Originally Posted by Andrew R Stewart

Spoken with no understanding of action and reaction For the inner part/driver push enough against the axle it must be held by the same force in place, in the crank arm threads. So 10lbs of extracting force is needed it is born by the outer sleeve as well as the inner driver. Anything else and the driver wouldn't be able to push those 10 lbs of force, the driver would just push it's self away from the arm (which is what happens when a crank arm's extractor threads pull out/strip out). Andy (who stripped out an am today, ask and I'll tell).