Sperry Rand Corporation - Sperry New Holland Division Catalog, "TR70 Twin Rotor Combine," 1977

Engineers designed the TR70 as a compact machine suitable for hilly terrain. The twin rotors (TR) shelled corn or threshed grain and moved it through the combine's body. Setting the rotors at an angle (axial) shortened the machine. Farmers changed the front-end attachment to harvest corn, beans, or wheat. Photographs and diagrams in this catalog helped explain additional features.