Short answers, pulled from the story.
Hiram Moore built and patented the first combine harvester in 1835 in the United States. His machine was capable of reaping, threshing, and winnowing cereal grain in a single operation, and a full-scale version harvested over 50 acres by 1839.
The Holt Manufacturing Company of California produced the first self-propelled harvester in 1911. In 1923, the Gleaner Manufacturing Company in Kansas and the Sunshine Auto Header in Australia independently introduced self-propelled models with additional modern improvements.
Combine harvesters are used to harvest wheat, rice, oats, rye, barley, corn, sorghum, millet, soybeans, flax, sunflowers, and rapeseed, among other cultivated seeds. Specialized headers are used for different crops, including grain headers for wheat, corn headers for row crops, and sunflower headers for sunflowers.
The Association of Equipment Manufacturers classifies combines by rated metric horsepower, from Class 5 at under 280 PS to Class 10 at over 680 PS. Class 10 was recognized in 2013, and the largest class 10-plus machines now carry nearly 800 engine horsepower with headers up to 60 feet wide.
From 1984 to 2000, 695 major grain combine fires were reported to U.S. fire departments, with fires typically starting near the engine where dry crop debris accumulates or from failed bearings and gearboxes. Dragging chains to reduce static electricity was one prevention method tried, though the role of static in starting fires remains uncertain. Using synthetic greases instead of petroleum-based lubricants at chains, sprockets, and gearboxes also reduces friction and fire risk.
Rotary combines pass grain along a helical rotor to strip it from the stalk, replacing the older system of rasp bars on a cylinder and concave surface. Sperry-New Holland introduced this design in 1975, representing a significant advance in how threshing is performed.