Philosophy: When is a "lever" no longer a "lever"?

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#1: Post by Jeff »

That is a question I've been pondering for a while and resurfaced by the great thread How Modern Hybrid Lever Espresso Machines Work that I don't want to distract or diminish in its value.

When does a lever machine cease being a lever machine and just become a pressure-profiled pump machine?

One definition might be when the motive force is applied only with manual pressure or with a cocked spring and there are no other modifications of the extraction pressure.

That gets messy as a definition when you start adding in air-escape valves or pressure-dump valves.

It also rules out the Nurri Leva, with its "Servo Assisted Lever", as well as the La Marzocco Leva.

If the Leva is a lever machine, what about the Meticulous? Is that a lever machine because there is force acting through a lever to drive a piston down a cylinder?

If that is a lever machine, do you rule out the Unica because its piston is belt-driven?

I have some vague opinions, but no answers. I'm curious about yours.
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#2: Post by another_jim »

When I first reviewed the Strega, I caught enough flak that I specifically stated that it was not a purist lever machine for experts, but a hybrid with wider appeal. By that time, it had already become clear that long preinfusion and declining pressure spring lever profiles were very good for lighter roasts. In particular, they made shots that tasted similar to how coffee tasted brewed, without the amplified bitters and acids, and diminished sweetness, of most regular pressure shots. The Strega and subsequent assisted lever and profiling machines made this available to everyone, not just those specializing in levers.

In evolutionary biology, there is a concept called "preadapation," when some feature that was useful in one minor context suddenly becomes the next big thing when the species evolves into new lives. Feathers, used by dinosaurs for insulation for tens of millions of yearrs, becoming useful for flying, is the standard example.

In espresso machines, we've had two very striking cases of preadapation. First, the spring lever profile as applied to lighter roasts. Second, the needle valve inthe E61, present in the patent design, and briefly used for flushing the group, suddenly getting a much more glorious second life as a pressure profiling controller.

So, when is a bird no longer a dinosaur?
Jim Schulman
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#3: Post by Honeycomb »

Maybe an over simplification, but I would tend to think of it using more of an Occam's Razor approach. If there is a lever used to drive a piston to create brew pressure, it is a lever machine. That provides a pretty hard line in the sand for what is and isn't a lever machine despite the varying degrees of automation/derivation.

That pawns some of the messy portion off of the top level classification and into subclassing them almost in a similar style as music genres. Sure, it's rock music, but is it classic rock, indie rock, alt rock, etc... Sure it's a lever, but is it a manual lever, modern hybrid lever, spring lever, etc... and that is where it gets a little more vague.

The meticulous would still get a pass since there is a class 1 lever tucked away in the housing, but with the above logic it gets some weird mile long name like an "Electronically Actuated Automated Lever".

Is something like the Vectis just a spring lever, or is it a modern spring lever because it has 58 mm and a joystick valve? At what point does modern transition to legacy?

So here we are... back to square one in the other thread of "What is a modern hybrid lever?"
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#4: Post by 51M0N »

another_jim wrote:So, when is a bird no longer a dinosaur?
Birds are (still) dinosaurs according to the modem classification. Not sure that information helps much on the lever front though.

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#5: Post by pizzaman383 »

I tend to think that the way the group is heated doesn't change the fact that if it has a lever, piston, and cylinder it is a lever espresso machine.

My reasoning is that the history of levers has been continuous search to find economical means of providing steam while producing reasonable brew water temperatures. The availability of cheap PIDs, various types of heating elements, and continued innovation has produced better methods of heat management.
LMWDP #551
“Taste every shot before adding milk!”


#6: Post by Primacog »

Keeping it simple, my own take is its a lever machine if the extraction pressure is provided by means of a lever mechanism of any sort. That would include the meticulous though for me the meticulous really is on the uttermost border of what a lever machine is.
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#7: Post by donn »

I'm not familiar with Meticulous, but the web page says "motorized piston." I infer that a sensible motor drive is going to use something like gear/pinion - not a lever? Otherwise I'm with you - lever means, you produce the brewing pressure by operating a lever that drives a piston.

It seems to me I have seen people refer to E61 as a "lever group", because there's some gimmick operated by a lever. That would be wrong. On the other hand, a pump is a pump, and to me a piston pump is a lever pump only if there's a lever. Perhaps I oversimplify.


#8: Post by Honeycomb »

I was pretty unfamiliar with the Meticulous brew method until this thread and assumed the "automatic lever" was just marketing jargon for the actuator driving a piston. It's definitely pushing the bounds of what a lever is, but sure enough it uses a lever for generating brew pressure. The linear actuator is housed in the rear and is pushing up on a linkage that has a fulcrum in the middle and a load on the opposite side.

Feels counterintuitive to call it a lever without seeing a big lever and handle sticking off of the front face. Definitely a fringe case of "what is a lever" with the way I view it, but it meets the dictionary definition of a lever mechanism.

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#9: Post by espressotime »

I use the definition of Reiss of Londinium Espressomachines.
He was spot on.
A machine that uses a pump to bring water in the group isn't a lever machine.
It is a pumpmachine that uses the lever as festive decoration. Therefore the only levermachine Londinium makes is the Vectis. The other ones are pumpmachines/hybrid machines.
And he is right. Since preinfusion is part of the extraction.
An espressomachine with a pump inside to me is a hybrid. Half pump,half lever.
Anything without a pump is a levermachine.

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#10: Post by pizzaman383 »

I think we need to differentiate the terms. Hybrid lever means uses a pump. Classic lever uses boiler or line pressure to fill the boiler. Lever means either.
LMWDP #551
“Taste every shot before adding milk!”