Would distributed power make any difference in Trainz?

W

whyfly2

New member
There was an interesting item in Trains magazine, www.trainsmag.com, (last year, I think) describing how distributing locos throughout a long train results in better performance around turns than having all the power up front because it reduces friction between the flange of the wheel inside the turn and the outside edge of the inside rail. I don't remember in which issue it appeared. You might find that issue in a library.

Has anyone tried this in Trainz and, if so, how did it turn out?

Art
 
You can certainly run mid-train and rear-of-train 'DPU' units in Trainz, but it makes no practical difference to having all head-end power. I guess it would take some fairly subtle scripting or programing changes to make it work 'properly'.

I have played around with rear-end dpu a bit and found that while it looks good it seems to muck up ATLS triggers, specially if a train is reversed so that what the sim thinks of as the 'back' is now the 'front'. Other than that though, its all good.....
 
In my humble opinion, DPU other than looking good for videos/screenshots/etc, serves no real purpose as Dermmy has eloquently put it. Trainz lacks real world physics with correct loco weights, carriage weights, etc etc etc (and the computing grunt to keep track/manage it all on the fly would be insurmountable I suspect) - so other than looking good for certain things, there's no real purpose to it, put them at the front, middle or back (push/pul configuration), it really doesn't matter.
 
Muliebuck said:
In my humble opinion, DPU other than looking good for videos/screenshots/etc, serves no real purpose as Dermmy has eloquently put it. Trainz lacks real world physics with correct loco weights, carriage weights, etc etc etc (and the computing grunt to keep track/manage it all on the fly would be insurmountable I suspect) - so other than looking good for certain things, there's no real purpose to it, put them at the front, middle or back (push/pul configuration), it really doesn't matter.
Click to expand...
But it does serve a more realistic operation. Railroads like UP and BNSF uses Mid and rear train DPU's all the time, even sometimes 2 or 3 of them at a time.. In real life, it does serve a purpose as the OP mentioned above. I have tried and it did not make a difference. However, I like doing it anyway, becuz it makes me feel like I am operating a train like UP would. Do it how you like it and have fun!

Chris/Enzo1
 
That's a shame, because I thought that would help relieve stress on the couplers... Oh well.

Having just run it, I know JR has a mid DPU in one of the consists in Walong Stall (Mojave Sub Route) - and that uses ATLS crossings and seems to work ok.
 
Just to clarify - I didn't say "DPU Breaks ATLS", I have had one issue on one crossing which played up when a reversed DPU consist ran over it. So did my testers. The crossing was fine when the DPU train ran over it 'forwards', but after unloading and reversing the DPU train that one crossing did play up. I tried very hard to work out why the crossing went wonky but couldn't, and the crossing is not wonky with any other train. It's always wonky with a 'reversed' DPU. Could be the DPU, could also be the weather next Friday!

It's a shame, because I really wanted to run DPU on that train in a released session but I can live with uncoupling the head-end power and running the locos to the other end. The crossing is fine that way even though the consist is still running 'backwards'.......
 
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@ Dermmy - Would it be any use to clone the rear loco and turn it into a non-powered vehicle? Problems with asset ownership spring to mind.

I agree that the physics model for Trainz is far from complete. One thing I have noticed is that when a train starts off in a rearward direction the wagons "spread out" when the train picks up a bit of speed. This is not unrealistic when the track is level but if it is rising then this goes against the laws of gravity.

When the train is then stopped the wagons do not close up immediately, but when the loco is started again (still in a rearward direction) the wagons then close up and it appears as if the rear of the train is travelling forwards.

Interesting but not a train-smash.

Trevor
 
Dermmy said:
Just to clarify - I didn't say "DPU Breaks ATLS", I have had one issue on one crossing which played up when a reversed DPU consist ran over it. So did my testers. The crossing was fine when the DPU train ran over it 'forwards', but after unloading and reversing the DPU train that one crossing did play up. I tried very hard to work out why the crossing went wonky but couldn't, and the crossing is not wonky with any other train. It's always wonky with a 'reversed' DPU. Could be the DPU, could also be the weather next Friday!

It's a shame, because I really wanted to run DPU on that train in a released session but I can live with uncoupling the head-end power and running the locos to the other end. The crossing is fine that way even though the consist is still running 'backwards'.......
Click to expand...

Hi Dermmy,

I know of no reason why what you are seeing should happen. The ATLS Triggers don't look at individual vehicles, they just see the whole train a single lump. So long as the train has cleared the final Trigger in the sequence before you 'reverse', ATLS will forget that train.... and see it as a new one when you return. ATLS Triggers are non-directional so they will get confused if you change the train direction while still within an ATLS sequence. It shouldn't matter how the train is made up though.

I have recently discovered a bug that caused Triggers to work incorrectly if you set them up by only typing in a 'save to map' code and not first clicking on the set-up icons. But that again would not [FONT=&quot]differentiate between consists[/FONT]. (Updated ATLS assets now on the DLS).

Try the update, but if you still get the problem, send me a cdp of the route and I'll take a look.

Boat
 
Thanks Boat, I have an updated Beta out in the next couple of days, I will shoot you a link...

Andy :)
 
With correctly configured rolling stock and locomotives (accurate custom enginespec assets, or at least 'generic' custom enginespecs for different designs/sizes of wagon), and the vehicle physics rule added to the session, DPU may actually provide an advantage, as it should help reduce coupler stress (note, the current version of TS12 has a bug that will cause issues with this - TS2010 at the moment would be a suitable location to test this).

You may also find brakes will release quicker (Trainz, from memory, does take the train length and number of locomotives into account when the brakes are applied/released).

That said, there will be limitations on how realistic this is. Not really done much with it myself, so I can't be too sure just how much of a difference it would make :)

Regards
 
Trev99's comment that a loco can be used as a non-powered vehicle made me wonder if a loco's not being at the head end would keep it from operating. I set up a long freight train in TRS2006 consisting of two SD40s, one 1500-ton freight, one SD40, one 1500-ton freight, one SD40, and one 1500-ton freight.

Operating the train with the DCC knob on a straight track, it took 1:03 minutes from full throttle to 78 mph. Without the two distributed SD40s (just two SD40s up front), it took 1:30 minutes to 78 mph.

The next step would be to create a lyaout with a long curve, and try some tests of power/time/speed, first with the distributed locos, then all four up front to see if there's a difference.

Art
 
It won't make any difference where you have the locos as long as it's the same number of them, the acceleration will be the same.
Where it might make any odds is if the vehicle physics rule is being used. ( I knew I'd read that before, Zecs post).
 
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