The matting faces of the coupler and knuckle were released from the original Jenney patents by their owner McConway & Torley back in the 1880s to the M.C.B (Master Car Builder) Association.. This allowed many other manufacturers to design and patent other methods of pivoting and locking and releasing the knuckle. By 1900 there were about 50 firms making variations of the M.C.B. design. In time most departed the business while McConway & Torley remains.

There was a message thread on the RyPN discussion Board back in 2006 that did not solve the problem of replacement parts for the Sharon couplers:
Sharon Coupler Knuckles? -- same link as in the post above.

Partway through the thread there was an inquiry about Irwin Car & Equipment. There was no response. But the firm still exists and serves primarily the mining and tunneling industries; it does have a page on its website about serving the heritage railroads and museums:
Atlas Car Parts, a unit of Irwin Car and Equipment, indicates that it has parts for the Sharon 10 and 10A couplers in full and 3/4 size.
http://www.irwincar.com/historic-railroad.php

Brian Norden