Advanced Hydraulics Inc. v. Otis Elevator Co‪.‬

CLARK, Associate Justice This appeal tests the validity of a summary judgment entered by the District Court on the ground of estoppel and laches in a patent infringement suit. It appears that a ""hydraulic elevator"" patent was applied for on February 16, 1951, by one C. A. Anderson, Jr. and was issued to him on August 4, 1953. In 1967 the patent was assigned to appellant, Advanced Hydraulics, Inc. (Advanced), and on June 30, 1967, counsel for Advanced sent out notices of infringement to some 15 companies operating in the field. One such notice, in the form of a letter, went to the president of appellee, Otis Elevator Company (Otis), and stated, inter alia: It has come to our attention that you are making and selling products which are an infringement of this patent... various models of fork lift trucks manufactured and sold by your Baker Division in Cleveland.