I am trying to write a program that simulates the physics of a locomotive (diesel, not steam). I already have a method to get the tractive effort of the locomotive. If anyone must know, the one I am using in this example is the EMD F7-A.
I am trying to model wheel slip and all the forces that play into it. I already know I can use the adhesion factor (30% I believe in this case) to find the wheel adhesion. For an F7, it is 69,000lbs. Since the wheels can grip no more than 69,000lbs, how do I account for all the forces that may add up to 69,000lbs? I know that if the rolling resistance of the whole train adds up to over 69,000lbs the wheels slip, but what about other things?
The thing I am having the most trouble with is locking up the brakes. It's like a car, but on a larger scale. If I lock up the brakes on the train, chances are the locomotive is going skid. But what force is this? I am guessing it has something to do with kinetic energy, but since that's in Joules, how do I get the force?
Any and all help is appreciated. And feel free to correct me if I got any concepts wrong, I am kind of new at this.