The very first LEGO pneumatic engine? |
| Two Engine Builders
ponder
whether LEGO meant us to build pneumatic engines like we have done. |
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| PK: Have you noticed the photo on the back of the box, upper left corner of
Technic set
8040? I built this, and after careful adjustment, it will continue to run
if you pump just right. Here is an example that shows someone at Lego was
thinking of converting linear motion to rotary. |
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| CS: Unfortunately I don't have the box. Maybe you can send me a picture of
the box and the device you build. I am most interested in this hint that
the LEGO people did think about linear to rotary motion conversion using pneumatics. In all their models, the pneumatics are only used for
pushing, lifting and grabbing. |
I have always asked the question whether the LEGO people ever thought of
using their pneumatics to build engines such as we have done. Because when we actually build, we find that the parts fit in perfectly even
though we may have to add a plate to get the height right. And when we
get the timing correct, the engine runs smoothly. |
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I always wonder why LEGO never put out instructions for building the pneumatic engines.
So maybe the conclusion is, they never thought of it! And that's why there are people like you and me ;-) |
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| PK: Here are 2 photos of the box. I will need to rebuild the model. I will send a
photo of it when I have it done. I am still struggling with the picture
quality. I hope that taking photos of the actual model will help clear things up. |
| The photo here shows no valves or the idea that an air tank might be used etc. |
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CS: Very interesting, there is no valve involved, the tubing from the hand
pump goes directly to the cylinder. Does it really work? If so, why wasn't it included in the 8040 building instructions? It looks simple
enough to build, even for a kid. And it will be proof that LEGO did think of linear to rotary conversion, a prelude to our pneumatic
engines. I guess only the LEGO people will know the truth. |
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| PK: True, there is nothing written and there have never been any instructions on engines.
I too, have wondered why. In 1998 I even wrote to Lego on this along with
some ideas and drawings for parts such as a spool valve which would have been ideal
for engine building. They seemed receptive too the ideas. Lego sent a reply
stating that as a matter of policy they do not accept unsolicited ideas. However they
wanted to make an exception in this case. I might still have their letter somewhere if you are interested. I have never seen anything else come of it. |
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| CS: Yes, they don't seem too happy to get suggestions from amateurs like us.
At one stage interest in pneumatics was on the verge of dying out as
the Technic pneumatics sets had nothing much to offer besides lifting, pushing and grabbing. |
| There was even worry that they were
going to discontinue the pneumatics. There has
been no Technic pneumatics set after the 8462 Tow Truck. But now I believe there has been
a renewed interest in pneumatics especially building pneumatic engines
and using them with the RCX. |
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| PK: Here are some closer photos of my rendition of the model on box 8040. When I saw
it I had to know if it works. The answer is YES. It is a very simple thing to build. You
only need to make sure the crank is at bottom dead center and the pump all the
way up when you connect both ends of the tube. The real trick is pumping in
harmony with the machine as it runs. My son is always eager to try this. |
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CS: Thanks, I will try it out. So is this also an engine? |
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PK: Good question. The best, most general definition of "engine" seems to be a device that
converts energy into work. I think it is merely a compound machine. It is only transmitting the
mechanical motion we put into it. |
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CS: I have built the device on the box of 8040. I hope
to send you pictures, too. Unfortunately it only work in spurts. I'm sure I built it right. But it will not run continuously even with a heavier "flywheel". |
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I think the reason is there is too much leakage from the pneumatics. It ought to work if the pump and cylinder and tubing were completely sealed. It depends on both compression and suction strokes. |
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PK: I have not been able to run it continuously for more than a minute. It does build speed on its own if I pump right. But then I always seem to mess up, pump out of time, and it stops quickly. The only thing I
can suggest is make sure the tube connecting the pump and cylinder is as short as possible to reduce the buffered effect caused by compressible air. You could try replacing the pump with an extra long cylinder to increase the amount of compression. Or, you could use the long cylinder and connect the tubing with the long cylinder all the way down and the cylinder on the crank all the way up to increase the amount of vacuum. Either way you will need to push down and pull it up while it is running. I tend to do that anyway even with the spring loaded pump. |
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CS: So I will not regard it as an engine which in my opinion must be able to run continuously as long as compressed air is supplied. |
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I can now understand why it was not included in the actual building
plans for the 8040 set. It was put on the cover just as a possibility of
the things you could built but not guaranteed to work. In the building
plans, the models must work otherwise the kids will be disappointed and
the parents would complain and maybe stop buying more LEGO! |
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So it would appear the LEGO people never really did think of using the
pneumatics to build the engines with proper valve gear like you and I
have done. |
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The only Technic pneumatics set that had some sort of automatic pneumatic action was the 8868 alternate model. |
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PK: Agreed. The air inside the tube is merely a component. It moves to and
fro just like any other part of this machine. But when you asked "is this
still an engine?" I started to think about Thomas Newcomen.
If it is true that he may have built engines of the over head beam
type, but with hand operated valves before 1712 then could
these be considered a true engine?
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Here is what ELEMENTS of STEAM and GAS POWER ENGINEERING copyright 1924 by the McGraw-Hill Book Company, Inc. has to say on the description of a steam engine...
"A steam engine is a motor which utilizes the energy of steam. It consists essentially of a piston and cylinder with valves to admit and to exhaust the steam, a governor for regulating the speed, some lubricating system for reducing friction, and stuffing boxes for preventing steam leakage." In the case of Newcomen a person operating the valves would have been an integral part of this machine. They would have served as the valve gear and governor. Anyway, just
thinking
:-)
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And now, it's over to you...
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Here are pictures
to help you build the model and then you can decide for yourself
whether this was truly the first LEGO pneumatic engine.
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Note: This model was built using parts from the 8040 set. Make sure
the crank is at bottom dead center and the pump all the way up when
you connect both ends of the tube.
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