Transaxle

In the automotive field, a transaxle is a major mechanical component that combines the functionality of the transmission, the differential, and associated components of the driven axle into one integrated assembly.

Transaxles are near universal in all automobile configurations that have the engine placed at the same end of the car as the driven wheels: the front-engine, front-wheel drive layout, rear-engine, rear-wheel drive layout and rear mid-engine, rear-wheel drive layout arrangements.

Many mid- and rear-engined vehicles use a transverse engine and transaxle, similar to a front wheel drive unit. Others use a longitudinal engine and transaxle like Ferrari's 1989 Mondial t which used a "t" arrangement with a longitudinal engine connected to a transverse transaxle, a design the company continues to this day. Front-wheel drive versions of modern Audis, from the A4 upwards, along with their related marques from the Volkswagen Group (which share the same automobile layout) also use a similar layout, but with the transaxle also mounted longitudinally.

Front-engine, rear-wheel drive transaxles

Csonka transaxle from 1908.

Front-engine, rear-wheel drive vehicles tend to have the transmission up front just after the engine, but sometimes a front engine drives a rear-mounted transaxle. This is generally done for reasons of weight distribution, and is therefore common on sports cars. Another advantage is that as the driveshaft only spins at engine speed it only has to endure the torque of the engine, instead of that torque multiplied by the 1st gear ratio. This design was pioneered in the 1934 Škoda Popular, and then in the 1950 Lancia Aurelia, designed by the legendary Vittorio Jano.

Since this placement of the gearbox is unsuitable for a live axle (due to excessive unsprung weight), the rear suspension is either independent, or uses a de Dion tube (notably in the Alfa Romeos). Rare exceptions to this rule were the Bugatti T46 and T50 which had a three speed gearbox on a live axle.

The Nissan GT-R is unique in that it uses a rear transaxle with a AWD layout, the transaxle in this case also contains the differential sending power back to the front wheels via a separate driveshaft.

Notable Front-engine, rear-wheel drive layout vehicles with a transaxle design include:

• 1898-1910 De Dion Bouton
• 1914–1939 Stutz Bearcat
• 1929–1936 Bugatti Type 46
• 1934–1944 Škoda Popular and Škoda Rapid
• 1946–1952 Škoda Tudor and Škoda 1101
• 1950–1958 Lancia Aurelia
• 1951–1956 Pegaso Z-102
• 1957–1970 Lancia Flaminia
• 1961–1963 Pontiac Tempest
• 1964–1968 Ferrari 275
• 1963-1968 Ferrari 330
• 1968–1973 Ferrari Daytona
• 1972–1987 Alfa Romeo Alfetta
• 1974–1987 Alfa Romeo GTV/Alfa Romeo GTV6
• 1976–1988 Porsche 924
• 1976–1991 Volvo 300 series
• 1977–1985 Alfa Romeo Giulietta
• 1978–1995 Porsche 928
• 1982–1995 Porsche 944 and Porsche 968
• 1984–1987 Alfa Romeo 90
• 1985–1992 Alfa Romeo 75
• 1989–1991 Alfa Romeo SZ
• 1992–2003 Ferrari 456
• 1996–2005 Ferrari 550/575M
• 1997–up Chevrolet Corvette
• 1997–1999 Panoz Esperante GTR-1
• 1997-2002 Plymouth Prowler
• 1998-2005 Shelby Series 1
• 2003-2006 Chevrolet SSR
• 2003–on Aston Martin DB9
• 2004–on Ferrari 612 Scaglietti
• 2004–on Maserati Quattroporte
• 2005–up Aston Martin V8 Vantage
• 2006–up Ferrari 599 GTB Fiorano
• 2008-up Alfa Romeo 8C Competizione
• 2009–up Lexus LF-A
• 2010-up Mercedes-Benz SLS AMG

Rear-engine, rear-wheel drive transaxles

Volkswagen and later Porsche made extensive use of transaxles in their rear (and mid) engined vehicles, including:

• 1934-1936 Mercedes-Benz 150H
• 1960-1969 Chevrolet Corvair
• 1948–1965 Porsche 356
• 1963–present Porsche 911
• 1965–1969, 1976 Porsche 912
• 1969–1976 Porsche 914 (mid-engined)
• 1975–1989 Porsche 930
• 1938–2003 Volkswagen Beetle
• 1955–1974 Volkswagen Karmann Ghia
• 1950–present Volkswagen Type 2
• 1961–1973 Volkswagen Type 3
• 1968–1974 Volkswagen Type 4

Rear-engine, rear-wheel drive layout is also the preferred layout for Dune Buggy, Sandrail, and most other non-truck based race cars used in off-road racing.

Four-wheel drive

All Audi cars with longitudinal engines and their 'trademark' quattro four-wheel drive (4WD) system, along with their related marques from the Volkswagen Group which share the same layout, utilise a transaxle. This is mounted immediately behind the front-mounted engine (again, longitudinally) and contains the 'gearbox' (manual, automatic, DSG, or CVT), along with both the centre differential, and the front differential and final drive unit.

Other 4WD applications include:

• 1984–1986 Ford RS200 – mid-engined, with the gearbox in the front;
• 2007–on Nissan GT-R – front-engined, with the gearbox in the rear.

See also

• Hybrid Synergy Drive
• Unit frame layout - early tractor configuration

External links

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