Complex sentence: The rollers are larger than the cage so as the spindle spins the dies are pushed out to ride on the cage, as the dies cross over the rollers they push the dies together because of their larger size.
Split into simpler sentences: The rollers are larger than the cage so as the spindle spins the dies are pushed out to ride on the cage. As the dies cross over the rollers they push the dies together because of their larger size.