This workshop service manual covers the JCB JS115 Auto Tier 3, a robust tracked excavator designed for demanding construction and earthmoving applications. Built with JCB's renowned engineering quality, this model offers exceptional reliability and performance, featuring a powerful diesel engine meeting Tier 3 emission standards and a hydrostatic transmission for precise control. Its substantial operating weight of approximately 11,500 kg (25,353 lbs) underscores its capability in heavy-duty tasks. This manual is specifically for units within the serial number range 1703500 to 1703599. The purpose of this official factory service repair manual is to provide comprehensive guidance for the maintenance, repair, and servicing of the JCB JS115 Auto Tier 3. It details essential procedures, including lubrication schedules, fluid capacities, and service intervals for critical components like the engine and hydraulic system. Technical specifications, troubleshooting information, and safety guidelines are also included, ensuring that owners, mechanics, and technicians have the necessary knowledge to keep the equipment operating efficiently and safely.