Once more - Train physics

[Toripony]

Since the challenge of driving the Alleghany sub is all about grades and control, I have a great interest in accurate physics. So, I didn't hesitate to go do my own testing based on this post since my experience differs with the OP, Mr Murphy's, findings. I laid 12 tracks at 5% grade and "loaded" each at the top end with a different model Player locomotive of US, German, and UK origin positioned to roll backwards down this steep grade. Every cab I entered began rolling backwards immediately upon entering. For some, the "startup" 70% brake halted the rolling, but not all. Releasing the brake (or centering the throttle in a couple of cases) let every one of them roll freely. This concurs with all my previous experience, though I admit, I rarely drive one single engine.

Just for fun, I reapplied train brakes at 100% just to see if the loco would slow down; alarmingly, the SD40-2 did NOT! It was truly unstoppable after attaining 10 mph!

[Kali]

Just for fun, I reapplied train brakes at 100% just to see if the loco would slow down; alarmingly, the SD40-2 did NOT! It was truly unstoppable after attaining 10 mph!

:o er remind me to look at that, lol. There is a RWTools setting to fix US engine brakes I noticed, I don't know what it does. If someone could provide me with any info about US automatic airbrakes ( standard pressures and so on ) I will go and have a look at the default stock. I'm sure there must be some standards body over there.

I am wondering if it was the blueprint type ( I guess he used all electrics? ) or perhaps just the stock he used that made them stick. I will repeat my tests with some different stuff sometime.

[kevarc]

I used Cajon and used the default US stuff and everything rolled - it did not matter what direction the unit faced or position of the reverser.

[Toripony]

I can't say exactly what the brake modd tool in RWTools does, but I like what it does. I think it only affects train brakes which it makes much more controllable as well as slows the recharge just a tad. I can now apply 3 or 6 lbs of train brake without having to play around with the brake pressure. This is from Mike Simpson's readme, though I think it contains some quoted information (I think Rich wrote the modd and Mike integrated it into RWTools):

v2.2.36
New option on Edit Assets at Edit rolling stock\Change US diesel airbrake settings - This includes the work done by Rich S. on trainsim.com and allows you to select any US diesel and update the brake settings as perhis text below. Make sure you copy the files in the Templates folder into your RW_Tools\Templates folder.
"When I first received Rail Works I found on the North American Diesels the automatic (train brake) was not making a minimum reduction until you moved the handle about 30% of it total movement. On the prototype you move the automatic brake handle about 8% to get a minimum reduction (about 7 lbs. reduction in the brake pipe) The full service zone then runs from that 8% to approx. 50%. At Full service (approx. 50% handle movement) you’ll get approx. a 25 lbs. reduction on the brake pipe. The next zone on the brake handle is the suppression zone at about 51% to 60%. This zone lowers the brake pipe even further and is often used to reset penalty brake applications. The next zone on the automatic brake handle actually has a couple of different names (continuous service or handle off) depending on the railroad. Kuju and RSC used the continuous service designation and this zone is approx. 65% of the handle movement. The Continuous service or Handle off is only used when the engine is being operating in the trailing position. The last zone on the automatic brake valve is the emergency position and I left this value set at Kuju / RSC position of 95% handle movement. These setting are good for any North American Diesel Locomotive (ALCO, EMD, GE) with the type 26L air brake handle and / or newer air brake systems like the 30 and 32 air from NYAB and Wabtec. I’m not 100% positive but I believe all locomotives built after 1968 had the 26L brake system. Most first generation diesel locomotives were equipped with 6 and 6L air but as these units were rebuilt their brake systems were replaced with the newer air brake equipment. The next brake system was the 24 air that came on the GP / SD 35 locomotives. But like the first generation units, during rebuilds these engines were also upgraded to the newer 26L air brake systems. So I guess you could use these settings for all North American diesels."

[Kali]

Ah, that just tweaks the brake control then; yeah we've had to do the same thing with UK stock also, much of which was set up with Kuju-US brakes. We only have off-variable state of on-full though, basically.

We have the RSSB to set standards over here - some of you might be interested in their document repository which has almost everything to do with operating and managing the railways here, including the rulebook and if you also check withdrawn documents too, there are some going back to the 1960s. I would really like to find something similar for the US, if such a thing exists - someone has to set *some* standards for compatibility.

[MrMurphy]

Sorry guys but there was a mistake in mesurement unit conversion. The track was German mainline one and F4 Hud makes a mistake showing 5% as grade value - the true value has to be 0.5%. So it's calculation error in RW. As much as I know for US routes F4 dispays right value. So the German track gradient seems to be the only one which gets faulty value in F4 Hud. Yeah 0.5 or 5% it's quite different but still do not answer to my question - why German BR-101 loco was moving only if faced to downhill and not when faced to uphill. There has to be some kind of mistake in core code anyway. And is it really true that 6 axle locomotive do not roll back on 0.5% grade? Seems very unrealistic but I have to make some calculations.

[MrMurphy]

Sorry guys but there was a mistake in mesurement unit conversion.

Because it was German track the measurement unit was "promille". 1 promille equals to 0.1 persent. So my test was made on 0.5% gradient instead of 5%.

[Chacal]

♫Cause nothing really ever goes the way it's been
Yeah she's in Ohio and I'm on some back road♫
♫Driving to the city and then who knows

Cause that's how she rolls

♫I wish that I could turn this car around
But she's got a boyfriend now♫
(Whoa)
(Whoa)

[Kali]

http://forums.uktrainsim.com/viewtopic. ... 1&t=118158 - he was right, there actually is a problem. Given the results get wierder the longer the train gets, not so hot for US-sized consists. I'm not going to make much of a fuss until we know if it's different in 18 days, but if it hasn't been changed then a lot of fuss ought to be made, I think.