Philosophy: When is a "lever" no longer a "lever"? - Page 10

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jpender
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#91: Post by jpender »

mrgnomer wrote:According to Britannica a Wankle is a type of internal combustion engine which uses an orbiting triangular rotor that functions as a piston. I almost got myself a Mazda RX8. It has a very interesting powerband.
I was imagining a lever machine that didn't use a piston. Suppose you had a lever press on a bag full of liquid and that provided the pressure. Would you just say, "oh, squishing a bag is a kind of piston"?

mrgnomer wrote:When performance is important what's under the hood isn't just interesting to know it can be defining.
But what is defining about a lever's performance? That is oddly missing from this thread. Jim hinted at it as he was most interested in taste, hence something intrinsic to what levers do.

But, ignoring the mechanics, what exactly defines a "lever shot"?

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mrgnomer
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#92: Post by mrgnomer »

Lever/piston machines offer preinfusion time and brew pressure control on extraction. There can be preinfusion pressure control and with springs there's a distinct pressure ramp down. All done by direct hydraulic piston compression. I don't know a whole lot yet but from what I'm understanding compressing a not so compressible fluid like water with a linear moving piston is very direct, responsive and flexible. Ideal for espresso extraction.
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donn
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#93: Post by donn »

jpender wrote:I was imagining a lever machine that didn't use a piston. Suppose you had a lever press on a bag full of liquid and that provided the pressure. Would you just say, "oh, squishing a bag is a kind of piston"?
Sure would. Apply force on the top, exert force at the bottom ... the notion of a fluid piston doesn't give me any trouble.

Liquid fluid, that is - a gas piston would introduce some novel properties. Might even be the next big thing. Imagine a gas piston - driven by an air compressing pump. There'd be a solid element at the business end of the piston, naturally. Could anything about that design possibly make you say "lever machine"?

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zix
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#94: Post by zix »

Didn't you just describe the Aeropress, @donn?
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donn
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#95: Post by donn »

No, but maybe the Handpresso.

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baldheadracing
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#96: Post by baldheadracing replying to donn »

FWIW, the Handpresso with the optional "intenso" basket delivers a spring lever pressure profile. (The regular basket is tuned for coarser moka pot grinds.)
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jpender
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#97: Post by jpender »

donn wrote:Liquid fluid, that is - a gas piston would introduce some novel properties.
What novel properties?

donn
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#98: Post by donn replying to jpender »

A compressible buffer between the input and output forces, AKA shock absorber. That doesn't have to make a difference, I'm just saying in principle it has the potential to.

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Jake_G
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#99: Post by Jake_G »

Isn't that what the small amount of air trapped beneath the piston does in this clearly unclassifiable group of machines we currently choose to call lever machines?
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drgary
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#100: Post by drgary »

Lever machines and people who know them when they see them.



Left to right: Francesco Soriano, Francesco Ceccarelli, Ryan Lee (IamOiman)

Not a lever machine. It's called a self-operating napkin, but I think it's a hat.



An image of a Rube Goldberg device that uses some levers https://en.wikipedia.org/wiki/Rube_Goldberg_machine
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