Ferguson-Brown produced the Model A Ferguson-Brown tractor incorporating a Ferguson-designed hydraulic three-point linkage hitch. Of the 1,356 produced 400 of the tractors were sold in Scandinavia. The early tractors were fitted with the Coventry Climax model E engine which was a descendant of the American Hercules engine as fitted to the prototype "Black tractor" later the engine manufacture was taken on by David Brown Ltd. who made a number of improvements such as a deeper sump, some of the earlier tractors suffered from oil starvation on hillside work. It has been narrowed down by surviving examples that the engine change from the Coventry Climax to the David Brown took place around tractors serial numbers 525 to 528. Harry Ferguson surmised that the tractor hitch was the key to having a better plough and designed a simpler tractor attachment for it.