Spiral-blade choppers, often called aerators or renovators, differ from conventional roller choppers in that they use small blades welded to the heavy drums in a staggered, spiral pattern around the drum rather than the long, longitudinally mounted blades. These choppers normally use two drums mounted on a frame similar to an offset disk, and they are equipped with rubber tires for transporting. Spiral-blade choppers are pulled by a crawler tractor or a four-wheel drive tractor with special tire protection. Drum diameters vary from 18 to 42 inches and they can be filled with water for extra weight. Width is 12 foot but options are available. Tractor horsepower requirements vary between 120 and 350 and depend on chopper size, weight, tree/shrub size, and type of terrain.
Spiral-blade choppers gained popularity in the 1990s, especially in brush-dominated landscapes, because of minimal vibration, effective top growth removal, soil fracturing, and the small basins formed in the soil to hold rainfall. The basins also provide a good seedbed (see chapters on Site Preparation). Because of the rubber tires, the units are easily transported from site to site. Blade wear can be a problem, and new blades are welded in place. These choppers should not be used on rocky ground. Gravelly and some sandy soils can cause excessive blade wear.