Abstract
In-wheel motor is one of the methods to increase the driving efficiency. And direct drive can realize the highest mechanical efficiency because of its simple structure. Direct drive has no gears between the motors and the wheels. Therefore the parts that have mechanical loss are the bearing and the seals. The frictions of the parts are tested and the new method of parts layout is also suggested. The friction of the direct drive motors is 30.4N with the tires whose radius is 0.3 meters. And electric consumption of the friction is 8.94 Wh / km in JC08 mode.
