HO DC
Whenever I put a couple of say, Y6B's, on the same track/same direction, one is always slightly faster than the other at any given throttle setting.
If I want to run a couple of Locos on the same track (no crossovers], under DC semi 'autopilot',ie, I can wander off & come back & they haven't collided - I am aware that there are electronic units you can wire into the track that will cut the power to the 2nd 'faster' loco if it gets too close to the 1st. Then release it when a predetermined spacing has been achieved.
However, I am curious as to whether anyone has tinkered with the idea of putting something on board the Loco in the wiring circuit, such as a small variable resistor??, so that you can fine tune the current to the motor & if possible, get the Loco[s] to where they will circulate at resonably close to the same speed for any given throttle [cab] setting.
Before I get swamped with go "DCC", could the question above be addressed?
Tanked
Tanked,
It would not matter. You will never be able to control all the variables of rolling resistance, electrical pickup, etc, to the point where two trains on the same loop of track will never catch up one to the other. I doubt the speed matching of DCC could even acomplish that.
Left alone long enough, one will always catch up to the other. simple changes in temperature as the locos warm up, or in the rolling resistance of differen cars at differnent speeds, etc, would make it an endless exercise in ajustment that would defeat the purpose.
As a DC operator that does a lot of double heading and multiple unit operation, slight speed differeences have no effect when the locos are coupled, but apart you will never get them to run that much the same.
Sheldon
This technique has worked for me, and I see no reason why it shouldn't work for anyone.
Start with each locomotive running light, and see which one is faster. Add some cars to the faster locomotive, possibly including a caboose with axle wipers for lighting. When the two locos are running at very nearly equal speed, start adding cars to both, maintaining their speed equality until the longer train reaches the maximum length your sidings and yard tracks permit. If you feel the shorter train is too anemic, add 'drag' cars to the longer train (axle wipers on unlighted cars work well for this) and move the replaced free-rolling cars to the other. It may take several hours of adjusting, and the results will never be perfect but can be made very close.
That said, if you try to arrange totally hands-off operation, even with speeds matched by rheoststs or potentiometers on the locomotives (NOT a good idea - they will generate heat) all it will take to completely invert the applecart is for one locomotive to stall for any reason. Murphy loves this sort of situation, it gives him so many possibilities to demonstrate his law: What can go wrong, will go wrong. Ultimately, the only totally fail-safe solution is to install track occupancy detectors, a working signal system and slow/stop track circuitry.
Even then, the trains won't keep running. If one stalls, the other will find a red absolute stop short of a rear-end collision and both will simply sit there.
IMHO, even 'trainwatching' operation requires continuous human or electronic interaction if more than one train is in motion at the same time.
Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL, with auto-stop)
tomikawaTT That said, if you try to arrange totally hands-off operation, even with speeds matched by rheoststs or potentiometers on the locomotives (NOT a good idea - they will generate heat) all it will take to completely invert the applecart is for one locomotive to stall for any reason. Murphy loves this sort of situation, it gives him so many possibilities to demonstrate his law: What can go wrong, will go wrong. Ultimately, the only totally fail-safe solution is to install track occupancy detectors, a working signal system and slow/stop track circuitry. Even then, the trains won't keep running. If one stalls, the other will find a red absolute stop short of a rear-end collision and both will simply sit there. IMHO, even 'trainwatching' operation requires continuous human or electronic interaction if more than one train is in motion at the same time.
I agree with Chuck completely on this, and as a person interested in display running and operational running it is clear that DCC, in and of itself, provides no advantages here. Again, on DC or DCC, let to run long enough (hours?, days?), one will catch the other, by speed difference, changing conditions or mechanical failure.
davidmbedard Unfortunately, and even ATLANTIC CENTRAL agrees.......if you want it ALL, you need DCC. David B
Unfortunately, and even ATLANTIC CENTRAL agrees.......if you want it ALL, you need DCC.
David B
OTOH, if you DON'T want it, "ALL," analog DC is likely to be the simpler solution - and doesn't rely on mysterious black boxes to deliver what you DO want.
DCC has a lot of 'all' that I don't want, don't need and can't use in my business - and using it would prevent me from using simple, cheap circuits (two diodes, two resistors) to do things that DCC needs either special black boxes ($$$) or a computer interface to accomplish.
Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL system)
Well, here is what I would like to be able to do in HO DC - basically I would like to be able to sit back & watch up to 4 steam loco based consists circulate simultaneously, with minimum intervention on my part.
Something about movement & the locomotion of valve gear & more than one moving object on the layout appeals.
Some railroaders are very much hands on shunters, controlling everything at any point in time.
I am the other extreme. I prefer to set up then watch, 'hands off'.
I am pondering 2 independent layouts on the same board so that I can at least run 2 locos simultaneously. If I put in the 'distance sensing' electronics then probably be able to run 2 consists per track at the same time.
My layout is a long double track mainline which allows two trains to operate each on its own "route". But for even more display value running during shows, there are cutoff tracks which turn it into four seperate routes in stead of just two.
And I am considering doing what Chuck discribed, adding auto slow/stop circuits to my signal system that would allow two trains to operate on each route without collision, again, for shows, openhouses, etc.
My layout is also designed for full operation by a crew of operators. There is no reason that a well designed layout cannot do both. And, with DC or DCC, good display operation requires seperate routes, automation, or both. Relying on equal loco speeds would be far to risky for me.
Just jumping back in, slightly , to describe the other extreme of analog DC, MZL system.
My track schematic is one big loop, partially single-track, with six staging areas, three of which are back-in/back-out. There is only one reversing connection, which most locomotive-hauled trains have to use in order to arrive 'on-stage' through the appropriate tunnel portal. Operating it to the prototype's September, 1964 timetable (24/30) calls for train movements choreographed like the Bolshoi - there are well over 100 trains on a slow day!
Display/show operation is the impossible dream. The layout is surrounded by windowless walls, and the aisleways are NOT designed to handle more than a few visiting in-laws or operators.
Every locomotive that is in motion has its very own controller - even if it's operation is of the 'fire and forget' variety (Start at a visible station, auto-stop at the next station or in staging.) The only speed matching (if you want to call it that) is between main and helper locos on the upgrade between Haruyama and Tomikawa, and between the traction motors of some twin-engined diesel-hydraulic and catenary electric locos. Oops - almost forgot the DMU and EMU trains with multiple powered cars. Since I operate at prototype (restricted!) speed, they tend to match themselves without any problems.
Since my model railroad persona is mainly dispatcher, my layout suits me. It definitely isn't everyone's cup of o-cha.
Chuck (Modeling Central Japan in September, 1964)
First, the only drawings I have of my layout are 24 x 36, three pages because it is three levels. I have no way to scan them and I'm not even sure how to post them on here if I could scan them. And, clarity would most likely be an issue.
Send me a private message and I will try to make a simplified sketch to e-mail you directly.