I'm fixing up an old tandem, and the cup-and-cone bottom bracket at the front sounds very gritty, so I picked up my c-spanner and applied it to the lockring. With a bit of effort, left cup and lockring both rotated together. Not hugely surprising that they're stuck together - both bits are quite old and grimy. But then I noticed that the right cup was rotating as well - as if it were rigidly attached to the left. The entire set (two cups and lockring) won't easily rotate more that about 20 degrees,and I didn't want to push any harder. How can this happen - aren't cups meant to be separate? Will I damage it if I keep rotating it? How should I unscrew it?
Some more details: The tandem is a 1940s Claud Butler - spec here: http://www.nkilgariff.com/CBcats/Cat_40/CB15.jpg. The bracket is inside an eccentric casing. I can't shift this at all, so I don't know how it's all connected inside. BB make is Bayliss-Wiley.
Photos are here: http://www.flickr.com/photos/88429902@N04/