This manual covers the Allison Transmission 4000 Series, an automatic transmission family known for its robust engineering and reliability. Designed with Allison's 4th Generation Controls, this transmission offers advanced performance and efficiency. Optional features such as a power takeoff (PTO) and output retarder enhance its versatility for various demanding applications. The focus on major transmission components and sophisticated control systems ensures optimal operation across its intended uses. This Service Repair Factory Manual in English provides comprehensive guidance for maintaining and repairing the Allison Transmission 4000 Series. It includes detailed information on general operation, preventive maintenance, and overhaul procedures, covering transmission disassembly, module rebuild, and assembly. The manual features step-by-step instructions, part inspection guidelines, wear limits, and customer service information, supported by clear line drawings, cross-sectional views, and exploded views to illustrate correct procedures. This resource is designed to assist owners and technicians in performing effective maintenance and repairs, potentially leading to cost savings.