Maybe it is a bolt similar to a lug stud with a splined and/or tapered shaft. At the factory, as it would be tightened, the tighter it gets the spline and/or taper would lock into the hole. The design would have to assume they would never need be removed.
EDIT: I found what they are called, Ribbed Neck Carriage Bolt.
Last edited by FriedGreenTmater; 11/13/2011 7:32 PM.
