Steam Engine – How Does It Work

Over the course of human existence, the most
significant catalyst for growth has been our ability to draw energy from our world. Taming
fire gave birth to the modern human and drawing power from the wind allowed early explorers
to travel the world, but today we are going to explore the history and science behind
one of humanities greatest inventions, the steam engine.
The evolution of the steam engine completely revolutionized our society. It opened new
avenues for trade and caused mass migrations of rural populations into the newly industrialized
cities. But what I find most fascinating, was the
lessons its evolution taught us about science and engineering. This is one of the first
practical steam engines, and it was used to pump water. The engine was incredibly inefficient.
This machine was not going to start any industrial revolution, but it found a niche in coal mining,
where it’s fuel was cheap and readily available. To investigate why this engine was so inefficient
let’s first talk about how it works. The engine takes the energy stored in the coal
and converts it to heat. That heat is then used to form steam, which expands into a piston
cylinder. Causing the pressure to increase and forcing the piston to rise against atmospheric
pressure. No mechanical work occurs on this stroke, because this chain can only transmit
force in tension. The power stroke occurs when cold water is
sprayed into the cylinder. This lowers the temperature, causing the pressure to drop.
Atmospheric pressure now pushes the piston back down.
We want to be able to quantify how much work is being done per cycle of this engine. To
do that, we plot the pressure and volume inside the piston cylinder for one cycle, like this.
The area inside is the work done, but this is the idealized PV diagram. In practice there
is a lot more energy being wasted. We lose a big chunk here because the steam
is prevented from expanding to it’s full volume.
A lot of energy is lost to the environment too. This is clearly visible with thermal
imaging. The effect is made worse by cooling the entire
cylinder with cold water. So an immediate improvement is to make a separate condenser.
Here the steam can be cooled without cooling the entire cylinder.
There are a lot more inefficiencies involved that reduce the total work done. Many of them
are unavoidable, but we can improve the situation by upgrading the piston cylinder.
The manufacturing techniques needed to bore accurate and strong piston cylinders were
not available in the early days of the steam engine. That changed when John Wilkinson invented
this machine. This boring machine allowed for precise machining or solid iron cylinders.
Which reduced steam leakage and made the piston cylinder stronger, thus allowing the max pressure
to rise. We are starting to see a steam engine capable
of sparking the industrial revolution, but this reciprocating motion isn’t much use
for most applications. Especially with this flexible chain connecting them. What we need
is rotational motion, which requires a very different set-up.
To convert this linear motion to rotational motion, we need a crankshaft and connection
rod. We have turned this piston cylinder on its side, so atmospheric pressure can no longer
force the piston back down, so we need to use steam on the return stroke.
This requires a control valve to control when the steam enters and leaves each side of the
cylinder. The valve is controlled by a cam. The steam engine is now working on both strokes of the engine, improving its efficiency and power, but
piston engines like this do not produce constant torque. They will pulsate in
speed and torque, during a single cycle, like this. This can cause vibrations and jerky movement.We can reduce this with the use of a flywheel.
Which stores rotational energy with inertia and evens the torque out. It’s
essentially a mechanical battery. David robert demonstrates this beautifully with a V8 solenoid engine of his own creation. Here you can see the engine will continue to rotate without additional power , but the engine comes to a dead stop without a flywheel attached. The development of steam engines taught us
a lot about thermal and mechanical efficiencies and you may think that steam engines have
become obsolete, but nearly all of our large power stations still use steam technology
to convert heat energy, whether that be from coal, nuclear or solar, to mechanical energy.
The technology has simply evolved into an even more efficient form, with steam turbines.
Thanks for watching, I have one last device I want to include in the development of steam engines, which is one of the most iconic inventions of the industrial
revolution, the centrifugal governor. I am already hearing the angry screams in the
comment section about me using the word centrifugal. So I am going to talk about this device in
a completely separate video to discuss the difference between centripetal and centrifugal
force. If you would like to see that don’t forget to subscribe. If you would like to see more content or support
Real Engineering. The links for my Patreon, Instagram, Facebook and Twitter accounts are

100 Replies to “Steam Engine – How Does It Work

  1. Hello, do you know what means the number in the red symbol of a star (like below the number 8) for the Wilesco characteristic steam engine:

  2. Great! Love how you came in from a very big-picture perspective and grounded it.

    How do you make these amazing animations? What package do you use?

  3. Hi Brian,
    great video as always, can you tell me the name of the Background music (it's stuck in my head)? – Thanks so much.

  4. There is absolutely no point in making a video, writing a book, or reporting "facts" if you do not make certain of your facts. There enough people in the world who don't really understand what they are talking about, without half-educating more.

  5. Even if the engine is sideways, atmospheric pressure could still push it. The reason for double action is that the steam (which is at a significantly higher pressure than atmospheric) is acting on every stroke. This difference is similar to the difference in power per size from a 4 stroke engine to a 2 stroke engine. Steam locomotive engines had at least two cylinders, meaning four power strokes per revolution. This is partly for power, but it is necessary for the engine to be self starting. This means that the engine is always in a power stroke.

  6. Centrifugal convergence is a thing. Sorry. General relativity is bs. Light isnt a particle. Electrons are silly, a negative charge? Its called a discharge. The universe is made up of centrifugal convergence and centripetal divergence. Its a electric universe yes. But electricity is only a hybrid of dielectricity and magnetism

  7. It's a nice video. But I'm sure someone had mentioned before. The gate position that changes where steam enters and exits should have the linkage rotated 90° counterclockwise

  8. Cool to see how may different steam engines are out there. Wonder how many times they fail before they got one to work.

  9. Awesome video. Seems like the cam lift and crankshaft stroke would have to have some kind of ratio. Do you know what that is ?
    If the crankshaft stroke was too long or too short it seems like the control valve wouldn't be open at the right time.

  10. Wasn't John Wilkinson that guy who shot Abraham Lincoln at the same time as he invented the iron cylinder, or whatever?

    Lets condense history? Why not.

  11. Its just so cool that one of your favorite channels makes a video about things your doing in school it just give me more motivation.

  12. i can make steam engines 86% efficient whether you believe it or not
    also knows as world higest efficient engine

    (2 way pistan engine)

  13. Can you do a video comparing the efficiency of automatic and manual cars? Its controversial and yet I couldn't find any useful content online.

  14. I really love your video, but should not speak so fast since understading technology takes time. Thanks.

  15. What if the heat from a car engine is used to power a steam engine, taking some load off the main engine to power things like the alternator and A/C.

  16. 2:46 i don’t understand, to me it seems that you made a mistake, you said you put the cylinder on its side and the atmosphere pressure can no longer force the piston back down? It is the pressure difference not the specific placement of the cylinder that cause it to retract. Please explain if you think you are right!

  17. Nice vid, but it doesn't actually explain how a steam engine works…I mean you quickly describe that most basic one, but then you don't go on the explain anything more modern.

  18. Yg saya tanyakan adalah dimana pembuangan gas yg sudah di manfaat kan kan itu di dorong setelah di dorong gas nya di buang Keman dan lubang output nya di mana sir

  19. how would atmospheric pressure push the piston back down if the other side of the beam is very heavy? there's no gear reduction

  20. Off-topic:
    The true wealth of a country is their people.
    The guy who invented the steam engine is the real wealth not how much natural resources your country have.

  21. Why do you say the valve is controlled by a cam when the diagram doesn’t show the use of a cam, do you have more diagrams with the details of the valve system and it’s relation to the piston and it’s control by the flywheel in particular? If so I would ejaculate in my pants at the possibility of building one of these.

  22. What you said about atmospheric pressure is wrong. You are confusing gravity with atmospheric pressure.

  23. What's with the stirling engine?
    More efficient, also invented in the early days, safer, the engine makes not so much nose, a lot of industry were running with stirling engine, …

  24. It would be smart to show how a steam power plant can operate at 800 deg C even though water boils at 100 deg C to produce steam.

  25. Thanks – lovely easy to read moving/diagram. The valve gear mechanism is very simple and very clever. I feel now I could build a working model of a steam engine which 5 minutes ago I couldn't.

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