This page has pictures of the cleaning up / restoration of a 1920's ATCO standard including information on electrolosis rust removal, which seems to work quite well.
The Rust Removal Setup, on the left the variac for getting 12V at a high current, in the middle a AVO so as to tell the current voltage and on the right a pair of high power selenium rectifiers.
To do electrolosis rust removal first a container is filled with water and a little washing powder is added to make it conduct electricity. Once this is done the positive is connected to electrodes made of iron or steel around the object and the object connected to the negative. A voltage of about 12 volts is then applied, upto 25 works but at 20 after a few hours its steaming (NOT recommended) especially for plastic containers. Here a gear can be seen being cleaned, you wudnt think it ! On the right the tin after being used for cleaning can be seen.
I didnt believe this method would work at all when I first went about it so I tried it on a gear, here all the gears can be seen when rusty, quite a mess and thats after a quick wirebrush.
After a day in the solution and a quick wirebrush this is what one of the gears looks like, quite an improvement considering.
And the gears painted.
Here the cleaning of the fan can be seen.
Here some other parts can be seen painted (primed ready for painting)
Here the clutch can be seen assembled on the driveshaft.
A 3d model of the clutch exploded.
The clutch semi assembled.