Progress in Development of Trolley-Coach Overhead Reflected in Higher Service Standards

The expansion of trolley coach operation to include 50 transit systems in the United States and Canada has been greatly helped by the progress made in the development of overhead distribution materials. Beginning with the installation of the first transit-type trolley coaches in Salt Lake City in 1928, the inadequacy and limitations of the earlier designs of equipment were recognized. Since 1928 it has been necessary to add many new devices and redesign many old devices to provide better reliability and permit of greater flexibility of operation. The development of trolley-coach overhead materials has been concentrated mainly on 1. Current collection 2. Hangers and insulation 3. Curve materials 4. Turnouts and crossovers The improved current collection equipment incorporating the carbon-insert shoe has been responsible for the reduction of wear on fittings and trolley wire. The carbon-insert shoe has also been responsible for the complete elimination of trolley-wire lubrication formerly required for the all-metallic shoe collector. Improvements in insulated hangers have resulted in a more dependable distribution system and have been responsible for the elimination of considerable secondary insulation formerly inserted in the supporting span wire between positive and negative trolley wires.