Push or pull in "lashup"

In a hi-rail setup, it doesn't matter as much, but I prefer the faster of the two up front when MU'd. When I run my scale-wheeled locomotives MU'd,  the faster ones tend to push the slower ones off if placed in the rear. Interestingly enough, I've heard that some DCC systems have adjustments for locomotives when being MU'd but I haven't seen anything like that in DCS or Legacy -- at least not yet..

Call me stupid but what is the advantage if one loco has to drag the other? Would not a simple dummy be better? I have not tried powering a train with two locos for this reason.

midnightwrecking posted:

Call me stupid but what is the advantage if one loco has to drag the other? Would not a simple dummy be better? I have not tried powering a train with two locos for this reason.

Sorry Midnight, no stupids on this forum. 

Consider you might have two favorite steamers, which unlike diesels, there are no dummy equivalent.  So you want to doublehead them over your mountain(s).  You put them together but find one runs slightly slower/faster than other.  Thus my philosophical question of who goes first front.

midnightwrecking posted:

Call me stupid but what is the advantage if one loco has to drag the other? Would not a simple dummy be better? I have not tried powering a train with two locos for this reason.

If the layout has any grades, a single loco may not be able to pull a train up the grade unassisted, especially if adding a dummy to the mix which are typically much heavier than a typical freight car.

I personally would put the faster of the two in the lead, but if the difference in speed is more than slight, I wouldn't MU/Double Head them. In the model world we would be MUing them, in the real world MUing, would be Diesels, all connected together through the MU cables, with one engineer, typically in the Lead locomotive controlling all the MUed units. Double heading, in the real rail world would typically be Steam, but any combination of locomotives, where each unit has it's own crew operating it.

If there are crewed locomotives placed mid-train and/or on the rear, those would be considered "Helpers". If the Mid-train, and/or rear units are controlled by radio(without on-board crews actually operating the units) from the Lead unit, then those would be considered DPU's(Distributed Power Units).

How the various units are operated, would effect the proper terminology about what type of service the unit is being used in.

Doug

I have only MU'd a couple of 3 rail MTH engines a couple of times (different engines each time). I ran them at the same speed first, following each other, and they were close enough I didn't think it would matter which one went where? I didn't give it much thought, but I really haven't done much MU'ing either.

put the faster one against the train  the weight of the train should cancel out the speed difference and the slower one out front. works for me ...

AGHRMatt posted:

In a hi-rail setup, it doesn't matter as much, but I prefer the faster of the two up front when MU'd. When I run my scale-wheeled locomotives MU'd,  the faster ones tend to push the slower ones off if placed in the rear. Interestingly enough, I've heard that some DCC systems have adjustments for locomotives when being MU'd but I haven't seen anything like that in DCS or Legacy -- at least not yet..

The ERR TMCC upgrade does have adjustments for speed matching when running as an MU.

The MTH system watches the flywheel for speed control which most DCC systems that I know of, don't. Now I do still see engines that run at different speeds. I usually run them around the layout spaced an 1" or so apart to see if they match together well. I personally run the slightly faster engine at the back of the head engines so the weight of the train, ties it down a bit. That engine will be doing more work. I run 2 rail so the wheels can slip as needed.

If the speeds are way off, they won't work together well. That can also show that there's a problem developing in an engine.

If both are MTH engines and the   scale speeds are different  I wouldn't do it.  It's just too expensive to replace burnt out circuit boards.      It's those darn traction  tires, they just don't slip and therefore are not very   forgiving,    I've had terrible luck with lash-ups.

Interesting info, thank you all.

In this video, these are all MTH multi units full dcs command....excellent runners from  scale 1mph up to my max of 45 scale mph.

If you use the orange module to program your Legacy command system, they contain speed data so that when you build a train, it'll set the speed curves to be the same, and impose a speed limit to the train of the top speed of the slowest locomotive.  I have run the VL BB, a Heavy Mikado, and B6sb in a train together.  Plus the remote will tell you it has set the speed on the switcher to road speed when you add it to the train.  I know you can add the locomotives without the orange module, but the manual says to use it for this reason.

But as for when I run a MU with conventional locomotives, I put the slower one in the lead, much for the same reason Joe does, the long train helps slow the faster one down and thus it doesn't push too hard on the lead engine.