:question:I probably did not say this proper but when I see a large train (consist?) sometimes miles long there has to be a huge tug of war between the last car and the power unit, I watched a video of some train in the PA coal area and it made a very large turn coming up the hill you would think that the law of force would want to straighten the whole works out. Hope I said this right and I do hope I posted in the proper area.:question:
Don't think for a second, those freight trains don't want to straighten those curves out. Trains have been known to leave the tracks on a curve, which is known as string lining. One of the reasons the 1X1 foot scale engineers super elevate the outside track. Railroads learned to build wider curves going from 10 degree turns to 6 and 4 degree curves. Good question and I hope my answer helps.
The sub-roadbed is properly constructed and maintained to uphold the train weight, superelevation and track speeds well calculated. Good old fashioned gravity....
I appreciate the reply and now I know how it works now this begs another question in this model RR hobby do you elevate the track.
There us so, so much more to the physics of train movement and handling in curves in particular. With a train of 100 cars, there are 100 different forces happening at once. Acceleration, decceleration, up hill, down hill, helpers pushing, helpers in dynamic, mid train helpers, location of empty vs loaded cars on the train, etc. If a 100 car loaded coal train is charging a grade in Run 8 at 15 MPH and enters a curve, the cars will be pulling in opposite direction and trying to straight line the train. Sheer weight keeps cars upright. If a 100 car loaded coal train is gliding down grade with retainers applied and all units in dynamic braking, the cars will push against the locomotives and will try to push to the outside of the curve. Helper units in dynamics, when properly working will pull back from rear and dome cars wont push outside rail quite as hard.... on the other hand, too much braking from the rear can force cars to straight line. Sent from my LG-P930 using Tapatalk 2
There's another condition to consider. Each car's trailing coupler is pulling on the following car's leading coupler at a very small angle. That pulling force angle on the following car can be countered by that car's wheel flanges against the rail. When looked at on a car by car basis, there is little tendency for an entire train to string line. However, as said before, string lining will occur when the train's end forces try to counter each other, for instance when the engines in front are pulling hard, and the engines in the rear (pushers) are braking. The result is not pretty.
the easiest way is to use some styrene to super-elevate the curves, two degrees should be good, after all, this is a train, not a race car
This all came about due to RFD TV and the train videos and also a train I saw in 1986 off I-94 East of Dickenson, this train was hauling some kind of pipe that was welded into a very, very, very long length had to be close to a mile or more in length and I remember the pipe being white. I had wondered at that time how the hoot that it could pull. Around that same time I was in Minot ND at the SOO Line yard /Dispatch shack picking up all of their old teletype machines and delivering new IBM Computers, the engineer told me to put my truck on a flat and he would take me up to the next station where I had to pick up and deliver which was Portal ND. I said no thanks (would have been cool) see you there if you are fast enough and I had just shut the doors on the wagon and getting ready to head home when the train pulled in.
