Small Engines and Stuff

[Dave R]

Here's a little boxer engine intended to run on compressed air. For reference, the large gear is about 50mm dia.

Like usual I haven't added screws

[Mike Amos]

Pretty sharp, does it have a scavenge system for exhaust into a lower pressure reservoir, a la steam engines?

[Dave R]

Thanks. No scavenger system for the exhaust. It's just dumped out into the room. On the other hand it's only compressed air going in.

[Mike Amos]

Got it, if you can scavenge the exhaust air it can make the process more efficient, hence the three cycle steam engines. At least if I understood Fred anyway.

[Dave R]

A compound steam engine directs the exhaust steam from the first cylinder (smallest one) into the next cylinder which is larger. In the case of a triple expansion engine, a third cylinder (largest of the three) gets the steam from the second cylinder. This works because the steam still has energy to expand after the first and second cylinders. It does require the cylinders get progressively larger.