How many locos?

[Anonymous]

I've been in the hobby for a while but now am trying to run a more prototypical RR. An area of the hobby I'm not sure of is how to determine how many locos to la***o my consist. I know the size of the engines is a factor but I was wondering to figure out how many to put on a train.
Andy

[Anonymous]

You forgot to mention what scale you model.I model HO, and most motive power should be capable of pulling 20 or more cars per loco, so I would say this is something that is personal preference. I run both extremely long(20 to 40cars), and I run short trains(1 to 10 cars), and both of which are not unheard of in prototype. Hope that helps!

[Anonymous]

Sorry I left that out I do model in HO, in your 20-40 car trains ho many locos do you have leading the train? Is there like a ratio like every 10 cars you add another locomotive?

[CBQ_Guy]

Here is an unofficial rule of thumb which seemed to be used on the old Burlington route, as far as their passenger trains: One E-unit per every five passenger cars.

[METRO]

Depends on a multitude of things, weight of the cars, importance of the train, ruling grade all need to be factored in. If you really want to run a prototypical line look for old rulebooks online or look in photos to see how many units your prototype lashed up.

On my line there is a lot of mountain running and fast commuter trains, which run in fixed trainsets that are terribly overpowered in order to accomplish speed over the grades. My fastest long distance passenger liners work on Amtrak's rule of one unit to every 5 or so coaches.
One general rule I have heard for reasonably fast freight is 3hp per ton of hauled tonnage (I think this was the UP's blocking instructions to the RI if I'm not mistaken)

[Eriediamond]

Another reason for multible lash-ups is for nothing more than moving a locomotive(s) to different locations for various reasons. Ken

[Anonymous]

Thanks for all the great posts. The one engine per 5 passenger cars is something new to me so I'll be adding another engine to my passenger consist.
Andy

[DSchmitt]

One factor is the number of locos needed to pull a train of the length you desire on your layout. Model locos do not necessairly match the prototype in pulling capacity. Some will pull more, some less. Sometimes the difference is siginificant. Also two models of the same prototype will often have different capacities.

Another factor is the prototype: For the prototype, John Armstrong gives a typical example for level track: A single 3000 HP unit will move 4760 gross tons at 34 MPH. Since most track is not level he gives a typical rating as 2000-4000 tons per unit where the desired speed is over 25 MPH.

Both grades and higher speeds reduce the ratings for a loco.

The typical train on a home layout, or even most club layouts, is short by prototype standards. Most model trains lengths probably would justify only one loco on the protoype. However just as we selectively compress our scenery, we compress our trains. Most people perseive a model train as longer than it really is. So we might use say a 20 car train to represent a 100 car prototype. We might reduce the number of locos too (say from 4 to 2) but we don't have to, and probably shouldn't if reducing the number of locos destroys our perseption of the model as representing the prototype.