# How effective is it pulling with two units?



## rva1945 (Feb 11, 2016)

I'm talking about models, not "real" trains.

They're motors and gears must be precisely matched, otherwise. the unit with less traction power it will slow the other down.

I'm still waiting for the FT-B unit to arrive, it is powered and analog. There are a couple of wires coming out from the A's motor terminals so its decoder will drive both motors.

But I'm serioulsy considering stripping the B from the motor and gears and leave it as a dummy B unit. I have F7 A and its dummy B unit and it pulls the freight train effectively.

What would you do?


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## D&J Railroad (Oct 4, 2013)

I would never put a dummy locomotive in my lashup. It only adds drag to the train and I know it's not pulling. 
On the flip side, would you put all dummy locomotives on your train? Then why put some dummy locomotives on your train?


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## rva1945 (Feb 11, 2016)

Well, I'm talking about the B-unit F7's and FT's were A's and B's working together, even if the B-unit is dummy, it adds realism, doesn't it?


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## raleets (Jan 2, 2011)

I have a couple of Bachmann Spectrum locos lashed back-to-back and they work beautifully together. Guess I got lucky.
Bob


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## santafealltheway (Nov 27, 2012)

as long as one isnt noticably DRAGGING the other, (you'll be able to hear it)


.... Its fine.


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## DonR (Oct 18, 2012)

My experience is with recent model Bachmann DCC
GP40s and GP30s. These are quite heavy locos
thus they have very good traction and are good
pullers.

You can expect a 2 loco consist of these locos to
pull 20 or so cars on a level track. Even more if
all have metal wheels.

I've seen a consist of 3 Bachmann GP40s pull
62 cars, about half and half metal vs plastic wheels.

I also have 2 Bachmann DCC FT A units that I
run back to back in a consist. They are very
closely speed matched from the factory. I suspect
your B unit will be closely enough speed
matched to be workable.

It is easy to speed match DCC locos if you have
a DCC controller with CV programming
capability. You'll be more
more pleased with your trains if you keep the B unit
powered. You can often improve performance by
simply running the locos and 'break them in' as we
used to say when we bought a new car. Also be
certain to use plastic compatible lube and oil to
improve performance.

Don


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## thedoc (Oct 15, 2015)

If you hook them to a heavy train, you'll only be spinning one set of wheels and will use less current. I don't have any "unpowered " units, so I don't know how they effect pulling power. I did have a steam engine with a very heavy tender, and when I switched to a lighter tender the engine could suddenly pull more cars.


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## Fire21 (Mar 9, 2014)

I have two Kato PA-1s and a Con-Cor PB-1 dummy. I've not run them all together yet because I haven't speed-matched the powered units, but when I run one and the dummy with my 5 passenger cars, the engine pulls the train just fine, no slippage. Seems to me the dummy is just another car for the engine to pull.


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## mesenteria (Oct 29, 2015)

rva1945 said:


> I'm talking about models, not "real" trains.
> 
> They're motors and gears must be precisely matched, otherwise. the unit with less traction power it will slow the other down.




Even with a poorer or slower performer in the pairing, the two together will outperform either one of them singly. The reason is that both provide tractive effort, and their effort is additive. What is undesirable is that the loco wishing to perform more quickly will possibly spin more or put more wearing strain on hits drive system if it is too heavy to spin.



rva1945 said:


> ...
> 
> What would you do?


I would either re-gear the slower unit or speed match it with the other in DCC.


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## NAJ (Feb 19, 2016)

I am all DC and using older AHM locomotives and I have a Dummy Unit on the rear of the train and have no issues with drag.
The Dummy unit is an old Bachmann unit and I removed the center gear from the truck assemblies and removed the motor wires, lubed the axles and it glides along smoothly with very little friction.

IMO Dummy units add realism if you do not have a complex DCC setup or do not want to try to control two locos on the same train/track.

There is no right or wrong,"Your Railroad, Your Rules", do what makes you happy.


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## Old_Hobo (Feb 20, 2014)

I would put the faster of the two in the front, and have it pull the slower one, rather than have the faster one pushing the slower one.


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## time warp (Apr 28, 2016)

Most of my freights run powered AA units, in these combos:

2 AHM C&O BL2s, 
2 CHARMERZ FA2s
2 Model Power F2s
2 Tyco NYC Sharks
2 Tyco Midnight Special Sharks

All of them run tail to tail with the faster unit in the rear, and the pulling ability is more than double what it is with single units.
These lashups run for weeks at a time with few issues.
I'm with D&J, I won't have a dummy in the consist.


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## shaygetz (Sep 23, 2007)

Proto 2K E8/9s, both powered...wasn't a load they couldn't pull...the ground would vibrate as they passed by...almost a narcotic...ahh, the bliss.


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## Old_Hobo (Feb 20, 2014)

Almost?


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## gunrunnerjohn (Nov 10, 2010)

Multiple units can really enhance pulling power, here's an example that I couldn't have done with one locomotive. 

115 O-scale cars in the consist. The second locomotive is in the middle of the consist, it'll come along after about 50 cars.


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## time warp (Apr 28, 2016)

Cool beans, John!


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## rva1945 (Feb 11, 2016)

Well, I tried it.

The FT A has a decoder and the B is analog and wired in parallel with the A's motor. Of course the B's motor had to be insulated form the chassis.

The A was a little faster than the B so I added a diode to its motor (in fact a couple of opposite diodes for both directions) and now they pull almost identically as a team. With this A+B combination all the freight cars can be pulled along the layout that includes some tight curves, while the GP9 alone and the F7 (with its dummy B) are at pains in some sections with wheelslip occurring.


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## CTValleyRR (Jul 26, 2014)

So, ONE decoder controlling the motors of both units? 

I hope the current draw isn't too much for the decoder.


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## rva1945 (Feb 11, 2016)

CTValleyRR said:


> So, ONE decoder controlling the motors of both units?
> 
> I hope the current draw isn't too much for the decoder.


I don't think each motor exceeds 300mA while the decoder is capable of 1.5A.


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## CTValleyRR (Jul 26, 2014)

rva1945 said:


> I don't think each motor exceeds 300mA while the decoder is capable of 1.5A.


Cool. I hope you're right!


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## mjrfd99 (Jan 5, 2016)

DC here also. Run 3 locos usually with a long freight drag. Sometimes with a 4th dummy.
To combine multiples I run the locos unhooked to see which is faster- put that at the head then #2nd then #3rd. Been doing that and all works well.


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## time warp (Apr 28, 2016)

CTValleyRR said:


> So, ONE decoder controlling the motors of both units?
> 
> I hope the current draw isn't too much for the decoder.


If they were open frame 3 pole it would be close, but there's plenty of current capacity to handle cans. Plus the current draw isn't going to be ×2, more like ×1.5 because there's reduced load on the pair of motors. They're running far below max current.


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