This comprehensive Allison Transmission HT 750DR Preventive Maintenance Manual is your essential guide to ensuring the safe and reliable operation of your heavy-duty equipment. It provides detailed instructions and procedures for every aspect of preventative maintenance, from removing and preparing the transmission for installation to inspecting, servicing, and troubleshooting the oil system. The manual is organized into nine sections, covering everything from basic maintenance tasks to more complex procedures like dual-mode operation and troubleshooting. Here's a detailed overview of what you'll find in this manual: **Section I: Removing Transmission from Vehicle ** This section provides step-by-step instructions on how to safely remove the Allison HT 750DR transmission from your vehicle. It covers procedures for draining the transmission fluid, disconnecting controls, uncoupling from the driveline and engine, removing mounting bolts, and extracting the transmission itself. The section also includes detailed instructions for removing the input and output flanges or yokes, as well as guidance on rebuild and overhaul procedures. **Section II: Preparing Transmission for Installation ** This section focuses on ensuring the transmission is ready for installation. It covers essential checks, such as inspecting the flywheel (for engine-mounted models), installing the brake and output flange, and securing the input flange (for remote-mounted transmissions). You'll also find instructions for installing the range selector lever, PTO (if applicable), shift modulation control, and the oil filler tube. **Section III: Preparing Vehicle for Transmission Installation** Before installing the transmission, the vehicle needs to be properly prepared. This section guides you through inspections and checks, including verifying the flexplate drive assembly (transmission engine-mounted), checking the input drive components (remote-mounted transmission), examining the chassis and driveline, inspecting the oil cooler, oil filter, and lines, and reviewing the controls. **Section IV: Installing Transmission into Vehicle** This section provides detailed instructions for installing the Allison HT 750DR transmission back into your vehicle, meticulously outlining the process from handling the transmission with care to securing it to the engine (for engine-mounted transmissions). It includes instructions for installing transmission mounting components, rear support for the CLBT 750DB, coupling to the engine (for remote-mounted transmissions), coupling to the driveline, connecting cooler and oil filter lines, and connecting all control components. **Section V: Oil System** Proper oil management is critical for transmission longevity. This section covers filling the system, details on deep oil pans and their interchangeability, spare parts information, installation of the 8 1/2-inch transmission oil pan assembly and oil filler tube, oil level and dipstick procedures, checking transmission oil levels, oil specifications, oil change and filter replacement instructions, and operating temperatures for oil. It also provides guidance on oil levels for the transfer gear housing (dropbox models). **Section VI: Dual Mode Operation** This section provides comprehensive information on the Allison HT 750DR's dual-mode operation, including a general description, functional operation, installation procedures, and specific instructions for downshift inhibiting in CL(B)T 750 models with 2100 and 2300 RPM dropbox models. It also explains the operation of the CLBT 750 dual-mode transmission with dropbox. **Section VII: Release of Step Governor Valve Body Assembly P/N 23010297** This section focuses on the specific step governor valve body assembly, providing general information, interchangeability details, and spare parts information. **Section VIII: Manual/Automatic Operation on Oil Field Equipment** This section provides specific guidance for using the Allison HT 750DR transmission in oil field equipment. It covers general information and detailed instructions for operating with Mannesmann Rexroth Corporation and Bennett shifters. You'll find preventative maintenance procedures for these shifters and information on mode shift valves used in both systems. **Section IX: Troubleshooting CLBT 750 with Dual Mode** This section provides valuable troubleshooting information for the CLBT 750 dual-mode transmission. It includes instructions for locating pressure taps, troubleshooting dual-mode circuitry, and understanding the operation of the step governor valve.

The Allison HT 750DR is a robust and reliable heavy-duty transmission designed for demanding applications in the commercial vehicle industry. It's a part of Allison's renowned series of transmissions known for their durability and efficiency. The HT 750DR is specifically tailored for heavy-duty trucks, buses, and other vehicles operating in harsh environments and under strenuous loads. This transmission boasts a high torque capacity, allowing it to handle heavy loads with ease, while its sophisticated electronic controls ensure optimal performance and fuel efficiency. The HT 750DR is a fully automatic transmission that eliminates the need for manual shifting, reducing driver fatigue and improving overall productivity. It offers seamless gear changes and smooth acceleration, contributing to a comfortable driving experience. The transmission incorporates advanced features such as electronic controls, a robust internal design, and a range of optional features to cater to specific application needs. These features contribute to its longevity and reduce the downtime associated with maintenance and repairs. With its impressive performance, reliability, and user-friendly design, the Allison HT 750DR continues to be a preferred choice for operators in the commercial vehicle sector seeking a transmission that can handle the demands of heavy-duty applications.