Ford Motor Company Model 622 Self-Propelled Combine, circa 1970

For centuries, manufacturers have worked to perfect machinery that combines the three major steps of harvesting grain: reaping, or cutting the crop; threshing to loosen the grain from the chaff; and disposing of the straw while retaining the grain. Ford introduced its Model 622 combine around 1970. One selling feature? It took "only minutes" to change out the head for harvesting grain or corn.