Front-Wheel Drive (FWD) layouts.
Front-Wheel Drive (FWD):
Front-wheel drive (FWD) is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel-drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in rear-wheel-drive and four-wheel-drive vehicles.
FF means “Front engine, Front-Wheel Drive”.
This type of layout has suffered important changes through time;
Early cars using the FF layout include the 1929 Cord L-29, 1931 DKW F1, the 1948 Citroën 2CV, 1949 Saab 92 and the 1959 Mini. In the 1980s, the traction and packaging advantages of this layout caused many compact and mid-sized vehicles to adopt it.
There are four different arrangements for this basic layout, depending on the location of the engine, which is the heaviest component of the drivetrain.
Mid-engine / Front-wheel drive
The earliest such arrangement was not technically FF, but rather mid-engine, front-wheel-drive layout (MF). The engine was mounted longitudinally (fore-and-aft, or north-south) behind the wheels, with the transmission ahead of the engine and differential at the very front of the car. With the engine so far back, the weight distribution of such cars as the Cord L-29 was not ideal; the driven wheels did not carry a large enough proportion of weight for good traction and handling. The 1934 Citroën Traction Avant solved the weight distribution issue by placing the transmission at the front of the car with the differential between it and the engine. Combined with the car’s low slung unibody design, this resulted in handling which was remarkable for the era. Citroën and Renault used this layout in some models into the 1980s.
The Renault 5 was one of the last successful mid-engine, front-wheel-drive layouts.
Front-engine longitudinally mounted / Front-wheel drive
The 1946 Panhard Dyna X, designed by Jean-Albert Grégoire, had the engine longitudinally in front of the front wheels, with the transmission behind the engine and the differential at the rear of the assembly. This arrangement, used by Panhard until 1967, potentially had a weight distribution problem analogous to that of the Cord L29 mentioned above. However, the Panhard’s engine was very light, reducing the effect. The engine of the Citroën 2CV was in front of the front wheels, with the transmission behind the axle and the differential between the two. This became quite popular; cars using this layout included the German Ford Taunus 12M and the Lancia Flavia and Fulvia. This is the standard configuration of Audi and Subaru front wheel drive vehicles. The first generation Oldsmobile Toronado and the Saab 99 and “classic” Saab 900 had their engines mounted approximately on the front axle center line, with power being taken by chains or a gear train to a transmission and differential mounted below and beside the engine.
Front-engine transversely mounted / Front-wheel drive
Issigonis‘s Mini of 1959 and related cars such as the Maxi, Austin 1100/1300 and Allegro had the engine transversely mounted. The transmission was located in the sump below the crankshaft, with power transmitted by transfer gears. The 1955 Suzuki Suzulight also introduced a front engine with a transversely installed engine in a city car/kei car application.
Dante Giacosa‘s Autobianchi Primula of 1964, Fiat 128 and Fiat 127, put the transmission on one side of the transversely mounted engine, and doubled back the drivetrain to put the differential just behind the transmission, but offset to one side. Hence the driveshafts to the wheels are longer on one side than the other. This located the weight just a bit in front of the wheels. It is this system which dominates worldwide at present.
Vehicles with the Giacosa arrangement tend to suffer from torque steer under heavy acceleration. The shorter drive shaft, being stiffer than the longer drive shaft, transmits the motion to the wheels immediately instead of ‘winding’ up due to the drive torque. The net result is more tractive force at the wheel with the shorter drive shaft and the car tends to pull to the opposite side.
Rear-engine, Front-Wheel Drive:
A rear-engine, front-wheel-drive layout is one in which the engine is behind the rear wheels, but drives the front wheels via a driveshaft, like a conventional front-engine, rear-wheel-drive vehicle traveling in reverse.
There is some interest in developing the idea for use in cars of the future, as evidenced by the patent application of inventor–engineer Michael Basnett at Rover Group (GB), who proposes a front transaxle design, rear flat engine architecture.
Posted on July 21, 2012, in General, Uncategorized and tagged cars, ff, ff layout, front mid engine, front wheel drive, fwd, fwd layout, honda civic type R, internal combustion engine, live for speed, sport FF car, sport front wheel car, transportation, wheel drive vehicles, xfg. Bookmark the permalink. 1 Comment.