Lash up with TMCC or Legacy and longevity of Engines

Do you mean running 2 engines on the same commands.

Yes, I've done some lash ups, using my CAB1, programmed with the TR button, engine number, F button or R button , then set. Everything seems to work fine, but I was wondering if I'm introducing any excessive wear and tear on the engines by running this way. I've tried to NOT couple them together, and the two engines start off a couple inches apart, but no matter what combination of the lash up (Legacy and Legacy, Legacy and TMMC, or TMCC and TMCC, the distance slowly increases as I go around the layout. Should I be concerned?

Most diesels have very similar motors and gear ratios.  However, when you add speed control and all kinds of electronics between the track pickups and the motors, significant differences in speed for a given track voltage are possible.

Please search for my other recent posts on this subject.  If the difference in speed is about ten percent or less and you put the faster loco in front, it probably won't do any harm.  It's also a safer bet if at least one of the two locomotives has back-driveable gears.  The newer Legacy diesels with "LionDrive" have back-driveable gears, so the SD40-T2 and GP7 would probably be fine together.

I would be careful about lashing up two LionChief locos, a road engine and a steam switcher, or locos from any brand besides Lionel.  Definitely try them uncoupled first, at a wide range of track voltages.

Assuming that both locomotive run at the same speed, the lash-up will not hurt anything.  To be sure, test them.  Create your lash-up but do not couple the locomotives together.  Leave an inch or two of space and run them around your layout once.  As long as one doesn’t run away for the other or bump into it, they should play nice together.

@Danr posted:

Assuming that both locomotive run at the same speed, the lash-up will not hurt anything.  To be sure, test them.  Create your lash-up but do not couple the locomotives together.  Leave an inch or two of space and run them around your layout once.  As long as one doesn’t run away for the other or bump into it, they should play nice together.

Yeah, I agree with Danr, I do this before I connect my locomotives together to ensure they both are at the same speed.  One thing I have caught with this test is that I could have the momentum setting different for each which could cause one engine to start / stop at a different speed.

One other neat trick from this is that you can use this approach to run two trains on the same track and not have them run into each other.  Since the locomotives thing they are a train, they will continue to run at the same speed leaving the gap steady as they circle your layout.

One other test worth doing is note the amp draw with both engines running but not coupled. Then couple them together and see what they draw. A significant increase in current draw means they are fighting one another.

Pete

Engines in a Multiple Unit Consist (a “lashup” )  DO NOT have to run at exactly the same speed. A “faster” engine will pull on the train a bit harder than a “slower” engine. As long as no wheels are sliding, they can run like this all day.

My comment is that much of a speed differential (read: pulling differential) can contribute to rubber tires puking out onto the track. Especially prone to happen on curves.

As an aside, I have had 2 or 3 MUed Lionels with an MTH in front of them but NOT COUPLED. The TMCC dictates the speed and the MTH is very easily and quickly manipulated up or down on my iPad. That was  fun to try , but mainly for a video shoot.....not to be recommended  if you cannot devote some constant attention.

If you're going to try to MU dissimilar locomotives, one trick is to turn off cruise control.  A lot more variance in differential speeds is accommodated if you don't have cruise trying to maintain a constant speed.

Thanks for the tip, GRJ! If I ever get to running apples and oranges again, I'll try that.