Maytag and Mason proved to be inexperienced in the car-making business and the company gradually folded. Fred left the company in 1910 to focus on racing and engine designs in his shop in Des Moines. The Maytag-Mason partnership was dissolved in 1912 and its auto production ended the following year. Around 1910 Fred and Augie Duesenberg began work on their "walking beam" four-cylinder automobile and racing engine, which was later replaced by the Duesenberg straight-eight engine. The brothers shared the patents for both engines, which were filed in 1913 and renewed in 1918. In 1913, the Duesenbergs relocated to Saint Paul, Minnesota, where they continued to develop racing cars and automobile and marine engines. The two brothers contracted with Commodore James A. Pugh of Chicago, Illinois, to build a racing-boat engine and used the proceeds from the contract to further develop their racing business. In June 1913 the brothers also founded the Duesenberg Motor Company, Incorporated.