Material or article handling – Load-transporting type vehicle and external means... – Involving movement of load by gravity from wheeled vehicle
Reexamination Certificate
2002-11-12
2004-12-28
Bidwell, James R. (Department: 3651)
Material or article handling
Load-transporting type vehicle and external means...
Involving movement of load by gravity from wheeled vehicle
C414S384000, C105S241100
Reexamination Certificate
active
06835041
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a system for transporting bulk materials via a railway and for discharging the bulk materials at an unloading site, and more particularly to a railroad car and container for transporting bulk materials and a system for discharging the materials from the container.
BACKGROUND OF THE INVENTION
At present, the only remaining viable mining industries in the United States are the coal and aggregate industries, accounting for 45 percent and 40 percent of US mines, respectively. The coal industry produces about 1.2 billion tons/year, of which about 75 per cent is shipped to market via railways. Coal sells for about $5/ton FOB at the mine in the western United States and about $20/ton in the eastern United States. However, delivered costs have been reported at about $15-$30/ton, with the western railroads receiving $0.012-$0.016/ton mile freight rates. In comparison, the aggregate industry produces about 3 billion tons/year, of which only about 6 percent is shipped to market via railways. Aggregate sells at a mine for the same average price as Wyoming coal, around $5/ton. The aggregate products are typically shipped 25-200 miles to market at $0.08-$0.14/ton mile or $2-$28/ton by trucking. Average western United States railroad non-coal mineral freight rates of around $0.0258/ton mile have been reported. Thus, delivery of aggregate via railways could compare quite favorably with delivery by truck.
These statistics suggest that the railroads are servicing the coal industry far more effectively than the aggregate industry. Indeed, the railroad industry has shown limited interest in the aggregate industry due to a perception that transporting aggregate would be less profitable than transporting coal because aggregate is shipped for shorter distances and has a lower delivered price than coal. As a result, railroads charge higher aggregate freight rates, and aggregate shippers are uncertain as to how to use railroads effectively.
In particular, the lack of an efficient railroad car for transporting aggregate and the lack of an efficient way to unload or discharge aggregate from existing cars are considered to be major deterrents to the increased use of railroads for shipping aggregate. At present, the average turnaround time for railroad cars known in the art is about 21 days. However, a viable large volume viable commercial system transporting materials over distances up to about 200 miles would need to have turnaround times of one to three days Although 1-3 day turnaround times are achievable with some existing equipment, such short times have been achieved only for limited size material and with large capital equipment and operating costs.
In one fast and effective system for transporting and dumping coal, the coal is shipped in car unit trains pulled by several high horse power locomotives. These trains may include 100 or more railroad cars, with each car carrying about 100-115 tons. Commonly, aluminum rotary dump cars are used. These cars are equipped with special swiveling couplers and are unloaded by being turned upside down. The unloading facilities used with these cars include rotary dumps that engage the car and track to rotate them on an axis through the couplers. Typically, large concrete silos are used to load such trains. The locomotives cost over $1.5 million each, the rotary dump cars cost over $50,000 each, and the construction costs for the rotary dumps and loading silos are several millions of dollars.
However, rotary dump systems such as those used for coal are much too costly for aggregate applications. Further, most existing cars designed for hauling coal are not suitable for hauling aggregate due to the significantly greater density of aggregate, approximately twice the density of coal Crushed coal has a density between about 40 and about 54 pounds/cubic foot, while crushed rock has a density of between about 94 and 100 pounds/cubic foot.
A variety of systems and types of railroad cars have been used for transporting bulk materials such as aggregate. The predominant type of car is an open top bottom dump hopper car, constructed of steel. Because these cars are emptied by dumping from the bottom, expensive permanent facilities are required beneath the railroad tracks to receive the dumped bulk materials. Typically, these facilities include large, rail-supporting I beams suspended over permanent steel hoppers, all of which are mounted in thick, high-strength concrete foundations about 16-32 feet beneath the railroad tracks. Once built, such facilities are never moved unless closed down, and then only the hopper can be salvaged. The concrete foundation must be abandoned or destroyed. Further, unloading smaller sized or wet bulk materials, which pack during transport, generally requires a device that vibrates the cars to dislodge and discharge the loads.
Numerous car designs have been proposed with different car lengths, different numbers of hopper doors, and using different types of doors in attempts to improve discharge rates and provide a system more compatible with using railroads instead of trucks for transport. One of the current predominant business strategies is to alter old steel cars designed for transporting coal by cutting a section out of the middle of the car to reduce the maximum cargo volume, along with decreasing the number of doors and making the slopes of the floor sheets steeper at the ends of the cars. These car modifications increase dumping efficiencies and train capacity by reducing the number of doors handled by employees, allowing rock to dump faster due to the steeper angles of the floor sheets at the ends, and creating shorter cars that fit on shorter sidings.
However, the hopper doors on existing cars generally do not accommodate material larger than about six inches in diameter, and often the maximum acceptable product diameter is less than three to four inches. These cars cannot handle many aggregate industry products that have larger particle sizes, including some items, such as rip rap and decorative rock with diameters as large as two to four feet.
Other systems have been proposed and used to transport and dump aggregate materials. For example, the Car Topper-Herzog method uses a patented loader that sits on top of the sides of a gondola type car and digs material out of the car. The Difco type car and variations have a hinged body built into the car. An air or hydraulic ram system, incorporated into the car, is used to tilt the car body on the hinge for unloading to either side. In the slot or trough train, specialty gondola cars have doors at either end of each car in the train and are designed to allow a loader to drive through each car and on to the next car, digging out the material from the car floor and dumping the load along the side of the car. The dump train, developed by Georgetown Railroad, includes 16-18 open top hopper cars with a belt running through the cars to the end of the train, conveying material through the train cars to a special discharge car with a 50-foot conveyor boom to discharge anywhere on either side of the end of the train. In other applications, a belt is placed above the rail and beneath the car's door to transport dumped material away from the car and tracks.
Other major bulk materials shipped by rail include iron ore and garbage. Iron ore is usually unloaded in a manner similar to that of the first method, with dumping from open top bottom-dumping cars. Dumping occurs from a unit train onto huge piers extending out into the Great Lakes with large chutes directed into the holds of large lake vessels. However, due to the high density of the ore, 165 pounds per cubic foot, much smaller cars are required, and these cars have insufficient cubic foot capacity for practical use in transporting lower density bulk materials. At present, rail transport is used on a limited basis for garbage in ISO sized containers and specially modified box cars. The ISO sized containers, loaded with garbage, are delivered to a rail yard by truck, transported
Bidwell James R.
Bulk Unloading BA, LLC
Furst Marian J.
LandOfFree
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