why train wheels AREN'T FLAT

why train wheels AREN'T FLAT train wheels might underrated engineering genius look closely they barely need anything to stay on the rails here's why the wheel surface isn't cylindrical it's that subtle taper creates a self- centering effect if the axle shifts sideways the diameter difference automatically pulls it center no sensors no motors just geometry now here's where it gets really clever unlike a car where each wheel spins independently train wheels are single axle they always rotate speed a train turn when it enters the whole axle shifts slightly toward the outer wheel the wider part on the narrower part bigger effective diameter on the outside means more distance covered per rotation even at the some RPM wheel naturally travels further than the inner one 0 slipping 0 differential no electronics no complex systems this solution is over 200 years old and still even the most advanced trains today pure shape doing that's what makes it timeless engineering