Single-piece crank locknut problem
 

Hi guys, I figure the knowledgeable folks here would be more helpful with a mechanical issue on my early 80s folding bike. I'd like to take out the one-piece crank to service the BB. It should be simply unscrewing the left-side locknut and then the rest. But there is a dust cap that turns with the crank, and this cap has a raised lip which prevents me from slipping a spanner squarely on the locknut. As a result, I couldn't get a good purchase on the locknut to work with it.

A socket wouldn't work either with the crank sticking out on the side, if I can even find a 1 1/8" socket to begin with. Has anyone dealt with this before? Or have a good idea what tool I can use? Thanks a lot!

Combination wrench (closed end), or careful use with water pump pliers (channel locks).

Remove the pedal and use the closed end of a combination wrench, which will probably also be angled too.

Pipe wrench.

Thanks Bill and Mos! I got a hold of a 1 1/8" box-end wrench and it did the trick.