Selection of Equipment for Multiple-Unit Cars

Electric multiple-unit cars afford the most economical method of handling suburban passenger service, provided the volume of traffic warrants the high initial expense of electrification. Nevertheless, because of the low use factor of these cars in commuter traffic, fixed charges are a high percentage of the total cost of the service. It is important to reduce these fixed charges by finding means for lowering the initial cost of multiple-unit car equipment. It also is important to simplify such equipment in order to minimize maintenance costs. One method which has proved to be effective in reducing costs in many other fields is that of standardization. The development of rectifier-type motive power for application on high-voltage a-c systems gives promise of effecting a degree of standardization for the majority of applications by the wider use of low-voltage d-c traction equipment. Further economies should be possible by careful selection of available alternatives in details of the equipment. Various choices are discussed with particular reference to low cost and low maintenance.