can fit into the drive stations without shock. This makes it easy for the train to enter between the drive wheels  12  on each and  
     [0062] every drive station. The rear wheels of these cars are mounted on an axle  27  equipped with a threaded portion  42  and a locking nut  40 . These cars are coupled together by clevis pins in conjunction with the rear clevis bracket  32  and the front clevis bracket  34 .  
     [0063] The loading station for the car train is of a conventional design as shown in FIG. 18 of U.S. Pat. No. 3,752,334 and FIG. 6 of U.S. Pat. No. 3,332,535. FIG. 7 shows a dumping station for the car train. The train is pushed up the rail incline  2  to the double rail loop  38  supported by posts  44  with suitable footings such as concrete footing  46 . As the train inverts, it dumps its particulate cargo and it accumulates into a pile  50 . The transported cargo can then be transferred by standard equipment such as truck  48  for further operations or sold or stored.  
     [0064]FIG. 8 shows a typical cross sectional view of the train in an inverted position and it is taken on section A-A in FIG. 7. The weight of the now empty car is on the lower rails  2 . The empty train is then restored to an upright position by mechanism (not shown) and sent back to the loading station.  
     [0065]FIG. 9 shows the train going over an outside loops in the direction of the arrow (from left to right). The flexible flaps  18  discharge the cargo as the train approaches a vertical position. The projection  24  and the side plate openings are also illustrated.