Building instructions for a Lego steam engine

For more information on this "steam" engine that runs on vacuum cleaner power, visit the main steam engine page.

Note that this model is constructed with old school Lego Technic. You can probably use ideas of this design to build your own engine with the newer generation of Lego Technic parts.

End result

Here's a picture of the final engine:

Step 1

We start with building one cylinder and its piston. For the (upside-down) top of the cylinder we require

2 x Plate 1 x 1 Round
2 x Plate 1 x 4
1 x Technic Plate 2 x 4 with Holes

Close the two outer holes of the 2 x 4 plate with the round 1 x 1 plates. As such, no air will escape here when pressure is applied to the piston.

Step 2

Now we add layers to create a box of blocks representing the cylinder. In the bottom and top layer, we leave an open hole, for air (steam) to go in and out of the cylinder.

1 x Brick 1 x 2
3 x Brick 2 x 2 Corner

Step 3

While building the cylinder, we also build the piston. The piston is an axle, with a 2 x 2 plate attached to it with a bush. I have used the (newer) black bushes, which hold a bit tighter than the grey ones.

1 x Technic Axle 8
1 x Technic Bush

Step 4

1 x Plate 2 x 2

Step 5

And we continue adding layers ...

2 x Brick 1 x 2
2 x Brick 1 x 4

Step 6

The technic bricks will serve as the cylinder's pivoting points.

2 x Brick 1 x 4
2 x Technic Brick 1 x 2 with Hole

Step 7

More layers ...

2 x Brick 1 x 2
2 x Brick 1 x 4

Step 8

Make sure that the piston can easily move up and down the cylinder.

1 x Brick 1 x 2
3 x Brick 2 x 2 Corner

Step 9

Finally, we close the cylinder with a lid.

1 x Plate 4 x 4

Step 10

We can now start with some of the framework for the engine

1 x Technic Axle Pin
1 x Technic Brick 1 x 16 with Holes
1 x Technic Pin

Step 11

The framework also supports the crankshaft of the engine.

1 x Technic Axle 3
2 x Technic Bush 1/2 Smooth
1 x Technic Liftarm 1 x 3

Step 12

1 x Technic Bush 1/2 Smooth
1 x Technic Connector

Step 13

1 x Technic Axle 6
1 x Technic Bush 1/2 Smooth
1 x Technic Liftarm 1 x 3

Step 14

Connect the next brick to the other side of the cylinder with a pin.

1 x Technic Brick 1 x 16 with Holes
2 x Technic Bush
1 x Technic Pin

Step 15

1 x Technic Brick 1 x 16 with Holes
1 x Technic Pin

Step 16

The plate and brick in the following step almost finalizes the air inlet of the engine (we need to top it off, which happens near the end). With your model, you can see how the cylinder's inlets align with (two half) holes in the long Technic brick, as it rocks up and down while rotating the crankshaft.

1 x Brick 1 x 2
1 x Plate 4 x 10

Step 17

1 x Technic Axle 3
2 x Technic Bush 1/2 Smooth
1 x Technic Liftarm 1 x 3

We're halfway through. Now, we create a second cylinder, in similarity with the first. This cylinder is a mirrored version of the first. Make sure to put the inlets of the cylinder on the mirrored side.

Step 18

6 x Brick 1 x 2
6 x Brick 1 x 4
6 x Brick 2 x 2 Corner
2 x Plate 1 x 1 Round
2 x Plate 1 x 4
1 x Plate 2 x 2
1 x Plate 4 x 4
1 x Technic Axle 8
2 x Technic Brick 1 x 2 with Hole
1 x Technic Bush
1 x Technic Connector
1 x Technic Plate 2 x 4 with Holes

Step 19

Finish up the crankshaft.

1 x Technic Axle 8
2 x Technic Bush 1/2 Smooth
1 x Technic Liftarm 1 x 3

Step 20

1 x Technic Brick 1 x 16 with Holes
1 x Technic Pin

Step 21

Now, we finish the framework.

2 x Plate 2 x 2 Corner
2 x Technic Brick 1 x 6 with Holes

Step 22

And we close the engine's air inlet

2 x Plate 2 x 2 Corner
1 x Plate 4 x 10

Step 23

More strengthening of the framework.

4 x Plate 1 x 4
2 x Plate 1 x 6
1 x Technic Brick 1 x 2 with Hole
2 x Technic Brick 1 x 4 with Holes

Step 24

Finally, we add a flywheel to the axle of the engine. Just use the biggest wheels you have.

2 x Tyre 81.6 x 15 Motorcycle
2 x Wheel 81.6 x 15 Motorcycle

Finished!

You are now ready to roll out your engine. To run the engine, grab the nearest vacuum cleaner, turn it on, and suck air through the machine by holding the vacuum cleaner's inlet to the air inlet of the engine.

Have fun!