Control Systems for Oil and Gasoline Electric Locomotives and Cars

A review is given of the development of self-propelled railway vehicles which utilize electrical transmission, paying particular attention to the ways and means of regulating the torque demand on the internal combustion engine which serves as the source of power, and the supply of power to the auxiliaries. Two general designs are discussed, and classified as ``differential field control´´ and ``torque control.´´ In differentiating between these two systems, two types of differential field control are outlined, giving their major advantages and limitations. The principle of torque control depending upon constant engine speed is discussed, enumerating its advantages over previous schemes. It permits the absorption of the entire engine output for any throttle opening and engine speed selected. The various relays and control devices necessary for proper operation of the scheme are described, together with the use of the auxiliary generator and main generator for compressor operation and battery charging. The appendixes deal with the design of auxiliary generators for differential field control and a short description of the method of limiting the torque required by means of a torque regulator and contactor. The problem of overcoming hunting of the system due to lagging of the field change and its solution are given. The differential field control comprises the minimum amount of apparatus consistent with operation of the car or locomotive and its auxiliaries.