This manual pertains to the International Harvester 634 Series Tractors, a line of agricultural machinery known for its robust engineering and reliability. Produced likely between 1968 and 1975, these tractors represent a significant part of International Harvester's heritage in agricultural equipment. The 634 Series typically features a diesel engine from the BD Series, offering dependable power for a variety of farm tasks. Their design emphasizes durability and functionality, making them valuable assets for owners and operators. This compilation of service bulletins provides critical technical updates and solutions, enhancing the maintenance and repair capabilities for these vintage machines.

The purpose of this document is to serve as a comprehensive workshop supplement and compiled service bulletin book for all International 634 Vintage Series Tractors. It covers an extensive range of systems, including engine overhaul, drivetrain, hydraulics, chassis, steering, braking, and electrical systems. Detailed maintenance and repair procedures are provided, alongside troubleshooting guidance for common issues. This manual is designed to assist owners, mechanics, and technicians in effectively maintaining, diagnosing, and repairing these tractors, ensuring their continued operational efficiency and longevity. The information presented is crucial for preserving the performance and value of these classic International Harvester machines.