Is running two locomotives together (in tandem) a viable solution to pull longer consists up grades? Not sure about the two speeds being synchronized. It's DC. And the question applies to steam as well as diesel. Bob
Short answer: yes. If the speeds of the locos are very mismatched then the faster one will spin its wheels and this may either ruin your experience of it, or cause the faster engine to overheat after a while. At some point you decide if it doesn't work. If the speeds are only somewhat mismatched, it usually makes sense to put the faster loco(s) in front to avoid uncoupling problems. A lot of people worry a lot more about speed matching than I think they need to. With better quality locomotives, it only really matters if you're doing helpers. That's my personal opinion.
Doesn't that just exacerbate the problem? Wouldn't it be better to put the slower loco in front, with the weight of train tending to slow down the faster loco?
I would put the fast one in front. Then it is pulling on couplers. The slower one in front, then the fast pushing one can come uncoupled when the knuckles get skewed. Or can even break the shank.
Try this two-part experiment. Take two speed mismatched locos, couple the slower one to a train and put the faster one on the track slightly ahead of the slower loco (and train). Run them around your layout and note the speed differential. Now, swap the positions of the two locos and run them again. Again, note the speed differential and see which configuration results in a closer speed match. Also, I believe you'll observe that coupling the faster loco ahead of the slower one, as you suggest, results in the faster loco trying to drag the slower loco running behind it.
Usually locos from the same manufacturer and same production run are very close in performance. Which is why I run Bmann Fs with Bmann Fs and Kato with Kato. It is also why when I built my test track there are three tracks of equal length side by side to match up the F or RS units as close as possible in sets. In my current layout planning there will be doubleheaded locos on the branch but only uphill. To me the slowest locomotive determines the train speed. Therefore the slightly slower one is in the lead on the uphill climb. If the 2nd loco is spinning its' wheels then there is a complete mismatch of locos and it shouldn't be doubleheaded with the first loco to start with. Both of my new 4-4-0s are planned to be doubleheaded and in testing I find them very close in speed match and pulling power.
I often run multiple units on DC without problems. I also try to run the faster engines in front. Keeping the couplers under tension is much safer than running them under compression, especially on curves. Of course with an A-B or A-B-B-A lash up where there's no lead/follow choice, I hope the engine speeds are close enough and any compressed couplers don't push sideways. I test different engines by setting them a few feet apart on a loop, then set the throttle about half speed to see if they get closer or pull apart. That quickly answers the faster/slower question.
Actually I was speaking from my own operating experience. Thus I want the faster engine in front, pulling. Having the faster engine pushing kicks the couplers off to one side. Then you can get an uncouple and I have even had a shank break. If speeds are too obviously mismatched, then I will not even attempt using them together.
Like others, I avoid mixing manufacturers. As a result my lashups all remain the same: LL E6 ABA LL C-Liner ABA LL Erie Built AA Kato F3/7 ABA or ABBA Kato PA/PB ABA Kato E8/9 ABA Kato GP-38/50 AAA MT FT ABBA IM FT ABBA Still only DC here. Multiple locomotives work great especially if you need the extra pulling power. And besides, it's more prototypical than a single unit.
Generally speaking I agree. I found a happy match with a Bachmann GP40 and a LL GP30, but that's probably going to be the exception. When I first started doing lashups, I did the test to see which combination resulted in the fastest speed and went with that. However, I recently changed my mind - for no other reason than I didn't like the look of the couplers when the faster unit was behind, pushing the slower lead unit. It just didn't look right, plus it did seem like it would have the potential of causing other issues, as Boxcab pointed out. There's reasons for both, but if the units are close to being matched I doubt there's much real difference to the locos.
Speed matching and thus pairing locomotives, is best done between locomotives from the same manufacture but remember; Atlas some years ago, went to a “Slower” motor and those locomotives will not pair-up with the older “Faster” motored Atlas locomotives. Now the older faster Atlas locomotives will pair nicely with virtually all Kato locomotives with the exception of some of the really old Kato locomotives some sold as Con-Cor, that will pair better with the newer slower Atlas locomotives. Then we have the Life Like/Bachman, Micro-Trains/Con-Cor, Model Power/Kato and Intermountain/Atlas (Older/Faster, Newer/Slower) pairings. Or any mix of any of the above. In other words; you pay your money and you takes your chances.
