Double Heading or DPU (distributed power unit) with worm drive gear boxes.

[Trainman 864]

I did a quick search but nothing showed up - I would like to run more prototypical longer consists by double heading my Aristocraft 66's. I've had conflicting advice on how to do this - or if it is even possible. Some sources say the locos will 'fight' each other and cause premature wear on the gearboxes and wheels.

Could it be done by binding both locos to a common transmitter - or would it be neccessary to juggle two transmitters?

Many thanks for any help or links to more information.

 

[PhilP]

Hello John,
Yes, you can do this.. Both 66's would need identical equipment in them (though you could get away with a single soundcard, if you wished).
The caveat's:
Both sets of batteries bought at the same time, and having about the same amount of use..
Both 66's to be about the same age, and more importantly, wear..

Then bind both receivers to the same transmitter. Put the units on the track about 3 feet apart, and then run them back and forth. - If they run at about the same speed, so take quite some time / distance to close, or open, the gap between them, then you are good-to-go.

The problem is, many of these units have had a hard-life, and the drive-train will be worn. - One way round this, would be to put DCC decoders in the units, then you could customise the speed-curves to match. This would probably need checking (at least) once per running season?

PhilP.

 

[Rhinochugger]

Let's think this through.

So, a single loco with the entire train will cause quite a bit of drag on the drive train, up to the point that the wheels spin.

Take two locos, neither of them spinning their wheels, the load on the drive train has to be less than the first situation.

If you use two transmitters, you can manually adjust the speed of the first loco by watching the coupling to the second one, and ensure that it is pulling just enough to keep the coupling firmly tight at all times.

 

[Greg Elmassian]

So there are a lot of old wives tales about this. (thankfully none were expressed already)

Phil got it right, he used the word "about".... the first old wives tale is that if they are not running at exactly same speed it won't work. Those people will "prove" it to you by taking just the 2 locos, place a few feet apart and say "see" if they don't keep the exact distance. They further "prove" it to you by coupling the 2 locos and watching them "fight" at the coupler. This will indeed happen.

The true situation is that under load (meaning pulling a train), the loco tend to contribute pulling power and even out quite a bit. The "faster" loco will take more of the load and slow down, more closely matching the "slower" loco.

The heavier the train, the more this "equalizes"

So, do not throw your hands up in frustration if you cannot get them to match each other exactly when they are not pulling a train.

As long as they are "about" the same and you pull a train worthy of double heading, you will most likely be fine without a lot of extra bother.

Greg