id	keyword
ap-8606	wheels
ap-8606	resistance
ap-8606	energy
ap-8606	movement
ap-8606	tram
ap-8606	rail
ap-8606	vehicle
ap-8606	contact
ap-8606	bogie
ap-8606	railway
ap-8606	design
ap-8606	running
ap-8606	track
ap-8606	n·kn−1
ap-8606	gear
ap-8606	transport