Abstract: Leading edges of rotor-plates which carry the swing hammers of hammermills are protected from wear by removable caps, each secured by paired pin assemblies, each of which may be shifted axially to permit removal of the cap it normally secures. Each pin assembly includes a pair of tubular pins or pin portions which may be axially abutting one another, each assembly including at least one portion which is short enough to be removed (or moved axially to a position which permits removal of the cap). In the original form of the parent application, each assembly was totally countersunk within the cap, having heads at each end that were countersunk and having in each head the countersunk head or nut of a tie-bolt. In the form preferred at the time of filing this continuation-in-part application, the pair of tubular pivots forming each assembly is held in place by reliable friction resulting from the expanding force of split-spring-tubes forcefully squeezed substantially closed during insertion.