Allison Transmission

Racing team

Allison began in 1909 when James A. Allison, along with three business partners, helped fund and build the Indianapolis Motor Speedway. In 1911, Allison's new track held the first Indianapolis 500 mile race. In addition to funding several race teams, James Allison founded the Speedway Racing Team Company on September 14, 1915 and quickly gained a reputation for his work on race cars and automotive technology in general. Allison built a shop near the track and changed the team's name to the Allison Experimental Company; the shop later became Plant No. 1.

Wartime aviation

When World War I began, Allison suspended racing, and the Allison Experimental Company began machining parts, tools, and masters for the Liberty airplane engine — the main power plant used in the US war effort. After the war, Allison entered a car in the 1919 Indy 500 and won. It was the last race Allison's team ever entered as he turned his company's attention to aviation engineering, renaming it to Allison Engineering Company; the aviation-focused company developed steel-backed bronze sleeve bearings for the crankshaft and connecting rods, and high-speed reduction gearing to turn propellers and Roots-type blowers. The company's reputation and expertise in aviation was the major factor in General Motors decision to buy the company following James Allison's death in 1928.

Shortly after the sale to General Motors on April 1, 1929, Allison engineers began work on a 12-cylinder engine to replace the aging Liberty engines. The result was the V1710 12-cylinder aircraft engine and it made the company, renamed to the Allison Division of GM in 1934, also known as the Allison Engine Company, a major force in aviation. Plant 3 was built in 1939, a 360,000 sq ft factory to build V1710 engines. Due to demand during World War II, Allison would add a second factory and 23,000 new employees; by the end of the war, Allison had built 70,000 V1710 engines.

Early transmission development

Alongside the development and production of the V1710, engineers at GM began designing the CD-850 cross-drive steering transmission for tracked military vehicles in 1941; the design was completed in 1944 and Allison was awarded the contract to manufacture the prototypes. In February 1945, General Motors formed the Allison Transmission Engineering Section, dividing the subsidiary into Aircraft Operations and Transmission Operations in 1946. The CD-850 combined range change, steering and braking. Allison stopped producing the CD-850 in 1986, but a licensed version was produced in Spain for more than a decade afterward.General Motors began developing automatic transmissions with a hydraulic torque converter in the 1930s under its Product Study Group, offering it as an option for Oldsmobile for the first time in 1940. After World War II, Allison Transmission turned its attention to civilian transportation. Allison designed, developed and manufactured the first-ever automatic transmissions for heavy-duty vehicles including delivery trucks, city buses, and locomotives, starting from 1948. In addition, Allison marketed transmissions for off-highway heavy-duty vehicles under the brand Powershift TORQMATIC, with the first TG series transmissions being produced in July 1948.

V-Drive

At approximately the same time the CD-850 was going into production, GMC Truck and Coach Division requested that GM develop a V-Drive transmission with a torque converter in 1945 for transit bus use, replacing the Spicer manual transmission then offered. These buses had rear-mounted engines and to maximize passenger space, the engine compartment was minimized; the V-Drive transmission was named for the 63° angle of intersection between the transmission shaft input and output . Development of the V-Drive transmission was led by Bob Schaefer, an emigrant from Germany who had joined GM in 1942 after helping to lead the Twin Disc Company, which was one of the licensees of the Ljungstroms hydraulic torque converter. Schaefer was reassigned from the Detroit Transmission Division to Allison in 1946.

The first production V-Drive transmissions were delivered in October 1947, with the first major contract being for 900 buses in 1948, for New York City. The VS-2 was introduced in 1955, which added a two-speed input splitter; a version with both hydraulic and direct clutches was introduced in 1958 , and production of the original V-Drive transmissions was concluded in July 1976, with 65,389 produced.

Commercial transmissions

In addition to the transit bus market, Allison began developing automatic transmissions for commercial trucks in 1953. This effort resulted in the MT-25, which designated the intended application and maximum input power, 250 hp . The MT-25 was a 6-speed automatic, using a two-speed high/low splitter and three-speed double planetary gear train. The splitter was equipped with a hydraulic retarder. Because of the additional cost of the automatic transmission, sales were initially slow until Allison began targeting specific markets that required both on- and off-road driving as well as frequent stops and starts, such as concrete mixing and garbage trucks in the early 1960s. The MT-25 was fitted first as an option branded POWERMATIC by Chevrolet, exclusive to that brand for the first year, but was soon offered by other truck manufacturers including Ford , Reo , Dodge , Diamond T , White , and International Harvester ; production of the MT-25 continued into the early 1970s.The MT-25 was supplemented in September 1970 by a second-generation lighter-duty automatic transmission, the four-speed AT-540, which Allison developed jointly with Hydramatic Division in the late 1960s; the AT-540 was targeted specifically for on-highway use and shared similarities with automobile transmissions to reduce the cost penalty to equip on-highway trucks with automatic transmissions. Later, the MT-25 itself was replaced by the MT-640 and a heavier-duty version, the HT-740, was introduced; the new MT and HT were both derived from the AT-540. As an option, the MT-6nn and HT-7nn series transmissions could be equipped with a lower fifth gear for severe off-road conditions. In 1970, GM combined the Allison and Detroit Diesel divisions as the Detroit Diesel Allison Division of GM.The 500-series transmissions were rated to accept input power of up to 235 hp and were intended for vehicles up to 30,000 lb gross vehicle weight . The medium-duty 600-series had increased ratings to 300 hp and 73,280 lb GVW, while the heavy-duty 700-series were rated to 445 hp and 80,000 lb GVW. In 1976, a 700-series V-Drive transmission was introduced for buses, the V730. The AT/MT/HT were still being produced in 1998.Allison also produced off-highway transmissions in the 1960s, starting with the "Dual Path Powershift" DP 8000 series. The first electronic controls were fitted to the off-highway DP 8000 series transmission in 1971. Electronic controls were added to the MT/HT/V730 in 1983, improving fuel economy by more precisely controlling shifts.

World Transmission

The third-generation six-speed World Transmission was introduced in 1991, replacing the second-generation AT/MT/HT/V730 lines. Development of the WT had begun in the mid-1980s, prior to the sale of Detroit Diesel to Roger Penske in 1987. The WT used the WT electronic control system to control the internal clutches during shifting, equipped with a control unit that adapts to variations during use. The WT line was split into MD , HD , and B lines; the MD and HD lines were later renamed to the 3000 and 4000 Series, respectively.

As of 1998 in the United States, Allison had built 92% of the transmissions in school buses; 75% of transit bus transmissions, 65% of heavy-duty garbage truck transmissions, and 32% of all medium-duty truck transmissions.Allison followed the WT line with the 1000 and 2000 Series starting in 1999. The 1000 Series transmission incorporated many features from the WT line for light-duty trucks, including the electronic control system, and was initially available as an option with the 6.6L GM/Isuzu Duramax diesel engine and the 8.1L Vortec gasoline engine for the trucks based on the GMT800 platform.In 2007, GM sold Allison Transmission to private equity firms Carlyle Group and Onex Corporation for US$5.6 billion.