- Calculating Motive Power Requirements
Re: Calculating Motive Power Requirements
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You might also keep in mind that your "ruling grade" might not needfully be in
sight on your layout. It might be over the horizon towards the next division point.
On Sat, Aug 15, 2015 at 10:59 AM, jimbetz jimbetz@...
Often using any kind of "prototypical practice/methods" results in
that don't really "work" for the layout. At the very minimum you will
make some decisions that "map" the horsepower in the locos to the trains you
are able to run on your layout - because, among other reasons, the prototype
ratings don't apply directly to our model trains.
I'm saying that using the same formulas that were used on the prototype
often results in 'errors' when applied to our layouts.
Another approach is to do -actual- motive power measurements ... on
This is easily done by first finding the ruling grade and then pulling a
up that grade and changing the number of cars until the loco handles it
without? any slipping is up to you/the layout owner).
Finally - create "locomotive cards" that are the same size as your
car cards and
include the rating/pulling power for the loco. It helps if all of the
cars on the
layout are the same weight (for the same size car). Using a rating that
on the edge of being the max the loco can carry may result in "emergency
for a helper" which although fun can seriously affect the 'flow' of the
decide whether or not you want this to happen and set your ratings based
that decision). The loco card "travels with the loco/train" just like
the car cards -
so it is always available to anyone (the YM/hostler?) who is making the
about what power to use on the trains. (Many layouts also have "caboose
Many layouts include specifying the locos that will be used on trains
made up during the session in the 'packets of stuff' that are used to
trains to operators and/or given to the yards to use to make up the
Most layouts do not have much capability for/include in the
ability to add helpers for "Just The Grade(s)" ... and so the motive
to the train is done in the originating yard or staging.
With this approach what you do is to "assign enough power for the
train to get
itself over the RR". And, usually, the layout owner decides to not
power requirements for different directions (even if that is possible) -
if for no
other reason than to keep the number of locos 'balanced' on the ends/in the
yards. But some Ops include "light power moves" to re-balance. *G*
I operate on a lot of different layouts. One of them has a helper
many of the trains truly -require- a helper in order to get up the
won't make it without one. The way the Op works is that the train pulls
the departure point in the yard/town, the helper is added (and at the
placement/specified place in the train), and then clearance to proceed
At the top of the grade the helpers are cut off and the train proceeds
them. This is an "all steam" Ops (OK, only mostly steam) and so each
has its own crew/engineer (no consisting with the head end).
Helper operations can be/are a lot of fun - but in order to do them
effectively you may have to add Ops jobs such as "hostler" and "Helper
Engineer(s)" ... and you also have to allow time in the schedule to
helpers. Luckily, it is usually fairly easy to find a window where a
set can be returned back down the hill - where it goes into the engine
to wait for its next assignment. *Great Stuff!!!*
- Jim B.
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