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Atransverse engine is anengine mounted in a vehicle so that the engine'scrankshaft axis isperpendicular to the direction of travel. Many modernfront-wheel drive vehicles use this arrangement. Mostrear-wheel drive vehicles use alongitudinal engine, where the engine's crankshaft axis is parallel with the direction of travel. (Somerear-mid engine vehicles use a transverse engine andtransaxle mounted in the rear instead of the front). Transverse engines save space in light vehicles, and are used onarmoured fighting vehicles for the same reason.
TheCritchley light car, made by theDaimler Motor Company in 1899, had a transverse engine withbelt drive to the rear axle.[1][2] The first successful transverse-engine cars were the two-cylinderDKW F1 series of cars, which first appeared in 1931.
During WWII, transverse engines were developed for armored vehicles, with the SovietT-44 andT-54/T-55tanks being equipped with transverse engines to save space within the hull. The T-54/55 eventually became the most produced tank in history.
After theSecond World War,Saab used the configuration in their first model, theSaab 92, in 1947.[3] The arrangement was also used forBorgward'sGoliath andHansa brand cars.TheEast German-builtTrabant, which appeared in 1957, also had a transversely mounted two stroke engine, and this design was kept until the end of production, in 1991. However, it was withAlec Issigonis'sMini, introduced by theBritish Motor Corporation in 1959, that the design gained acclaim. Issigonis incorporated the car'stransmission into the engine'ssump[disambiguation needed], producing a drivetrain unit narrow enough to install transversely in a car only 4 feet (1.2 m) wide. While previous DKW and Saab cars used small, unrefinedair-cooledtwo-stroke engines with poor performance, the gearbox-in-sump arrangement meant that an 848 cc four-cylinder water-cooled engine could be fitted to the Mini, providing strong performance for a car of its size. Coupled to the much greater amount of interior space afforded by the layout (the entire drivetrain only took up 20% of the car's length), this made the Mini a genuine alternative to the conventional small family car.
This design reached its peak starting withDante Giacosa's elaboration of it forFiat. He connected the engine to its gearbox by a shaft and set thedifferential off-center so that it could be connected to the gearbox more easily. Thehalf shafts 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. Giacosa's layout was first used in theAutobianchi Primula in 1964 and later in the popularFiat 128. With the gearbox mounted separately to the engine, these cars were by necessity larger than the Mini, but this proved to be no disadvantage. This layout, still in use today, also provided superior refinement, easier repair and was better-suited to adopting five-speed transmissions than the original Issigonis in-sump design.
TheLamborghini Miura used a transverse mid-mounted4.0-litre V12. This configuration was unheard of in 1965, but became more common in the following decades, with cars such as theLancia Montecarlo,Noble M12,Toyota MR2,Pontiac Fiero, andfirst-generation Honda NSX using such a powertrain design.
TheLand 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 longitudinal engine compartment space being created. The result is a larger frontcrumple zone.[4][5]
Transverse engines have been widely used in buses. In the United States, they were offered in the early 1930s byTwin Coach and used with limited success in Dwight Austin's Pickwick Nite-Coach. Transverse bus engines first appeared widely in theYellow Coach 719, using Dwight Austin's V-drive; they continued in common use until the 1990s, though shorter V-configuration engines in a longitudinal "T-drive" configuration became common in the 1960s. Transverse engines were used in the BritishLeyland Atlantean, in many transit buses, and in nearly all moderndouble decker buses. They have been widely used byScania,[6]MAN,Volvo andRenault's bus divisions.
Engines may be placed in two main positions within the motor car:
Space allowed for engines within the front wheel wells is commonly limited to the following:
The description of the orientation of V-twin and flat-twin motorcycle engines sometimes differs from the convention as stated above. Motorcycles with aV-twin engine mounted with its crankshaft parallel to the direction of travel, e.g. theAJS S3 V-twin,Indian 841,Victoria Bergmeister,Honda CX series and severalMoto Guzzis since the 1960s, are said to have "transverse" engines,[7][8]
Moto Guzzi's transverse 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.