Originally Posted by dddd

A couple of more things.

I advise riders of cotter-crank models to, if possible, leave the entire bottom bracket and crankset alone!
The bearing tension can be adjusted with the arms in place. The right cup tends never to loosen on factory-assembled bb's, but can be secured (if ever needed) with a thin wrench (and hammer), again with both arms left in place.

The bearings can be lubricated from outside, using the applicator tube on a can of aerosol lithium grease. Even a periodic oil-can drip will keep the original bottom bracket in good form for many years of normal use.

I mention all this because removing the cotters without damage is a real challenge that usually requires experience and the application of heat in conjunction with a press of some kind. Replacement cotters found today will not hold up to much riding, they are way too soft!!! Original cotters in the exact right diameter would have to be searched for and carefully selected, all of which makes lubricating the bearings in situ a good idea for most.