A self-propelled agricultural application machine includes a chassis which carries a storage tank for the material to be applied. The chassis has a central longitudinal beam from which at least a pair of wheels is suspended. A transversely-extending boom assembly is suspended from the longitudinal beam. An engine is located to one side of the longitudinal beam and has an output drive shaft connected through the longitudinal beam to hydraulic pumps. The narrow chassis allows steerable wheels to be positioned at tolerable track widths while permitting a large steering angle and thus small turning radii.