Is this anything?

[Captain Jerry]

I don't know why it starts out black, but its a video. Click on it!

David Letterman has a recurring segment on his show where he looks at stuff and wonders if its worth pursuing. This is a design that occurred to me and gave me some restless nights until I put it to the modeling process and worked out the geometry. I have always liked beam engines and grasshoppers particularly.

Putting it in motion with Alibre' has convinced me that it can be built and will operate without serious problem. It uses a two throw crank with 180° offset and because of the 90° relationship of the conrods, it is self starting and balanced.

I was about to start cutting metal when something happened to get me back on the Donkey. The Donkey is still top priority but this thing keeps tugging at me. I have a chunk of cast iron that I want to turn into a crosshead guide ala popcorn and I have a different approach to an elbow engine that I need to prove.

How do you stay focused on one project? I seem to be suffering from late onset ADD. I need a bigger shop, and maybe some minions.

Jerry

 

[cfellows]

Interesting looking engine. Even though the 90 degree offset of the connecting rods makes it self starting and more interesting I would think the sharp angle of the connecting rod relative to the piston movement would keep you from getting the best force transference to the crankshaft. Seems like that would put quite a lot of lateral force on the piston and piston rod.

Chuck

 

[Captain Jerry]

Interesting looking engine. Even though the 90 degree offset of the connecting rods makes it self starting and more interesting I would think the sharp angle of the connecting rod relative to the piston movement would keep you from getting the best force transference to the crankshaft. Seems like that would put quite a lot of lateral force on the piston and piston rod.

Chuck

The grasshopper linkage is a very robust straight line mechanism. The links are much larger and better oriented to absorb the lateral forces than the Watt linkage. The center of rotation of the beam is the pivot st the far end of the beam (approx) and if you draw a line from that point through the center of the shaft, you will see that the conrod is 90° to that line when the piston is at TDC or BDC. I agree that it looks a little strange but my engineering books don't really oppose strange!

Thanks for taking a look, Chuck. There may be plenty of good reasons why this isn't anything. Thoughts and opinions can only help to improve it.

Jerry

 

[AussieJimG]

Yes, it looks like just a couple of standard grasshopper linkages (I knew the linkage but didn't know it was called that).
And I agree with Chuck that the conrods should be vertical.

And don't worry about the ADD, it combines with memory loss to erase past mistakes, embarrassing moments and guilt feeling about half-completed jobs. ;D

Jim

 

[tel]

Can't possibly work - there are no valve linkages!

 

[zeeprogrammer]

How do you stay focused on one project? I seem to be suffering from late onset ADD. I need a bigger shop, and maybe some minions.
Jerry

I'd like to know too.

Minions would be good. But I'm a minion. Can minions have minions?

 

[tel]

Nah, minions can have bunions, but not ......

Waddya mean, minion anyway Carl? In your shop you are the CEO.

 

[AussieJimG]

What are the horizontal rods Tel, I thought they were the valve linkages. You can see that I dunno much about steam.

Jim

 

[steamer]

Hey Capt'n

It sure looks cool! Yes late onset ADD should be embraced...just don't grab or call it a minion.... ;D


Dave

 

[Captain Jerry]

Its worse than I thought. It seems to be a mix of OCD and ADD. I keep doing something over and over and over, but its different every time!

Tel

Since the conrod layout is irrational, the valve linkage and the valves are imaginary causing a great amount of uncertainty.

Jerry

 

[AussieJimG]

OCD? Is this something else I have forgotten? Or is it just Deja Vu all over again

Jim