Rotary coupler with a specially configured pinhole

摘要

A rotary F coupler is described as having an improved pinhole design, wherein the backwall of the pinhole has a generally cylindrical, rectangularly shaped pin bearing surface which projects into the pinhole about three-quarters of an inch, compared to the conventional projection or crown of one-quarter of an inch, and in such a way as to prevent unduly high stress concentrations in the coupler shank caused by contact of the shank and pivot pin during vertical angling of the coupler.