Allison began in 1915 in Indianapolis, Indiana, when businessman and motor-racing patron James A. Allison established the Allison Experimental Company, which later became Allison Engine Company. The firm first became famous for aircraft engines, most notably the V-1710 V-12 that powered many American fighters of the Second World War, and it joined General Motors in 1929.

After 1945 Allison redirected its engineering toward automatic transmissions, developing the heavy-duty automatics that made the name a benchmark in buses, trucks, fire apparatus, refuse vehicles and military machines. Well-known product families include the 1000 and 2000 series for medium-duty vehicles, the 3000 and 4000 series for heavy trucks and coaches, and specialist HD and off-highway ranges. Allison transmissions are known for torque-converter durability, electronic shift control and the ability to survive severe stop-start and vocational duty. Allison also developed transmissions for fire apparatus, motorhomes, transit buses and military logistics vehicles, and its products gained a worldwide reputation for low operating cost and long service life in the toughest duty cycles.

Allison workshop manuals are among the most detailed transmission documentation available anywhere. They cover torque converters, gear trains and clutches, hydraulic control systems and valve bodies, electronic control units, sensors and the full wiring diagrams needed for diagnosis. Torque specifications, pressure-test procedures, oil specifications and change intervals, adjustment data, fault codes and step-by-step overhaul instructions are all included.

These manuals benefit fleet maintenance managers, bus and truck garages, independent transmission specialists and owner-operators who want factory-accurate procedures for rebuilding and servicing Allison automatics to original standards. Fleet engineers and owner-operators alike depend on them for the pressure settings, wear limits and rebuild sequences that keep an Allison earning day after day.