I got two brand new DCC / Sound locomotives in the box. They are both SD40's made by the same manufacturer. Being they should have the same factory settings, shouldn't they be able to MU without making any speed adjustments?
Hello all,
In "theroy" they should...but in reality they might not!
The only way to tell is do a speed test on each one.
You can buy a speedometer that will give you the speed of each loco and then adjust CV's accordingly. These cost approximately $70.00. Money I could better spend on other items.
For speed tests I use an oval section of track and place each locomotive across from each other (if you have ever watched bicycle racing on a track they do the same thing- -where I got the idea for this method).
If you want the most "accurate" measure set both locos to the same address.
Choose a speed and let 'em go. If they are speed matched out of the box they should pass the same point opposite each other at the same time.
If they are not you will see one hit the opposite mark sooner than the trailing one.
At first the difference might seem small but after running in this manner for a few laps you might see a big cumulative difference.
From there you can decide which loco to "slow" through CV settings.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
Yes, they should. There is no requirement that two locos be in absolute lock step speed step by speed step. As long as one isn;t wildly different in speed fromt he other, they will run fine together. The two units plus the load of a train will even out any small inconsistencies.
Remember, people put multiple locoos on a train with DC, and there was no way to speed match DC locos, short of fooling around with diodes to try and slow a faster loco down, and it worked fine. DCC is NOT different here.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I tried it and it worked, I took 2 Athearn SD-40 HO RTR DCC/Sound locomotives and MUed them and they ran fine. I speed tested them by having one follow the other about 12" apart and they seemed to maintain that distance +/- 2" and I think that changed due to curved track and minor inclines. Then I took 2 Bachmann SD-70ace sound locomotives and did the same speed test and they MUed fine. On both tests, one locomotive was louder then the other, I just put them on the JMRI track and matched the sound levels.
Mu'ing? Didn't your parents give you "the talk"!? Obviously not otherwise you wouldn't have asked such a question.
I'm just kidding with ya
Yes you'll probably have to speed match the locomotives even though they are two of a kind.
I also suggest that you test them at multiple speed steps to make sure their power curves are similar.
The reason I say this is because at my club there's a few "speed matched" consists but the units have very different power curves abet they have the same top speed when you apply throttle one takes off the other slowly starts lumbering along, so when you change direction of something one of the units makes a loud grinding noise from it trying to drag the other unit.
Steve
If everything seems under control, you're not going fast enough!
jjdamnit For speed tests I use an oval section of track and place each locomotive across from each other (if you have ever watched bicycle racing on a track they do the same thing- -where I got the idea for this method). If you want the most "accurate" measure set both locos to the same address.
My aproach is similar.
I put two locos on the same track about 6 or 8 inches apart. Then go through the entire throttle range one step at a time and notice whether one or the other is gaining or losing ground at any particular step. Then I move the loco to the programming track and adjust the speed table accordingly. Lather, rinse, and repeat as necessary.
Many of my trains have particular consisted locos in particular fixed nose-to-tail or tail-to-tail configurations. These are speed-matched in their usual forward or reverse orientations for both forward and reverse directions of travel.
Robert
LINK to SNSR Blog
As Randy has noted, us DC operators run multiple locomotives on trains, too, and unless one of them runs at a vastly different speed than the others, I don't worry at all if they're exactly matched.
The grades and curves, not to mention heavy trains that actually need more than one loco to move them, assure that the locos will get along with one another, despite their minor differences.I run double headers, with or without pushers, and mid-train helpers, too - all-steam.
Wayne