The frame is a parallelogram with the connecting links "mortised" into the shank and secondary jaw; the teeth face each other.
Clinch secured parallel Canadian patent CA-5,874 on March 24, 1876.
The U.S. patent date appears on an ELLRICH GRIP parallelogram pipe wrench. Its connecting links are "outside" the shank and secondary jaw as shown in the July 12, 1887 Philips patent (no. 366,246).