Why does a Train derail speed or physics?

[LionelDave]

I've been wonder about this for a while.

Does a train derail because it is going around a curve too far over the speed limit or does it derail because because the game's physics tell it to derail.

For an extreme example: if a train has a speed limit of 10 mph around a curve you go 50 mph around the curve it derails. But if you set the speed for the curve to 60 mph with out changing anything else will the train derail going the same 50 mph?

It's a slow day at work.

Dave

[Machinist]

Dave, both factors count, and there is also a 3rd one: a tilting factor (forgot the blueprint name), set for each engine differently (not sure about vehicles in general).

Depending of vehicle there's a tolerance to overspeed beyond the track limit, may be 20%, 50%, 100% or whatever (tilting factor dependent). If you set the rule of track raising the speed limit, there will be a proportional new upper limit to run before derail, and vice-versa.

Doc.

[dieseldown]

Good ex: I'm driving 130 cars loaded with coal on my way to Barstow. The speed limit is 79 in the area and I'm driving at 64 mph. About 20 miles out there's a left hander and the rear of the train tilted. EOJ
Live & learn,
Paul

[LionelDave]

Thanks for the information because I was thinking about trying to raise some speed limits but will not try it now because of the tilting factor.

Dave

[Machinist]

Thanks for the information because I was thinking about trying to raise some speed limits but will not try it now because of the tilting factor.

Dave

You misunderstood what I said. The tilting factor is (say) a percentage of track speed limit. Let's suppose it's 50%: you'll derail in a track of 10mph when you reach 16mph. If you raise the speed limit to 60mph (of same piece of track) you will derail only if you reach 91mph. I have a lot of scenarios in which I raised the track speed limit from 30mph (train derailling at 50mph or so) to 60mph for test purposes, and trains ran fine at 80mph, that's not a problem.

In other hand you can run at 50mph in a 60mph track, but if you lower the speed to 10mph you'll derail over 15mph with the same train in the same section of track.

Cheers,
Doc.

[Kali]

The "chanceofderailment" blueprint setting or whatever it is adjusts the centre of gravity - higher it is ( more +ve number ) and the easier it'll tilt outwards. The other things that affect derailment are mostly coupler-related, from experience.

Try setting chanceofderailment to negative numbers one day, very strange...

[GaryG]

One other item that can cause derailments is poor physics as well as improper train handling, especially when braking.

Visualize going downgrade with dynamics only and no train brakes applied. You go around a curve and for some reason it derails mid-train. A probable cause, many locos have DB physics that apply far too much force. With so much of the train running without braking, excessive forces that work "ok" on straight track cause the cars in the curve to be pushed to their limits and either tip over or jump off the rails. That problem along with trainbrakes that apply excessive force invites trying to run with DB's only, leading to these types of derailments.

My humble opinion, of course ;-)

GaryG

[dieseldown]

Another thing I've learned is never mix F7 type diesels with coal cars. The F7 will out brake the coal cars leading to what I call the 'Squash effect', that's a new railroad term I think or not.
Paul

[Kali]

I'm convinced now the dynamic brakeforce in the blueprints should be in k-lbf, usually ( because it's what the docs say! ) it's put in in kN, which is about 5x as big as it should be. That's not going to help braking when your train has stupidly squishy couplers either...

So for instance a SD40-2's db MaxForce should be 60 ( thousand lbf ); convert that to kN and you get 266 or so which is what it used to be - the RW3 one actually has 60 in the blueprint. However lets go look at the HSC F7; MaxForce 267! no wonder it jackknifes trains, that would be 1190kN. ( To put it in perspective, a SD70ACe which is probably one of the best load luggers in the world at the moment can manage 470kN braking effort in total, and starting effort which is where an AC unit shines because of their startling adhesion, is 870kN ). Oddly the default F7 in the Kuju folder has 60! too high for a F7 really but at least it's in the right units.

To put it another way; if you ran your 1100 tonne train into the stopblocks at ~2mph & stopped in a metre, you'd have the same brake force as a single HSC F7.

[LionelDave]

Sorry I couldn't get back to you earlier (bad week end for using railworks for me)

Thanks for all the answers espically Doc.. your right I didn't understand what you were saying at first but you second comment cleared things up for me.

Dave

[TrainMaster1]

A train derails for many reasons. Excess speed, mechanical failure and a little thing called string lining or train lining where the cars desire is to continue straight rather than bend around the curve.

Also I saw in here hat someone said the speed limit on Cajon I believe is 79. That is only for passenger train only. A 130 car coal train would have a 45 mph restriction just for TOB (Tons over Operable Brakes rating). Very little coal moves over this route save for some UP run through moves currently because of the grades involved.

Knowing your grades, degrees over curvature, TOB ratings are just a few of the many elements you need to know in order to make it home safely. Power braking and learning how to set a minimum reduction will help you down the hill safely. This is doable in RW if you are willing to fix the engine files in the first place.

Nick