Bullet Train-Engineering Connections

Shinkansen = Japan's Bullet Train.
Metal under tension. Begging you to Touch and Go ////
The world's first high speed railway. Still most technologically advanced in the world.



Mountain Fuji with Bullet Train.





円錐踏面.輪軸の構造と車輪の踏面勾配.
Railways wheels sit on the rails without guidance except for the shape of the tire in relation to the rail head. The flanges should not touch the rails. The flanges are the device that prevent the wheels becoming derailed.They're safety features.

This is exaggerated, but it is like the real train wheel. Conical shape.
Why aren't the wheels flat ?? Because the train needed get round a corner. The wheels need the flange on them to keep the train in the track.

Real train wheels.
See the following pictures show how it works.

The shape and location of the wheels and rails on straight track. Flanges are the metal lips that sit down the side of the track. We could put the flange on the wheels, but the trouble is the wheels would be guided around the corner purely on these flanges and they will wear them out.
Wear the side of the rails out and  it'll all be wrecked very quickly.

The location of the wheels in relation to the rails on curved track. The inner wheel uses the outer edge of its tire to reduce its travelled distance during the passage around the corner. The flange of the outer wheel will touch the movement of the train round the curved rail is not in exactly symmetry with the geometry of the track.

Conical wheels test. A cone rolling on its side turns in a circle and the train wheels use the same principle.

As it goes round a bend, the train is thrown out. the outside wheels effectively get bigger.
But the conical wheel can effectively change the size, they can make the trains unstable
even on the straight track that will cause the Hunting Oscillation.
In a conclusion:
If the train wheel is "conical", it can turn easily on the corner, but easily Hunting Oscillation.
If the train wheel is "flat", it can turn difficultly on the corner, but slightly Hunting Oscillation.
How can engineers come up with the solution to make the train wheels turn easily and reduce
Hunting Oscillation ??

Conventional Train Wheel

There will be optimum amount of slope -Cone-. Very high speed trains have very low amounts of cone angle. The angle is half as conventional train wheel.

Each wheel is precision machined to the perfect angle.



 For those speeds,the engineers can't just rely on the flatten wheels to avoid hunting oscillation.

Coiled springs absorb the energy of the hunting oscillation.





Pantograph.

high amps, big currents overloaded the thin wire.





If you have very very high currents, you need to use very big piece of metal to let the current flow.
The other way to give the train the juice it needs was the high voltage. Train lines usually carry 1500 to 3000 voltages. But the bullet train is near 25,000 thousands voltages. Such gigantic voltages, any break in the circuit between the wire and the pantograph can be catastrophic.



The whole thing is the compensatory mechanism and the result is the constant pressure against the wire. keep the high-voltage power supplied without frying the pantographs.

In 1899, Ferdinand Porsche designed the pioneering car in which each wheel was driven by a separate motor. The first four-wheel drive. With more driven wheels, you get better traction.

Conventional trains use the locomotives to pull or push the other carriages along.
Bullet trains use the Multiple Unit System.
4WD : Car = Multiple Unit System : Bullet Train 

As you can see Valentino Rossi "Hanging-Off" going round the corner. Cornering too fast is the problem for any vehicles. Newton Laws of Inertial and Centrifugal Force. Leaning is the technique going round the corner. The more the lean, the less the force pushing outwards on sidecars.


Bicycle and Motorcycle Dynamics. From Wikipedia.
I excerpted the passage of "Leaning" that is useful for me to understand the principle.
Unlike the wheels, bikes must lean during the turn to balance the relevant forces.
Gravitational, Inertial, Friction, Ground Support.
From above equations, which can calculate the Angle of Lean.
Where " v " is the forward speed, " r " is the radius of the turn and "g" is the acceleration of
gravity.



The same principle used on the bullet train. To make trains lean, tracks are banked, inclined into the bend.

[Highlights]
Hunting Oscillation
Pantograph
Multiple Unit System

[Questions]