The maximum speed from the purely technical standpoint of a railcar running is determined by the magnitude of the three acceleration factors: running resistance, motor driving force, and adhesion force. What is adhesion, and what is the relationship between running resistance and motor driving force that determines the maximum speed? We also calculate the maximum speed that can be achieved under various conditions. In addition, the latest technology for reducing running resistance and increasing adhesion force, and the mechanism of the VVVF inverter, which plays a key role in control technology for increasing driving force on slippery steel wheels and rails, will be explained. This book is also full of ‘information that is hard to find elsewhere’ such as why the adhesion force decreases when increasing the speed in the rain, what is the differences between automobiles and railways in the generating mechanism of running resistance, and why the traction motor was changed from direct current to alternating current.