Non-Identical Twins

Oldmechthings · Jan 31, 2008

A while back Rowland Manufacturing Company in New Washington Ohio advertised model engine castings in just one issue of Home Shop Machinist magazine. Normally I do not buy castings, but these looked kind of unique and the price was reasonable. I believe it was a college student using his new computer design skills to design engines, same as POWDER KEG does. He had done a lot of work and had designs so the engine could be made into any kind of piston engine, gas, steam vacuum, etc. He sold the castings and plans separately. In order to maintain a little personal identity of my own I just ordered castings and made my own plan. When the castings arrived, in order to get more than my money's worth, I used the castings as patterns and poured a send set. One engine was fitted with an eccentric and a spool valve. The other with poppet valves. They are also timed to run on opposite directions.

Nothing spectacular, just more engines to look at.
Birk

cfellows · Jan 31, 2008

Hey Birk,

Nice looking engines. I'm particularly interested in the poppet valve engine. If you don't mind sharing, do you have a cutaway sketch of the inlet valve and passage arrangement? I've always had a particularly keen interest in compressed air engines with poppet valves, and because of the direction of air flow, they have their own peculiar set of design problems. Here is a picture of a design I have used:

Power Stroke

Exhaust Stroke

Chuck

Oldmechthings · Jan 31, 2008

Chuck
There is nothing fancy about my design. It is similar to a gas engine, no seals or anything. I just run the engines on low pressure air. If it were high pressure it would probably overide the spring and admit air to the cylinder all the time and the engine would not run. Does that answer your question?
Birk

Kactiguy · Jan 31, 2008

These are really nice little engines. Here is a video of them in action.
[ame]http://www.youtube.com/watch?v=BimqjOBtdX8[/ame]

cfellows · Jan 31, 2008

Oldmechthings said:
Chuck
There is nothing fancy about my design. It is similar to a gas engine, no seals or anything. I just run the engines on low pressure air. If it were high pressure it would probably overide the spring and admit air to the cylinder all the time and the engine would not run. Does that answer your question?
Birk

Yep, it makes things a lot simpler if the air supply is fed in from the back side of the valve. My efforts have always been directed at using the highest pressure air possible with a very short valve open time to more closely simulate the sound and action of an internal combustion engine. I also designed my valve so it would provide both intake and exhaust with only one push rod so it could be used in a Hit n Miss design. Unfortunately, I've not been very successful at designing a compressed air engine that works very well in a governor-controlled, hit n miss configuration.

Chuck