Well, consider what we call a squirrel cage, than take 2pcs, overhung and stuck in to each other.....
Rotating 300RPM each direction, you be careful when balancing as some not so far back was informed upon by reality.
Some picture a bit down, not so good but this design is almost vanished in history,
find here a clearer sketch:
So entering steam in the center and having 2 overhung rotors, stucked inside each other, that for balancing act as 1 unit almost despite they rotoate opposite directions......
In summary it makes the design to avoid resonance at 3000RPM and being a bit careful when adding weights. It do have a eddy probe in the steam to monitor
the bending and system clearance and when that die due to the environment operation is more difficult....... Clearance is 0.1mm or less on all stages, consider producing such things in the early 1900 when they started. I am still impressed and naturally as they were made in the town where I was born it does add to that, they had a complete factory floor full with manual lathes and the computer was another floor full with people operating adding machines to do the calculations and since there was no ready made material to order from stock a full material lab with funny machines testing materials did complete the scenery. I saw the material lab when having summer job in the lab but it's long gone now and I never saw the calculation room it was already gone but the workshop was still operating at that time, now it is a office space. Inventor and in some way developer Mr. Ljungström died destitute I think the term is 1960 after a total of like 122 patents and I had some problems finding a description that did make a view of the workings understandable so it is slowly sinking down in the mud of history in only like 100 years.....
I still think it is a beautiful design. I might 3D print one then it will be around another few years.
I found this describing the upgrade I didn't know of before that include some pictures, https://www.yumpu.com/en/document/view/248935/han-hamer-sulzer-turbo-services-repairing-and-performing
Obviously info was lost on the design during the takeover frenzy so it was rebuilt, reverse engineered and later destroyed during balancing (no fingers of mine involved) and a rotor set was about 2M Euro some years ago.
So what people do to avoid patent and get a compact in theory 10% more efficient device.