early 1970s: Agrati steel crank, broke at the spindle and cotter eyes; able to ride home with left pedal timing advanced relative to right.
early 1990s: 1970 Sugino Mighty Compe, broke across the pedal eye during an out-of-saddle climb; ouch!
today: early 1990s Campag. Veloce, crack developing across the end of the spindle eye, parallel to the spindle (pictures to follow)
The Capo once again has an early 1970s Nervar Star crankset, which doesn't look as nice, but at least is much closer to period-correct.