The Allis Chalmers D12 Tractor represents a robust piece of agricultural machinery, a product of a historically significant American manufacturer known for its quality and reliability. Produced generally from the mid-1950s through the early 1960s, the D12 is designed for a variety of farm and industrial tasks. Its engineering prioritizes durability and efficient operation, making it a valuable asset for mechanics and DIY individuals alike. This tractor embodies the practical innovation characteristic of its era, offering dependable performance for its intended applications. This comprehensive workshop service manual provides essential information for the maintenance and repair of the Allis Chalmers D12 Tractor. It covers a wide range of systems, including the engine, transmission, fuel, electrical, and hydraulic systems, with detailed procedures for overhaul, troubleshooting, adjustment, removal, installation, disassembly, and assembly. The manual also includes information on maintenance schedules, special tools, and factory specifications, all presented with clear explanations and detailed illustrations. Its purpose is to empower owners and technicians to effectively maintain their tractors, ensuring longevity and optimal performance through accurate adherence to service guidelines and safety protocols.