This page is quite graphic intensive. So those of you still on 33kbps modems, please be patient.
If 700 rpm isn't impressive enough for you, then check out Mecevan's page.
With the lego rpm sensor, this fellow has been getting 2300 rpm
readings out of a similar engine to mine, running on suction from a
vacuum cleaner.
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This engine uses a 6x6 cylinder, and a 4x4 piston. I attribute the
higher speed with this design, it would seem that the added
displacement helps to offset the friction. It seems there's not the
same increase in friction in the larger size. (Some of my other engines
used 2x2 piston designs.)
Parts:
• 6x6 plate x 1 |
The cylinder head is a 6x6 plate
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Be sure to get this in the right spot. The valving/timing depends on the location of the ports.
Parts:
• 6x1 brick x 2
• 4x1 brick x 1
• 2x1 brick x 1
• 1x1 brick x 1 |
The cylinder head, shows top intake port
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Parts:
• 6x1 brick x 2
• 4x1 brick x 2 |
The cylinder head, second row
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Parts:
• 6x1 brick x 2
• 1x1 brick x 4 |
The cylinder head, third row
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The cylinder will 'rock' on these pivots. I used 2x1 blocks with the
pegs molded right into the side. You could also use a 2x1 block with a
hole, and then one of those grey pins, but the mechanism would be a
little more sloppy.
Parts:
• 2x1 brick with pegs x 2 |
Cylinder pivots
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Parts:
• 2x1 brick with holes x 2 |
Pivot blocks
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Use a 4x4 plate for the piston, and a gear snaps right into place in
the center. Then a 6-long shaft is used for the connecting rod.
Parts:
• 4x4 plate x 1
• 24 tooth gear x 1
• 6 length shaft x 1 |
Piston and rod assembly
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Piston fitted into cylinder
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Parts:
• 4x2 plate x 4 |
Base of cylinder
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Parts:
• 4x2 plate with holes x 1 |
Connecting rod exit gland
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Parts:
• 1x1 plate x 2 |
Plugging the extra holes
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Parts:
• wrist |
Wrist on connecting rod
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Parts:
• U figure it out |
First row of engine base
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Second row of engine base
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Engine base, not notches for pivot supports
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Parts:
• 2x2 inverted slant brick x 2 |
Engine base, pivot supports in place
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Parts:
• U figure it out |
Engine base, note notch for crankshaft bearings
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Parts:
• 2x1 brick with holes x 2
• Grey shaft collars x 2
• 8 length shaft x 1 |
Crankshaft and bearings in place
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Parts:
• 40 tooth gear x 1
• Large tire x 1 |
Bearings completed, crankwheel and flywheel in place
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Parts:
• 4x3 slant brick x 2
• 4x2 peak brick x 1 |
Cap on top of bearing assembly
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Parts:
• Grey pin x 1
(Attaches connecting rod wrist to crankwheel) |
Cylinder put into place
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| Ok, ok. I've been saying 'U figure it out' on some of these steps. That's
because there's an almost infinite number of possible ways to fill in
these parts. However, I will say this: Make sure you interlock the
parts with the layer below! In other words, cover the seams so that
there are as few 'stacked seams' as possible, so the structure is solid
and strong! (You expert LEGO builders out there know what I'm saying.) |
Final row on engine base
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Parts:
• 4x8 plate x 1 |
Steam chest bottom is 4x8 plate
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Parts:
• 4x1 brick x 4 |
Steam chest porting
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Parts:
• 4x8 plate x 1
As a final step it
may be necessary to put the engine on a nice flat surface and press
firmly around the engine base (and the cylinder before mounting it in
the engine base). This more thoroughly aligns the whole engine and
reduces binding. You may also need to do this periodically as well,
because the parts tend to work loose with running.
Also, a word
or two about running. The engine will not start at top (0°) or bottom
(180°) dead center. It needs to be slightly past one of these points
for the piston to apply sufficient starting torque. The engine may also
need a stronger starting blast of air than it does to keep it running.
There
seems to be something about the way a person blows, too. Some of my
friends are completely unable to run the engine; they just slobber all
over it. Others (including myself) know something about puckering up
and giving a good hard 'dry' blow into the engine. If all else fails,
and you are certain your engine spins freely, try running it backward
with a vacuum cleaner. This is how like to I like to run my double
acting twin cylinder engine. |
Completed engine!!
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