Combined Pulling Power of Lashups?

The more horsepower and tractive effort (torque) you have, the more you can pull. That's why real railroads have trains being pulled by 1 or 2 or 3 or...locomotives. Simplistically, but truthfully, more engines (as in under several hoods) is the same as a bigger engine (under the hood).

Now, there are all sorts of physics factors at play here as to the net effect of stacking locos, real or model (and I am sure - and I hope - someone will tackle that here), but, yes, more is more. Why else would they do it?

D500 posted:

The more horsepower and tractive effort (torque) you have, the more you can pull. That's why real railroads have trains being pulled by 1 or 2 or 3 or...locomotives. Simplistically, but truthfully, more engines (as in under several hoods) is the same as a bigger engine (under the hood).

Now, there are all sorts of physics factors at play here as to the net effect of stacking locos, real or model (and I am sure - and I hope - someone will tackle that here), but, yes, more is more. Why else would they do it?

 My question applies specifically for model electric trains. MTH or Lionel trains do not have independent gearing so when a second engine pulls on the first one, the electric motor on the first acts essentially as a dynamic break on the second. 

Am I all wrong here?

Question: what is independent gearing ? I have not heard that term before.   Thank you.

Clem

clem k posted:

Question: what is independent gearing ? I have not heard that term before.   Thank you.

Clem

For example, a real Locomotive has a a Diesel engine connected to a generator which provides power to traction motors. Those motors don't have a transmission, but they do have a gearbox that has reduction gears, a flywheel, reverse, and a neutral. All items important to lashups right?. 

Our model trains have two or three gears only and no neutral gear or ability for the trucks to just "coast". 

When you combine engines in the early same train, they work together. There can be issues of faster engines working harder with slower ones. If they run even close to the same speed, their power will combine and be able to move much more train.

 I run several engines all the time so that my engines don't have to work so hard, or wear out faster trying.

JDF posted:

clem k posted:

Question: what is independent gearing ? I have not heard that term before.   Thank you.

Clem

For example, a real Locomotive has a a Diesel engine connected to a generator which provides power to traction motors. Those motors don't have a transmission, but they do have a gearbox that has reduction gears, a flywheel, reverse, and a neutral. All items important to lashups right?. 

Our model trains have two or three gears only and no neutral gear or ability for the trucks to just "coast". 

JDF

A real locomotive does not have "a gearbox that has reduction gears, a flywheel, reverse, and a neutral."  Real traction motors on diesels have a pinion gear on the traction motor that is in constant mesh with the gear on the wheel set.  Reversing is done electrically and there is no neutral or flywheel.

Most of our modern O scale models of diesels are similar.  They have one motor per truck instead of per axle and have a flywheel on the ungeared end of the motor.  The models typically have worm gears on the motors rather than pinion gears.  Just like the real thing the gearing is in constant mesh and reversing is done electrically.  It is common for a manufacturer to use the same motor, gear ratio and wheel size for most or all of their diesel models.  Therefore modern O scale diesel locomotives of the same manufacturer tend to run together very well.  

And yes, if you have two locomotives that produce 2 pounds of drawbar pull each they can produce up to 4 pounds of pull together.

The more engines in multiple unit (lash-up) the more you can pull. However, too much amperage will, hopefully, trip the breaker on most transformers.

Interestingly, I have found that with my K Line 0-4-0 T Porters, that 2 or 3 of them can pull more cars double or triple headed, than the same locomotives can pull cumulatively in separate trains. It doesn't make any sense, but that has been my experience. IIRC, I found the same thing with the little RMT Beeps.

Doug