aboard the vehicle for energizing the drive means of the vehicle." '864 patent at col. 1, lines 12-16.
7. Shuttle cars are within the inventor's field of endeavor.
8. During the prosecution of the patent application, Joy's prosecution attorneys advised the examiner that pertinent art may possibly reside in the field of power excavators. Amendment filed Dec. 28, 1976.
9. The Standard Handbook for Electrical Engineers shows that shovels, such as the P & H mine shovel, are power excavators.
10. During the reexamination, Joy stated that "electric locomotives and shuttle cars have existed side by side in coal mines since the inception of shuttle cars in the 1940's." Brief for Appellant dated July 8, 1987. Electric drives on both the locomotives and on shuttle cars operate in the same environment, and both are haulage vehicles.
11. The P & H shovel references and the electric locomotive references are reasonably pertinent to the control drive system problem faced by the inventor.
12. The P & H shovel references, the electric locomotive references, and the prior art shuttle cars are analogous art.
C. Content of the Prior Art
13. The Joy patent describes the advantages and disadvantages of AC and DC shuttle cars.
14. U.S. Patent No. 3,257,597 to Weiser recognized that AC traction motors were considerably more bulky and less efficient than DC motors. The reference recognizes that various attempts have been made in the electric locomotive field to convert AC input to DC output to combine the advantages of an AC power distribution system with a DC propulsion system.
15. U.S. Patent No. 2,549,405 recognizes that DC drive motors are advantageous because of their easily obtainable variable speed, but for long-distance trolley locomotives, AC is advantageous because of the ease with which voltages may be increased for power transmission and decreased for utilization.
16. The article by Barnes, Mining with a-c power, Mechanization, October 1960, sets forth many reasons for the trend toward AC mining from DC mining, including increased efficiency of power transmission.
17. The P & H shovel references relate to a surface mine loader. The shovel has a DC traction motor and a three phase AC power supply rectified in controllable amounts for application to the DC motor. The power conversion system includes a transformer with a three phase AC output. The AC is rectified to DC using thyristors, or silicon controlled rectifiers.
18. French Brevet d'Invention No. 1,152,782 (the French patent) relates to a fixed wheel rail vehicle. The locomotive has an AC-DC conversion system, in which a single phase AC power supply is converted in controllable amounts for application to a DC motor. The conversion system includes a transformer and rectifiers. The output of the conversion system is controlled by selecting different configurations of transformer windings.
19. U.S. Patent No. 2,434,585 to Renshaw shows an electric locomotive energized by either a trolley conductor or a cable reel.
20. U.S. Patent No. 1,123,602 to Sessions shows a coal mine locomotive with a cable reel.
21. U.S. Patent No. 2,599,061 to Lee shows a prior art shuttle car, which is powered through use of a cable reel.
22. The article by J. Oliver, et al., Electric Locomotives for the Muskingum Electric Railroad, IEEE Conference Record of 1968 Third Annual Meeting of the IEEE Industry and General Applications Group, Sept.-Oct. 1968, shows an AC-DC conversion system for use on an aboveground electric railroad. The article shows that the output from the conversion system transformer can be controlled in a step-by-step fashion using switches which select different secondary windings of the transformer.
D. Differences Between the Prior Art and the Claimed Invention
23. Prior art DC shuttle cars did not utilize the transmission of AC power through the trailing cable and did not convert AC to DC on the shuttle car.
24. Prior art AC shuttle cars did not convert AC to DC on the shuttle car and utilized AC traction motors rather than DC motors.
25. Prior art shuttle cars did not show the particular means for converting AC to DC in a step-by-step fashion as recited in independent claim 16.
26. Several prior art references show the conversion of single phase AC rather than three phase AC.
27. The P & H shovel and the electric locomotives are too large or dangerous to use in the environment of the shuttle car.
28. The shovel and the electric locomotives cannot be modified to operate as shuttle cars, and their electrical circuitries cannot be used on a shuttle car.
29. The P & H shovel is a huge aboveground loader, not a haulage vehicle.
30. Electric locomotives do not travel in random paths in an explosive underground environment.
E. Level of Ordinary Skill in the Art
31. The cited references reflect the appropriate level of ordinary skill in the art.
32. One of ordinary skill in the art to which the subject matter of the invention pertains would have knowledge of the operating conditions for shuttle cars.
Date: March 12, 1990
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