If one were to buy two identical DC engines for the purpose of running them in tandem, i.e. two GP9s or an F7-A unit and an F7- B unit, could one expect them the run together without fighting each other?
I understand that in DCC one can program each engine to supposedly duplicate another, and I am not sure how that works, but the main question is for DC.
Thanks
John
In an ideal world, yes. However it’s hard to find two locos that will run the exact same speed. I’ve had locos that were close enough in speed to run together with no problem. I’d generally have the slowest of two in front. Why? The faster one would be pulling the brunt of the load and naturally would be slowed down. Putting the faster one up front has the slower one pulling most of the load and the fast one literally spinning it’s wheels. At the other end of the spectrum were two identical locos (right down to the cab numbers) that were so different in speed it was like Wile E. Coyote chasing the road runner. And we know how that ended. I had to put a fair sized resistor on the motor of the faster unit to slow it down.
I occasionally operate on a neighbors DC HO layout. Most of the trains are 40 to 50 cars long and usually have 3 or 4 engines. Most are reworked Athearn blue box SD’s and perform well together. I think your best bet is to use diesels from the same manufacturer, do a thorough job of tuning them and you shouldn’t have a problem.
John,
I have an Athearn BB F7-A and F7-B that I run in tandem. One is slightly faster than the other, but close enough in speed that they run fine together. I run the faster one in front because they are close in speed. The faster one does not spin its wheels. I do it this way because I don’t want the faster one pushing the slower one. I would like to suggest, if at all possible, that you test the locomotives to see how close in speed they are. IMO I don’t think two locomotives with a significant difference in speed would work well. You might be able to deal with resistors, but I can’t. RTR was created of a reason and I’m it.
Glenn
John,
Despite the views of some people in this hobby, two locos need not run at “exactly” the same speed to run just fine together.
I have been in this hobby since the 1960’s, and still operate in DC. Nearly all my trains are pulled by more than one powered unit. I typically pull 30 to 70 car trains on my layout.
Most of my diesels are matched sets of the same loco from the same manufacturer, and most are three or four powered units. But that does not mean different brands will not run together.
To answer your specific question, if you bUy a DC set of F7’s from lets say Walthers, YES they will run fine together.
That said, sometimes you may get an odd ball with a problem, but generally they will run close enough to work fine together.
I actually double and triple head lots of different steam locos of different wheel arrangements and brands with no problems.
A few hints - in my view don’t worry about which is faster or slower in front, it won’t make any difference.
Are you pulling enough cars to “need” two or three locos? If you are, this will smooth out any minor differences in performance even more.
Do you have a GOOD throttle that provides smooth slow starts? This makes a big difference. If two locos don’t start at a similar speed, this causes problems starting at stopping, creating more of sense that they don’t run well together. But better throttles tend to smooth this out.
You will find a s
If one were to buy two identical DC engines for the purpose of running them in tandem, i.e. two GP9s or an F7-A unit and an F7- B unit, could one expect them the run together without fighting each other?
Yes…I do it all the time.
You are concerned about what is essentially a non-problem. Slight speed variations are nothing to worry about. Identical engines will run nicely together unless one has a problem.
You can even run different brands of locomotives if the gear ratios are close. For example, a 14.1 gear ratio engine can usually run with a 12.1 gear ratio engine if the speeds are kept to 1/2 throttle or less.
There are some mitigating issues however:
For example, some DCC ready engines may drop so much voltage on DC that it takes over 1/2 throttle to even get them to move. In this case, I would remove the decoder so the unit would perform well on DC.
Another example are Athearn and P2K 4 axle locomotives. Both have identical gear ratios. The problem is some of the P2Ks have a lighting board with 8 diodes. The idea was to prevent the engine from moving until the headlight comes on. Removing the board allows the engine to start at a lower voltage and the engine will have increased DC performance. Now the identical gear ratios can be used to full advantage.
I run DC, and I"ve got two Genesis F-3 A/B diesel sets that I run in tandem, plus a dual-mode BLI E-6 A-B-B (2 units powered, 1 dummy) that heads my City Of San Francisco ‘streamliner’ . No problems at all. I even doublehead a lot of my steam with no problems. No, the locomotives do not run EXACTLY alike, but so close that I have no problems with jerking or stringling.
DC isn’t really that ‘prohibitive’ about multiple power units.
Tom
Hello John,
The answer is YES
A DC Bachmann FT A-B-B-A lash up.
A Walther’s FA FB FA lash up
Athearn BB PA-PB-PA
Hope this helps
LION runs MUd locomotives and now subway cars with no problems… but…
Always a “but”, isn’t there? LION uses gaps in his tracks to stop trains in the correct places. If you are using gaps to position a train in say a hidden storage yard, then one engine would gap out and the other one would dry to push a dead load which it cannot do.
The LION has permanently tied locomotive sets together A-B-A and A-A with drawbars and a hard wire connection across all of the units. This may not be necessary for what you are doing, but just to remember this issue if you use gaps to position trains. LION puts a rectifier across the gap so that trains can leave when the power is reversed. It works very well with hidden staging.
On the Route of the Broadway LION, all of my subway equipment has either one or two powered cars, and they were built up into sets without a lot of concern for where in the consist the power cars were located. LION gets away with this because of the drawbars and jumpers between the cars. As far as power is concerned he has a single unit with 48 wheel pick-up. Moving this consist to and from the layout is another story.
ROAR