Is a steam engine an engine, or is it a transmission?
Until I saw this video, I thought of a steam engine as just that—an engine.
Then I saw how this wonderful little V-12, with its complex valve train and impressive miniaturization was powered by compressed air. Nothing wrong with that, as it wouldn’t be reasonable to expect that something as tiny and delicate as this mechanism could stand up to the ferocious impacts, pressures and temperatures of actual internal combustion. The little V-12, as wonderful and delightful a thing as it is, was not, in the strictest sense, functioning as an engine; for instead of making power, it was being powered by an outside force, compressed air. And as with all things in nature, nothing is free, so the power required to compress the air into the storage tank would have to be greater than the power the little engine could deliver (which, I suspect, is why a generator cannot power itself).
So, okay—a steam engine, such as the type which powers a Stanley Steamer, White or Doble automobile, would be very much the same. It doesn’t so much make power as it “converts” power from one form to another. Gaseous pressure, in this case, steam, is used to impart reciprocating and cyclic movement to a mechanism of pushrods, cranks, gears, etc. It is a clockwork powered by an outside force—and yeah, that’s why we call a steam engine an “external combustion” engine. But wait a minute; the combustion part isn’t essential. The thing will run just as well on any compressed gas, be it air, nitrogen, helium or the aromatic byproduct of Brussels sprouts. The power isn’t in the steam engine, but in whatever causes the pressure in the storage tank. I wonder, then; is a steam engine really an engine, or is it nothing more than a transmission?
More musing: A steam locomotive is a self-contained package that does it all. It takes wood or coal or oil and uses that fuel to heat a vessel filled with water, thereby converting it into the pressurized gas we call “live steam.” That’s the engine part. The rest of the mechanism; the poppet valves, pistons and the actuating arms that drive the big wheels, are but the engine’s transmission. Right?
Man, I really gotta start spending less time on the computer and get an actual life.
One could say the same about an internal combustion engine. It doesn't create energy or power. It simply converts the chemical energy contained in the fuel into heat energy which causes the working fluid (Air) to expand (Not unlike steam in the cylinder of a steam engine) producing mechanical motion.
The First Law of Thermodynamics says energy can neither be created nor destroyed, only changed in form. This is all we are talking about here, be it steam or internal combustion.
On that level, isn't any engine that converts the latent energy of dead dinosaurs whether in coal or petroleum - into useful motion a transmission? Internal combustion is like a pay-as-you-use lease agreement. Lease a car with no money down, and make lease payments as you use it up. External combustion is like a deferred purchase. Spend fuel now at the front of the car - use it later when you send the saved steam to the back of the car.
By the way, 150 years ago, do you think they called them 'steam engines'? Or just 'engines'?
One definition of engine:
" A machine that changes energy (such as heat from burning fuel) into mechanical motion" -Merriam Webster Online edition
so, air fueled, coal fueled, steam fueled, gas fueled - no difference - all are engines - if they make mechanical motion.
According to Wikipedia, an engine is a machine designed to convert energy into useful mechanical motion. I'm OK with that definition.
Transmission is a little harder to define. In the case of a stationary steam engine, I would define transmission as everything in the drive line starting with the belt coming off the engine's pulley and ending with the belt connecting the final machine to the line shaft as a transmission. On a Stanley or a locomotive, the transmission would only be what little is downstream of the crankshaft. Stanleys do have the axle geared from the crankshaft and a differential, so I guess that could be considered a transmission. On a locomotive, one pair of drivers is on the crankshaft. I suppose additional pairs of drivers linked to the first set could be considered a transmission.
To make matters worse, the mechanism in your computer printer is called a "print engine". And the printing press at a newspaper business is referred to as an engine.
I tend to call the things in cars and airplanes, "motors". That used to raise the ire of an old friend who had been a mechanic in the Army Air Force during WWII. In his training he had been given a pat explanation of what was an engine and what was a motor. He used to lecture me regularly. One day my wife was in the conversation and he said, "I know this doesn't make sense to you, but I bet your wife understands". She said, "Makes sense to me. That explains why they call those big corrugated planes Ford Tri Engines."
WOW! What a retort! I love it!
It mebbe goes back to the language origins of the words. Engine is probably French (Latin) origin, while Motor is German.
Detroit. They didn't call it "The Engine City".
Going back to original post, Bob said this about a locomotive's boiler:
"It takes wood or coal or oil and uses that fuel to heat a vessel filled with water, thereby converting it into the pressurized gas we call “live steam.” That’s the engine part."
I'd be interested to know what definition of "Engine" this fits.
As far as an engine vs. a motor..... I'm sure you could find grey areas there, especially when considering various dialects of various languages of various nations. Wikipedia was defining motors and engines with the same definition I gave above. Since that was not the original discussion, I did not get into motors. However, I use "Motor" to describe an electrically powered machine that converts potential energy into kinetic energy and "Engine" to describe all other machines that convert potential energy into kinetic energy. However, I do still use the terms "Motorcycle" and "Outboard Motor", just because they are the common terms to use and makes communication easier.
Ralph wins the prize - see:
i.e. e volution in language is the answer...Coke used to mean something different than the "coke" of today.
A steam engine is an external combustion engine.
A double acting two cylinder steam converter, pressure vessel device is equal to a modern day V8 engine/fuel converter in power strokes per each 360 both have 4 power strokes per each 360 degrees of revolution. What do you call a steam turbine? Dave
A steam turbine. Although, it is an engine in the strictest sense of the word.