Hierarchies of synchronized and algebraic forests

A two-part separable, semi-unitized shaft seal for sealing between a housing bore and a relatively rotatable shaft extending through the bore and comprising a metal wear sleeve member and a sealing member assembled onto the wear sleeve member for shipping and installation of the seal as a unitized seal. However, when the housing and shaft are disassembled, the wear sleeve remains on the shaft and the sealing member remains with the housing, whereby each part can be examined and replaced, if necessary, without discarding the entire seal. The wear sleeve press-fits onto the shaft and the sealing member forms an elastomeric interference fit in the housing bore.