Monday, December 26, 2011

Citroen Traction Avant

The Traction Avant, French for "front wheel drive", was designed by André Lefèbvre and Flaminio Bertoni in late 1933 / early 1934. While not the first production front wheel drive car – Alvis built the 1928 FWD in the UK, Cord produced the L29 from 1929 to 1932 in the United States and DKW the F1 in 1931 in Germany – it was the world's first front-wheel drive steel monocoque production car. Along with DKWs 1930s models, the Traction successfully pioneered front-wheel drive on the European mass car market.
Traction Avant monocoque
The Traction Avant's structure was a welded monocoque (unitized body). Most other cars of the era were based on a separate frame (chassis) onto which the non-structural body ("coachwork") was built. Monocoque construction (also called Unit Body or "Unibody" in the US today) results in a lighter vehicle, and is now used for virtually all car construction, although body-on-frame construction remains suitable for larger vehicles such as trucks.
This method of construction was viewed with great suspicion in many quarters, with doubts about its strength. A type of crash test was conceived, taking the form of driving the car off a cliff, to illustrate its great inherent resilience.[2]
The novel design made the car very low-slung relative to its contemporaries – the Traction Avant always possessed a unique look, which went from appearing rakish in 1934 to familiar and somewhat old fashioned by 1955.

Front torsion bar suspension
The suspension was very advanced for the car's era. The front wheels were independently sprung, using a torsion bar and wishbone suspension arrangement,[3] where most contemporaries used live axle and cart-type leaf spring designs. The rear suspension was a simple steel beam axle and a Panhard rod, trailing arms and torsion bars attached to a 3-inch (76 mm) steel tube, which in turn was bolted to the monocoque.
Since it was considerably lighter than conventional designs of the era, it was capable of 100 km/h (62 mph), and consumed gasoline/petrol only at the rate of 10 litres per 100 kilometres (28 mpg-imp; 24 mpg-US).

The original model, which was presented on 18 April 1934, was a small saloon with a 1,303 cc (79.5 cu in) engine. This model was called the 7A, which was succeeded in June 1934 by the 7B with a higher-power engine of 1,529 cc (93.3 cu in). The 7B in turn, was succeeded in October 1934 by the 7C with an even higher-output 1,628 cc (99.3 cu in) engine. Later models were the 11 (launched in November 1934), which had a 1,911 cc (116.6 cu in) four-cylinder engine, and the 15 (launched in 1938), with a 2,867 cc (175.0 cu in) six. The numbers refer to the French fiscal horsepower rating, or CV. The 11 was an 11 CV, but curiously the 15 was actually 16 CV. The 11 was built in two versions, the 11L ("légère", or "light"), which was the same size as the 7 CV, and the normal model 11, which had a longer wheelbase and wider track.
A French "familiale" 11 F 1954, 6 windows, 9 seats
Citroën planned two variants that never entered production, since there was not enough funding available to develop them, except as running prototype vehicles. One was an automatic transmission-equipped model, based on the Sensaud de Lavaud automatic transmission, the other a 22 CV model with a 3.8 liter V8. The transmission (which was actually originally designed for the Citroen) was a "gearless" automatic, using the torque-converter alone to match engine revolutions to the drivetrain revolutions, much like the Dynaflow Transmission introduced later in the USA. The car was supposed to have a less spartan interior than the other Traction Avants and it was to feature Citroën's own new V8 engine. About twenty prototypes were made, but when the project was canceled in 1935 due to Michelin's takeover; they were probably all destroyed.[citation needed]
In addition to the 4-door body, the car was also produced as a 2-door coupé with a rumble seat, as a convertible and as an extended length Familial model with three rows of seats. There was even a hatchback-type Commerciale variant, in 1939, well ahead of its time, in which the tailgate was in two halves, the lower of which carried the spare wheel with the upper opening up to roof level. A one-piece top-hinged tailgate was introduced when the Commerciale resumed production in 1954 after being suspended during World War II.

 Source : wikipedia

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