Complex sentence: They first ventured into tractor production in a joint venture with Harry Ferguson in 1936 building the Ferguson-Brown, till Ferguson joined up with Henry Ford to allow his "Ferguson System" three-point linkage to be used on the Fordson N tractors.
Split into simpler sentences: They first ventured into tractor production in a joint project with Harry Ferguson in 1936 building the Ferguson-Brown tractor. Then Ferguson joined up with Henry Ford to allow his "Ferguson System" three-point linkage to be used on the Fordson N tractors.