I'm surprised that no-one has mentioned the electrolysis method of rust removal for iron and steel objects which can be immersed in water. The equipment called for is basic - a plastic tub of sufficient size, some 'rebar' steel bar for electrodes, a 12V battery charger, water, and washing soda. It's been extensively covered on internet and is especially useful for de-rusing irrregular shaped objects, which other methods such as wire brushes can't access.
A couple of youtube examples are here, though the second one calls for much higher current than a battery charger could provide:
https://www.youtube.com/watch?v=qi8qIxK4IlA
https://www.youtube.com/watch?v=HN590K81D5c
I haven't tried the method myself - I've only fully stripped down and de-rusted one chassis - an Ekco AC77. I removed all the components, used a small belt sander (AKA 'electric file') to remove the rust, then treated the chassis with Jenolite. To finish the chassis I sprayed it with acid etch primer, and Halfords brand Ford 'Dove Grey' gloss, which Gary Tempest advised me was a good match for 1930s Ekco chassis, as indeed it proved to be.
First pic below shows the rusted chassis with all components removed.
Second pic shows the chassis half de-rusted with the electric file.
Third pic is after treatment with Jenolite.
Fourth pic is after re-spray.
Last pic is after main components had been re-fitted.
Hope that's of interest.