That is an excellent explanation!
Bob A
In a message dated 2/17/2014 12:17:09 P.M. Eastern Standard Time,
runextra@gmail.com writes:
Let me see if I can throw some light on this common misconception about
different Hp locos MU'd together.
1. Think of a man pulling a heavy wagon with a rope. The wagon is just a
little too heavy for him to move. So he gets his 12 year old son to help.
Now both the adult man and the boy pull on the rope and together they move
the wagon. The much bigger man is pulling more than the boy is pulling but
both are pulling at their "maximum rated output". Furthermore it does not
matter whether the boy is pulling on the rope behind his father or in front
of his father. The results are indentical.
2. Think of a man and a boy riding on a two-seater bicycle. Both of them
are pedaling. Obviously the man can pedal with more power than the boy but
the pedaling boy does not drag on the man, the boy is producing his share of
the total effort.
3. Unlike an automobile, there is no direct relationship between the
locomotive speed and the speed of its di esel engine. IE, the loco wheels are
not geared directly to the engine. In any throttle notch (diesel engine
speed) the loco itself can move at any ground speed. Depending upon the load
it
is pulling and the track grade it might move at 10 mph or it might move at
60 mph in the same throttle notch (same diesel engine rpm). The throttle on
a locomotive is really a horsepower selector. For any specific throttle
notch the loco's governor (or computer now) guarantees that loco will put out
a specific percentage of its full rated Hp. So if you have a 4000 hp loco
and a 1500 hp loco operating together the smaller one does NOT drag down on
the larger one. The smaller one will pull its proportional share of the
load at whatever speed the train is moving.
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