If it were
not necessary to create draught by reducing your exhaust nozzle, your
engine would run much nicer and be much more powerful if your nozzle was
not reduced at all. However, you must reduce it sufficiently to give
draught, but don't impair the power by making the engine clean its own
flues. I think ninety per cent of the fires started by. traction
engines can be traced to the engineer having his engine choked at the
exhaust nozzle. This is dangerous for the reason that the excessive
draught created throws fire out at the stack. It cuts the power of the
engine by creating back pressure. We will illustrate this: Suppose you
close the exhaust entirely, and the engine would not turn itself. If
this is true, you can readily understand that partly closing it will
weaken it to a certain extent. So, remember that the nozzle has
something to do with the power of the engine, and you can see why the
fellow that makes his engine clean its own flues is not the brightest
engineer in the world.
While it is not my intention to encourage the foolish habit of pulling
engines, to see which is the best puller, should you get into this kind
of a test, you will show the other fellow a trick by dropping the
exhaust nozzle off entirely, and no one need know it.
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