How do you decide the diameter of the rotor in a disc brake trains (LRT and MRT)?

[fadlianturu5]

Hello, I have a project to calculate and design a rotor disc for LRT and MRT trains. I've tried to find papers about this, but all I've found are calculations related to heat transfer when the brakes are applied. When I look at the UIC (International Union of Railways) standards, it seems that they provide a fixed design and material that can be manufactured. How do you exactly calculate the rotor disc with factors such as braking torque and weight? And how does the diameter of the rotor come into play?

 

[MintJulep]

You won't find any public papers. There are a small number of companies that design and manufacture train brakes, and they all consider this to be their proprietary super-secret sauce.

At any rate, it's all about heat.

The mass of the train plus the rotating inertia of the wheels, brake discs, motors and gears defines the linear force needed to achieve the desired deceleration rate.

The radius of the disc and the radius of the wheels defines the torque required.

The design braking profile defines the energy balance for heating and cooling.

Try the smallest number of the biggest discs that fit in the available space and run some thermal simulations. Repeat until you find a combination of disc size and number of discs that don't overheat.

 

[BrianPetersen]

Calculating the kinetic energy that has to be dissipated as heat is the easy part. Estimating the rate at which this heat is radiated or transferred to surrounding air is the tough part.

The actuation forces (fluid pressures) required on your train car have to be matched to what's happening in the rest of the system, too. If the train has your train car plus those built by others in it, you can't have your wheels lock up and slide before anyone else's engage, or vice versa, and it has to work with what's coming from the locomotive. If the train has interchangeable bogies, they all have to work the same. This is why there are fixed designs...

 

[IRstuff]

Seems like you could find a railroad museum and look at the brakes directly

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