Consist question dcc

[mf5117]

what are you saying ACY I have 7 GP40's Bachmanns and running them shows that they are matched pretty well . I run them on 18" and 22" rad and haven't seen any problems .maybe if it was an athearn or a bachmann then maybe a problem .I also have a couple of Bachmann GP30's BN that I consist and they run well aswell ...

[Freight Train]

Did I start this argument !!!!!!!!! HA HA!!!!!!!!

[jward]

Hmm thats funny I run 2 to 3 bachmann GP40's off my EZ commander and they seem to be matched pretty close .Just addressed them the same . the FT unit that came with the set ,and I bought a B unit off the internet and run them together consist and they run evenly . maybe I'm missing something but my Bachmann DCC locomotives being the same engines are geared and I guess you would say programmed the same and run great together .....

just because you have had this experience thus far doesn't mean it will always be true.

locomotives can vary in how they run due to a variety of reasons which i won't go into here. suffice it to say that the only way to guarantee that all your locomotives will run together is to program them to do just that. 

the situation you describe about similar engines running at similar speeds is often true, but often it is not. some brands have better quality control than others. until dcc there really was no way to guarantee that everything would work together, and often you had locomotive consists that fought each other. nothing has changed except the ability to compensate for that through speed adjustments.

want to see how closely matched your locomotives actually are? address them the same, then run them about a foot or so apart. i think you'll be surprised by what you find.

[Jerrys HO]

So true Jeff I have a Sante Fe and a Union Pacific and they are slightly different but when I hook them together they appear to act as one. I just put the slightly faster one in front. Jeff's idea of addressing the same and running together is a great way to figure which one is faster to allow the faster one to be connected in front if you don't have the ability to reset the speeds.

[mf5117]

jeffery I'll try that what you recommend ,running them a foot apart but I have never had any push any other off the rails or wreck any . maybe I just don't have enough experience , so hmmm I'll just enjoy my Bachmann Locomotives in HO and sit back and listen ... no worries happy railroading

regards   mark f

[ACY]

but I have never had any push any other off the rails or wreck any . maybe I just don't have enough experience

Although those things haven't happened, that doesn't mean your locos are matched, if they are not and you continue running them together then you can damage the motors and other components of the locos, it is easiest to see when you separate them and run them around the layout a few times and see how far apart they are or how close together they are.

[jward]

running the faster one in front is what we did for many years before dcc came along. if they are reasonably close in speed, the risk of damage to one or the other is minimal. remember, as recently as 10-15 years ago, dcc was rare and expensive. you had to run two locomotives together on dc, with no decoder settings to make adjustments in speed. what you got out of the box is what you lived with unless you wanted to take dratsic measures like remotoring or regearing them. about the worst thing that i have seen happen was the faster locomotive, if the speed difference was enough to cause its wheels to slip when couplers to the ohter locomotive, would get its wheels polished and wouldn't pull as much. that, and athearn locomotive which picked up power through the chassis needed to be turned so that all frames were the same polarity. otherwise, you'd have a dead short through the couplers if you were using kadee's metal couplers. (ez mate and other plastic couplers weren't available then)


oh the joys of the good old days.....

[Jim Banner]

Back when I ran short trains on dc, I used to test and rate matches between locomotives.  One section of my layout was a flat oval on a 4' x 8' table, about 20 feet of track.  A class 0 (perfect match) was when the locomotives stayed the same distance apart.  A class 1 (excellent match) was when the locomotives increased their separation by one foot or less per time around the track.  This was 1/20 or 5% difference in speed.  A class 2 (good match), a class 3 (usable match) and a class 4 (risky match) was when the separation increased by 2, 3 or 4 feet lap respectively.  Later, when we went metric, this system still worked using steps of 30 cm.  In those days, I had only a couple of dozen locomotives so it was possible to do the numbers for all possible pairs.  The only perfect matches were some Atlas/Kato RS-3's and Bachmann Plus Consolidations.  The Consolidations not only matched one another perfectly, they also perfectly matched the RS-3's.  Athearn locomotives matched other Athern locomotives to a class 2 match or better except one remotored relic from the 50's that did not match anything.  Roco's matched Roco's, even Tyco train set locomotives matched other Tyco train set locomotives at least class 3 or better.  But mostly interbrand matching was quite poor and if they did match at one speed they did not match at others.

After switching to DCC , speed matching became much easier.

Jim

[mf5117]

I must confess and become humble . On a 22" rad oval approx 24 ft of track ,my FT A-B unit running at start 1 ft apart running 5 laps around the oval at 30% throttle on the EZ commander. when I stopped them they were 4 5/8 " closer then at start . The GP40's I took ! as lead and ran 3 of them and the distances varied from 1 1/2 " to almost 3 " so I guess my Loco's aren't perfect like I thought . I guess I could really do some disecting and measure the gears and drives and really do some math . and wonder If they were put together early monday or late on a friday . So again I bite my tongue .

best regards mark f

[Jim Banner]

Only 4-5/8" difference in 120 feet?  That is a great match.  Microscopic differences in the fit of the parts, slight differences in wear and even the state of lubrication can make things worse than that.

Jim

[Doneldon]

"Only 4-5/8" difference in 120 feet?  That is a great match. "

I guess it is. It's about .34%. Imagine if you had carried a 99.66 average in school. I know that these percentages don't mean the same thing, I just picked the school average as a way to show how insignificant the error is. With only 128 speed steps plus variations in track, wire, motors, lights (or not), and other more subtle factors, I seriously doubt that one could program such compatibility between two locomotives.
                                                                                 -- D

[jward]

remember, ivory soap is only 99.44% pure...lol.

i would say those are close enough to not worry about speed adjustments. i would be happy if i had programmed two locomotives to run like that. when they are that close you really don't need to worry about putting the faster locomotive in front.