Marathon Letourneau Company

Gary L Nelson

Ronald A Johnston

Dwight Baker

An improved method and apparatus for powering and controlling the operation of large diesel-electric off-road haulers of the type in which hauler drive wheels are propelled and retarded by DC electric wheel motors powered from on-board generators, optionally supplemented by DC power, from external trolley lines. In the disclosed system, thyristor-type converters connected into the system AC power grid are used to receive supplemental external power from DC trolley lines and supply it into the AC power distribution grid in the propel mode. The use of such thyristor-type converters makes possible the use of supplemental trolley line power without provision of separate switching or control gear to operate the DC wheel motors when trolley line power is received. Thyristor-type converters also may be used to supply current generated by wheel motors in the retarding mode to retarding resistors, making possible the use of the initial electrical power generated by the wheel motors to replace load requirements of the diesel engine, resulting in substantial fuel savings.

Method for propelling and retarding off-road haulers

An improved method and apparatus for powering and controlling the operation of large diesel-electric off-road haulers of the type in which hauler drive wheels are propelled and retarded by DC electric wheel motors powered from on-board generators, optionally supplemented by DC power, from external trolley lines. In the disclosed system, thyristor-type converters connected into the system AC power grid are used to receive supplemental external power from DC trolley lines and supply it into the AC power distribution grid in the propel mode. The use of such thyristor-type converters makes possible the use of supplement trolley line power without provision of separate switching or control gear to operate the DC wheel motors when trolley line power is received. Thyristor-type converters also may be used to supply current generated by wheel motors in the retarding mode to retarding resistors, making possible the use of the initial electrical power generated by the wheel motors to replace load requirements of the diesel engine, resulting in substantial fuel savings.

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Longview, TX, United States of America

Gary L Nelson