Re: [CBQ] Re: compatibility of engines

[<runextra@gmail.com>]

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 diesel 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.