This Service Repair Workshop Manual provides comprehensive information for Allison Transmission 4000 Series Generation Controls Vocational Models, including the 4000 EVS, 4000 HS, 4000 MH, 4000 RDS, 4000 SP, 4000 TRV, 4500 EVS, 4500 HS, 4500 RDS, 4500 SP, 4700 EVS, 4700 RDS, 4700 SP, 4800 EVS, 4800 SP, B 500, T 425, T 450, and T 525. Designed for optimal performance and reliability, these automatic transmissions are engineered to meet demanding vocational applications. This manual serves as an essential resource for understanding and maintaining the advanced technology within these units. The purpose of this English-language manual is to guide both do-it-yourself enthusiasts and experienced mechanics through the complete repair and maintenance process. It covers a wide range of topics, including General Information, Preventive Maintenance, General Overhaul, Transmission Disassembly, Module Rebuild, Transmission Assembly, Wear Limits and Spring Data, and Customer Service. With detailed illustrations and step-by-step instructions, this manual is an inexpensive way to ensure your Allison Transmission continues to work properly, offering complete disassembly coverage for thorough servicing.