A former Sears, Roebuck & Co. clerk received an $8.5 million out-of-court settlement after a 20-year dispute with the retail giant over profits from a wrench he invented 25 years ago.

Peter Roberts, 44, of Red Bank, Tenn., on Friday settled a patent infringement case that said Sears had cheated him out of royalties from his push-button socket wrench, for which the company has earned an estimated $5 million, according to Kathy Gucfa, a spokeswoman for Sears.

Gucfa said Sears, which sold millions of socket wrenches between 1965 and 1977, paid Roberts $10,000 for rights to the patent. But Roberts, who said Sears told him the tool had only minor sales potential, later saw an elaborate display of the wrench in a Sears catalog and sought to rescind the agreement under which he sold the patent.

An appellate court overturned a federal jury`s 1982 decision that awarded Roberts $5 million and ordered a new trial after finding that Sears violated the patent, Gucfa said. The new trial was in its fifth day when the settlement was reached.