The speed-time electrograph

The determination of speed-time curves and current-time curves as related to the duty cycles of electric railway motors may be greatly simplified by the use of an electrograph which has been developed, thereby making unnecessary the usual calculations which require considerable time. In this machine, the curves are drawn on an oscillograph screen. The equipment, which´ can also be used to obtain other characteristics, depends for its operation upon the similarity of equations in the mechanics of train movement and those involved in the electrograph circuit.