Direct-Current Motors for Coal and Ore Bridges

This paper gives a brief description of the mechanical arrangement of a coal bridge. The bridge consists essentially of a trolley car with hoisting mechanism for a self-filling bucket. A series-wound motor is recommended for driving the trolley car; and the proper method of gearing the motor for the most economical results is discussed. A series-wound motor is recommended for a low-speed hoist and a shunt-wound motor for a high-speed hoist. The relative merits of the two methods of winding the motor are considered.