This manual covers the Allis-Chalmers 616, 620, and 720 Tractor models, produced during the late 1970s to mid-1980s. These tractors represent a robust line of utility vehicles from a manufacturer with a long heritage in agricultural machinery. Designed for a variety of tasks, they combine dependable engineering with practical functionality, making them valuable assets for farm work and general property maintenance. The models are known for their straightforward design, emphasizing reliability and ease of operation, which has contributed to their enduring utility. This comprehensive Service Repair Manual provides essential information for the maintenance and repair of your Allis-Chalmers tractor. It details engine service, transmission and hydraulic system repairs, electrical system diagnostics, and chassis and drivetrain components. The manual includes procedures for routine maintenance, component overhauls, adjustments, and disassembly/assembly, along with systematic troubleshooting guides and detailed technical specifications. This resource is intended for tractor owners, farm mechanics, and repair shops, offering authoritative information to ensure the optimal performance and longevity of your equipment.