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A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the long axis of the vehicle. Many modern front wheel drive vehicles use this engine mounting configuration. (The vast majority of rear wheel drive vehicles use a longitudinal engine configuration, where the engine's crankshaft axis is parallel to the long axis of the vehicle.)
The first car known to use such an arrangement was a 1911 front-wheel drive car with a clutch at each end of the engine, driving the front wheels directly. The first successful transverse-engine cars were the two-cylinder DKW "Front" series of cars, which first appeared in 1931. After the Second World War, SAAB used the configuration in their first model, the Saab 92, in 1947. The arrangement was also used for Borgward's Goliath and Hansa brand cars and in a few other German cars. However, it was with Alec Issigonis's Morris Mini and Austin Seven that the design gained acclaim, in 1959.
This design reached its ultimate extent starting with Dante Giacosa's elaboration of it for Fiat. He connected the engine to its gearbox by a shaft and set the differential off-center so that it could be connected to the gearbox more easily. The axleshafts from the differential to the wheels therefore differed in length, which would have made the car's steering asymmetrical were it not for their torsional stiffness being made the same. Now most small and small/medium sized cars built throughout the world use this arrangement.
The Land Rover LR2 Freelander, along with all Volvo models from 1998 on (including V8 models), employ a transversely-mounted engine in order to increase passenger space inside the vehicle. This has also allowed for improved safety in a frontal impact, due to more front to back engine compartment space being created. The result is a larger front crumple zone.
Transverse engines have also been widely used in buses. In the United States they were offered in the early 1930s by Twin Coach and used with limited success in Dwight Austin's Pickwick Nite-Coach. Transverse bus engines first appeared widely in the Yellow Coach 719, using Dwight Austin's V-drive; they continued in common use until the 1990s, though shorter V-configuration engines in a straight in "T-drive" configuration became common in the 1960s. They were also used in the British Leyland Atlantean and in many transit buses and nearly all modern double decker buses. They have also been widely used by Scania, MAN, Volvo and Renault's bus divisions.
Position placement of transverse engines
Engines may be placed in two main positions within the motor car:
- Front-engine transversely-mounted / Front-wheel drive
- Rear mid-engine transversely-mounted / Rear-wheel drive
Common types of transversely placed engines
Space allowed for engines within the front wheel wells is commonly limited to the following:
Alternative convention with V-twin motorcycles
The description of the orientation of a V-twin engine in a motorcycle often contradicts the given convention. V-twin engines in Moto Guzzi motorcycles are called "transverse" although the crankshaft is mounted in line with the frame, while V-twins in Ducati motorcycles, which have their crankshafts mounted perpendicular to the frame and would be considered transverse by the given convention, are called "longitudinal". This convention uses the longest horizontal dimension (length or width) of the engine as its axis instead of the line of the crankshaft.
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Moto Guzzi's tranverse V-twins are unique among motorcycles, while Ducati, in keeping with the classical school, uses a longitudinal V, meaning the axis of rotation of the crankshaft is transverse to the frame.
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