Identification of a Conti Princess with volumetric mechanism

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#1: Post by tebokkel »

Hi all,

Just kilometers from where it was produced - in Nice - I found a Conti Princess:

At least, that's what I think it is. It doesn't have a lever, but a volumetric mechanism that works on water pressure. Turn knob to set volume, push knob to lock a lever and start the flow and wait for you coffee(s). When the set volume is reached, the rod is release and the flow stops. See the movie I included (1:30).
The mechanism in detail:

One espresso:

Two lungos:

It is produced after 1965, as it has a Monaco address. The machine looks completely original and is gas operated, although the fitting for a light is present (no wiring though).

So... couple of questions:
- Is this a Princess?
- Are there more of these mechanisms (other Contis or other brands?)
- How is the pressure set on these (gas-)machines?
- Is the white stuff in the hood and the leftovers on the gas cover (see photo) possibly asbestos? (If not, what is it??)

White stuff on the (upside down) hood:

White gunk on the gas cover:

Looking forward to restoring this beauty.. :D


#2: Post by tebokkel »

BTW, this is the one and only thing I could find that resembles:
And it's also a Conti..

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#3: Post by jmc »

Yes, It is a Princess.

This is mine, unfortunately still waiting reassembly.

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#4: Post by Paul_Pratt »

That is a fine looking machine!

It should be a hydraulic group. It uses mains water pressure to brew the coffee - the mains pressure gets multiplied by the hydraulic chamber. They usually multiply the incoming water pressure by a factor of around x 3 and as such waste A LOT of water. Typically to brew a shot you will waste around 1L of water down the drain as the main chamber drains and fills when it completes 1 cycle.

They are very complicated to work on but extremely rewarding. I have some hydraulic machines and have restored them for other people. The closest one I have used to yours would be the Cimbali hydraulic. You can see it working here: ... =cafelatco

I just finished a rare Cafina machine from 1960 last week. Cafina is the fully-auto Swiss brand but they also have semi-autos. I've been using that as my daily driver for over a week now and it is great. ... =cafelatco

And the most interesting is a La Marzocco Poker machine that does not use water for power, but powers the hydraulic system using steam from the main boiler. Very clever. ... =cafelatco

They are fun. I have others like Rancilio's but no videos of them working.


#5: Post by boost »

That is indeed a Princess although I never seen one with that hydraulic group. It is really fascinating that lever machine of the 50-60s has pretty much same basic design but the hydraulic ones are wildly different and much rarer.
I think you can easily convert this to electric since the heating element from modern Conti should still fit.

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#6: Post by drgary »

So, Paul, listening to your explanation on the last video, steam pressure drives a piston to mimic a spring lever. How do the hydraulic machines without a piston keep the brew path cool enough to pull a decent shot?

What I WOULD do for a good cup of coffee!

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#7: Post by Paul_Pratt » replying to drgary »

All hydraulic machines are lever machines, use lever groups but generally without a spring and they use a different top section that bolts onto the standard lever group casting. The top section houses the hydraulic piston that generates the "9 bar".

Since they all use the same lever group casting, they have dipper tubes or HX just as some lever groups do for the brew water. The water that powers the hydraulic system just comes straight from the mains supply and is separate from the brew water circuit.

In general they use over 1L of water to power the hydraulic piston 1 cycle for your 2-3 oz espresso.

The La Marzocco poker was different in that it used the steam boiler steam to power the hydraulic piston up and down and rather than water going down the drain, steam would exit the machine! To keep up with service, it used a huge steam boiler and high power 3PH elements.

They are fascinating machines, no very eco friendly though. But with a bit of nous you could power the hydraulic system with air from a compressor or find a way to recirculate the water used for the hydraulic system.

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#8: Post by drgary »

Fascinating! Thank you for explaining that, Paul.

What I WOULD do for a good cup of coffee!