Schematics of the Gaggia Achille

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#1: Post by gammeltoft »

Dear all,

Following much discussion regarding the Gaggia Achille lever machine, I've finally found a proper parts diagram. ... 0rev00.pdf

Two of the main controversies have been:

1) Whether this a HX machine - indeed a novelty for a lever machine

2) Whether the largish grouphead has a themosyphon (which would make sense if it is a HX).

The exploded parts diagram is not super clear, and I hope the more technically knowledged will comment. From the drawing it seems to me that is in fact a HX machine, sporting a short heat exchanger from the top down to the group head. However, the HE loop seems very short and while it makes sense that gravity will water from the basin on top down to the group, a good part of this loop must be over the water line in the main boiler. Would this work given the slower heat transfer from air (though moist!) compared to water?

Otherwise there seems to be two exits from the boiler to the group. This certainly speaks in favor of the thermosyphon that a Uk salesman long ago told me was the reason for the large group.

Lastly, the piston assembly looks as if its detachable from underneath, similar to the Cremina 2002 construction.

I continue to be intrigued by this machine - I'd love to try one out!




gammeltoft (original poster)

#2: Post by gammeltoft (original poster) »

Hi again,

I better correct myself, before someone else does. Dan just commented on the schematic and on closer inspection it does look as if the water feed from the reservoir (parts 20-21) goes directly to the group cylinder outside the boiler. If you look at the boiler, it seems there is only one entry point on top. Is it possible that the cold water from the reservoir is heated somewhere in the group or its connection to the boiler??

I'm really confused now - can someone with more engineering knowledge than me please help us out?



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#3: Post by another_jim »

I'm no engineer either; but it looks like Gaggia has done something really clever -- they've made the cylinder into the heat exchanger! The connection to the boiler is below water level, and it looks like it leads to a water jacket for the cylinder. The top part of the jacket may be steam. In any case, the design seems to have the group run really hot, and heat the cold water inside the cylinder.

What isn't clear to me is the timing. In idle, the piston is down. Suppose the water fills the cylinder over the piston, and valving transfers it underneath as the piston is raised. Then shots from idle would be overheated as in all HX machines. If the water stays out until the piston is raised, no warming flush is needed. In either case, it seems one raises the lever, then can wait for the temperature to rise to where one desires, since the water will heat up at this point. The reservoir is over the boiler, so the feed water will be quite hot in any case, and the wait shouldn't be long.

It seems it would be no big task to mount a surface contact TC somewhere inside the decorative cladding that will correlate with the shot temperatures.

If it really operates this way, it could be a very workable machine.