International Harvester was formed in 1902 in Chicago through the merger of the McCormick Harvesting Machine Company and the Deering Harvester Company. The combined company became one of the leading manufacturers of farm machinery in the United States, and its name is still remembered today simply as Harvester.

Harvester is best known for its Farmall line of row-crop tractors, introduced in 1924, which grew into the Letter series and Number series, along with the smaller Cub tractor. These tractors were powered by four- and six-cylinder gasoline and diesel engines built for continuous farm use. The company also built construction equipment, including its Pay Line loaders. The agricultural side of the business was sold in 1985 and became Case IH, while the parent company was renamed Navistar in 1986.

The manuals on this page focus on Harvester tractors, agricultural engines, and vintage equipment. Typical coverage includes engine rebuild procedures, transmission service, electrical systems and wiring diagrams, torque specifications, diagnostic steps, and scheduled maintenance intervals for these agricultural machines.

Because many Harvester tractors have been in service for decades, having accurate factory-level documentation is especially important for diagnosing wear, sourcing correct parts, and following the original engine specifications rather than guesswork. This information is useful for DIY owners maintaining a Farmall or other Harvester tractor, independent repair shops that service older agricultural equipment, and restorers working to keep vintage Harvester machinery in running condition.