Lee is correct in his post above, and it is stated as such in the SCSW, but the reason I said "technically" is because a crane refers to a swinging mechanical apparatus, while a yoke is a stationary one. They do indeed both perform the same function on a revolver in that they tie the cylinder to the frame, so either is acceptable in my opinion, even though S&W uses the term yoke. It is probably a simple matter of them wanting to be different from their competition in their terminology.