Hi Grant, welcome to Outdoorking. The Greenfield site does not seem to explain how they protect the crankshaft from torsional overloads, so contacting them seems to be the best approach. The engine manufacturers tend to provide a keyway in the output shaft that is of suitable dimensions to allow the key to shear in emergencies, but it is usually a rectangular key, not a Woodruff key, so their efforts can be defeated by the shredder manufacturer providing an unusually long key. Only Greenfield can deal with your concerns.
