Really Interesting Model Air Powered Hit n Miss Engine (Old)

[cfellows]

Stumbled across this video today and it has really captured my attention.  It's a model hit n miss engine that runs on compressed air, and it really runs and sounds nice.

<a href="https://www.youtube.com/watch?v=Uc4y9p5TQ1w" target="_blank">http://www.youtube.com/watch?v=Uc4y9p5TQ1w</a>

It has two valves, inlet and exhaust, and both appear to be activated simultaneously by the governor.  Wish I could find more information on it.  Anybody have any prior knowledge or ideas on details?

Chuck

[Jasonb]

Really no different to the Jowitt popett valve engihe that I made a while ago except there is a rocker arm and bell crank in the valve linkages. Would be single acting eg air pushes the piston down and the momentum of the flywheel carries it back up which pushes the air out the exhaust.

Would be quite simple to replicate. Just need to work out the governor, I would have thought it is set to keep the inlet closed during the miss cycle otherwise you would waste air and then open the inlet as the speed slows. Exhaust is held open while missing so air can be sucked in and out by the piston movement.

[crueby]

That is brilliant! Would love to build a version of that, given plans. I found a reference to that company also being on Latta Road here in Greece (suburb of Rochester NY). Very little info otherwise.

[Jasonb]

Gas Version on Smokestak  and mention of the popett valve ones

https://www.smokstak.com/forum/showthread.php?t=122320

[cfellows]

Really no different to the Jowitt popett valve engihe that I made a while ago except there is a rocker arm and bell crank in the valve linkages. Would be single acting eg air pushes the piston down and the momentum of the flywheel carries it back up which pushes the air out the exhaust.

Would be quite simple to replicate. Just need to work out the governor, I would have thought it is set to keep the inlet closed during the miss cycle otherwise you would waste air and then open the inlet as the speed slows. Exhaust is held open while missing so air can be sucked in and out by the piston movement.

I believe from watching the video there is some overlap between the exhaust valve opening the inlet valve closing.  While perhaps not as efficient, this seems to be what makes the more interesting pop or sound of the engine "firing".

[cfellows]

Gas Version on Smokestak  and mention of the popett valve ones

https://www.smokstak.com/forum/showthread.php?t=122320

I just really like the sound of the firing cycle.  It's kind of what makes this engine so interesting.  I've always had some difficulty getting my compressed air engines to sound the way I want, particularly with the slave valve setup.

Chuck

[cfellows]

That is brilliant! Would love to build a version of that, given plans. I found a reference to that company also being on Latta Road here in Greece (suburb of Rochester NY). Very little info otherwise.

Yeah, this engine has really rekindled my interest in compressed air engines.  Gotta try to find more details!

Chuck

[b.lindsey]

That really does have a nice hit and miss sound to it Chuck. Hope you can fine more details on it.

Bilk

[90LX_Notch]

That really does have a nice hit and miss sound to it Chuck. Hope you can fine more details on it.

Bilk

Hey Bilk!  What did you do with Bill?

-Bob

[crueby]

That really does have a nice hit and miss sound to it Chuck. Hope you can fine more details on it.

Bilk

Hey Bilk!  What did you do with Bill?

-Bob

Uh-oh, Bill's shop gnomes have locked him in the closet and taken over his computer!

[Jasonb]

As there are two separate cams any overlap is taken care of by how the cams are timed in relation to each other and their duration.

As you say it certainly has the right sound to it.

You could send a comment to Gil via Youtube and see if he can take a few close up photos.

[cfellows]

As there are two separate cams any overlap is taken care of by how the cams are timed in relation to each other and their duration.

As you say it certainly has the right sound to it.

You could send a comment to Gil via Youtube and see if he can take a few close up photos.

I took your advice and sent him a request in my most pleading manner.  Even asked him if he were willing to sell it or trade for one of my engines.  He's still active on youtube as of 6 days ago, so I hope to hear back from him soon.

Chuck

[Jasonb]

He is very active on you-tube as he has such a large collection of engines, also usually does a video of teh major shows.

If you have time on your hands it is well worth a look through his you-tube channel.

[b.lindsey]

Oops, that's what I get for trying to type on the phone  . Fortunately the gnomes are still under control.

Bill

[cfellows]

I guess I'm being impatient, but I'm a little disappointed that I haven't heard anything back from Gil, the owner of the motor.  Doing a little design work today, I already have a horizontal single compressed air
engine that has all the inlet valve parts in place.  I should be able to add a governor mechanism pretty easily to activate the inlet push rod at lower RPM.  All I need then is to redo the head with a poppet exhaust valve assembly, a latching mechanism, a cam to drive it, and a mechanism for the inlet push rod to release the exhaust valve latch.

So, I'm going to continue to see what I can come up with.

Chuck

[Flyboy Jim]

Oops, that's what I get for trying to type on the phone  . Fortunately the gnomes are still under control.

Bill

That's not too bad on this forum Bill, but it might not be to good when selling something on Craigslist: "For Sale: Car..........just like new.......no problems at all...........never been wrecked. Signed Bilk

Bilk: https://www.merriam-webster.com/dictionary/bilk

 

[cfellows]

I'm going to have to change the governor/inlet valve arrangement since it works differently than a typical exhaust valve governor.  The difference is, that an exhaust valve governor holds the valve open during high speed which is accomplished by simply holding the push rod away from the cam.  When controlling the inlet valve, the mechanism must prevent the inlet valve from being opened during high speed so a simple latch won't work.  I think the motor we're discussing here uses a variation of the GE centrifugal governor which is similar to the governor used to advance timing in older car engine distributors.  The variation swings the entire eccentric to one side rather than just rotating (and advancing) the cam.

Here is a schematic of how I think the governor on this engine works.  Mechanical details and shapes need to be refined to fit in a reasonably small, circular envelope.



An eccentric is used for the cam and it swings on a swivel.  The arm with the weight centers the eccentric at higher speeds.  As the flywheel slows down, the spring pulls the eccentric off-center allowing it to swing against the push rod and open the intake valve.

I've also worked out a lever arrangement so the inlet push rod can release the exhaust push rod letting the exhaust valve close.  On my initial go around, I'm going to leave the slave valve in place and just concentrate on the inlet valve.

Hope all this makes sense.  If anyone has additional information on inertial governors, vs centrifugal, it might be an easier approach.

Chuck