This manual covers the Allis-Chalmers B-12 Tractor, a versatile and reliable piece of agricultural machinery. As part of the Allis-Chalmers compact tractor line, the B-12 is known for its utility and was likely produced during a period of significant development in compact agricultural equipment. This tractor features a 3-speed manual transmission, a hydrostatic drive unit, and a two-speed pulley, offering a range of operational capabilities for various tasks. Its robust engineering ensures dependable performance for owners and operators. This comprehensive service and repair manual, along with its accompanying parts catalog, provides factory-level detail for maintenance, service, and part replacement of the Allis-Chalmers B-12 Tractor and its attachments. It includes detailed instructions, diagrams, exploded views, and manufacturer specifications covering engine systems, tractor systems, powertrain, hydrostatic drive, and electrical systems. The manual is designed to assist owners, operators, and mechanics in performing tune-ups, regular maintenance, adjustments, and complex repairs, ensuring the longevity and optimal performance of the tractor.