In my particular case, I am talking about a new 4 engine Kato F3 lashup pulling the California Zephyr. Each of the two A units and two B units are powered. When I first set up the track and ran the trains I found that while close, some were a little faster than others. Does it really matter if the fastest or slowest A unit is first in actual use in respect to unequal loads being put on a single engine?
Well to me it always seemed to work better to have the faster engine first to keep the couplers taut. But I don’t know if it makes a great difference.
<> p.s. I’m assuming you’re running in DC?? If you’re in DCC you can use the speed and momentum CV’s to speed match the units so all 4 will start, stop and run together pretty much perfectly.
This is a major problem in N scale where nothing is the same speed and that speed varies GREATLY from one manufacturer to another. I have resigned myself to the fact that there are certain engines that can’t be run together no matter what. Never had this much of a problem in my HO days.