Running conventionally, with my ZW-L set to exactly 11.5 on the throttle ring, the two trains below will circle my big (141 feet around) loop at exactly the same speed. If I space them "on opposite sides of the loop" - about 60 feet of tgracki between them - more than an hour will go by before one meets the other because of tiny differences in their speed. A simple calculation shows that is a speed difference of only about 1/2 mile per hour. For the video, I set them only about five feet apart - as close I can set them, for while they orbit the entire loop at the same speed they slow down and speed up on slopes differently, and drift relative to one another about four feet each way. On most days when I am in my trainroom, even though I have only three track loops, I set four trains going, "unsupervised" in the sense I'm paying attention to working on my layout, and let them chug away fro hours - they make good companions while I concentrate. I nearly always use a combination of locos that will run at the same speed (I have many) on my big loop, like this. After the video I talk some more about the details of this way of running trains that interest me and have another video that is even, ah, more interesting, I think.
The two locomotives in the video are a Lionel 0-4-0 shifter and a hybrid - an unmodified WBB Baldwin ten-wheeler chassis fitted with the body from a recent Lionel Mogul. since the Mogul body is 1/2 longer behind the drivers, I took the front pilot truck from the Mogul and made it a trailing truck under the cab. Tender is the stock WBB tender. It runs just like a WBB 10-wheeler (i.e., very smoothly) but looks better. It is one of my favorite locos.
-->Anyway, the diagram below shows the throttle setting versus scale speed curves for these two locos. In actually they are not perfectly straight lines as depicted here but I drew them that way here, for expediency in explaining. The important point is that they have different slops and they cross at a realistic scale speed - in this case at 11.5 throttle setting and a scale speed of around 50 mph - a bit high for a freight, but okay. Below a thorttle of 11.5, the WBB chassis is faster. Above 11.5, the Shifter is faster. I can set them up and vary throttle slightly around that point to speed up one relative to the other and position them on the loop just where I want them.
Thethe load (number of cars) affects the exact setting I need, but if they behave like this without load, they behave like this with similar loads, just at a point tha tmight have moved: with both loaded more the crossing point would be about 12, but still at around the same speed. Other factors matter, too (some locos change their throttle versus speed curve more than others are they warm up - my Lionel 3759 much more than any other). The power supply matters alot, too. I have plotted curves for ever loco I have with my Z4000. I'm having to do so again with my ZW-L. Serendipitously, its voltage chopping seems to make this "trick" work much better: yesterday I got 83 minutes of operation of the two locos shown before the shift finally worked half way around the loop and caught the WBB: that is a difference in scale speed of less than .4 mph.
Anyway, the videos below show another combination that is quite interesting: Railking PS2 Y6B and Legacy Southern Crescent (it's been repainted). The Southern Crescent has cruise and it is locked in and being Odyssey II, is not varying speed one iota, the Y6B will drift back and forthrelatively to this about two feet while orbiting like this. They are going about a scale 18-19 mph. The blue tape you see on the layout is distance markers setup for me to time speed, etc.
I realize someone inevitably is going to tell me that Legacy or DCS can do this with two or even three locos, etc., but that is not the point. I have the only universal control system made - it runs everything and it runs them the same way I did when I was eight years old, which is when I first figured out this "trick." And besides, it's a lot of fun!!!
