The Rotary Tiller: Blades That Cut the Soil in Slices

A plough and harrow need several passes and a heavy tractor to pull them, and the wheels pack the soil they have just loosened. A rotary tiller drives its blades round from the engine: they chop down into the soil in slices, throw it back against a hood and leave it loose in one pass — and because the blades push backwards, they help drive the machine forwards instead of dragging on it. Arthur Clifford Howard began experimenting with rotary tillage on his father's farm at Gilgandra, New South Wales, in 1912, found that the ground could be tilled without packing it, and settled on L-shaped blades on widely spaced flanges on a small rotor. He patented a design with an internal combustion engine in 1920, and in 1922 formed Austral Auto Cultivators, later Howard Auto Cultivators. This rung plots the blade paths, works out the bite length that sets the tilth, and builds a drill-driven rotor to check it in sand.