Page 222 - Automotive Engineering Powertrain Chassis System and Vehicle Body

CH AP TER 8 .1 Types of suspension and drive

Fig. 8.1-35 On a front-wheel drive (left) the vehicle is pulled.
The result is a more stable relationship between the driving
forces F X,W,a and the inertia force F c,V Conversely, in the case of
driven rear wheels an unstable condition is theoretically evident;
front axle settings ensure the necessary stabilization.

the considerable need for stability of the bodywork in
the region of those points on the front bearings at
which complex, superposed forces have to be
Fig. 8.1-37 The front rigid axle on the Mercedes-Benz light
transmitted. commercial vehicle of the 207 D/308 series with recirculating
ball steering gear and steering rod 1 parallel to the two-layer
parabolic spring. This rod has to be slightly shorter than the
8.1.4 Front-mounted engine, front side of the spring, so that both parts take on the same
motion curve when the axle bottoms out (see also Fig. 9.1-6).
rear-mounted drive The brace 3, running from the steering column jacket 2 to the
body, bends on impact.
The T-shaped axle casing 4, which is cranked downwards and
In passenger cars and estate cars, the engine is approxi-
to which the springs are fastened, can be seen in the section.
mately in the centre of the front axle and the rear wheels The elastomer spring 5 sits on the longitudinal member of the
are driven (Fig. 8.1-32). To put more weight on the rear frame and the two front wheels are joined by the tie rod 6. The
axle and obtain a more balanced weight distribution, Alfa safety steering wheel has additional padding.
Romeo, Porsche (928, 968 models) and Volvo integrated
the manual transmission with the differential. This is also gives hardly any other option. Articulated lorries, where
the case with the Chevrolet Corvette sports car (1998; a major part of the trailer weight – the trailer hitch load – is
Figs. 8.1-33 and 8.1-34). With the exception of light carried over the rear wheels, have the same configuration.
commercial vehicles, all lorries have the engine at the On buses, however, the passengers are spread evenly
front or centrally between the front and rear axles to- throughout the whole interior of the vehicle, which is why
gether with rear-wheel-drive vehicles. The long load area there are models with front, central and rear engines.

Front-wheel drive Rear-wheel drive Rear engine
front rear front rear front rear
Empty 61 39 50 50 40 60
2 passengers at the front 60 40 50 50 42 58
4 passengers 55 45 47 53 40 60
5 passengers and luggage 49 51 44 56 41 59

Fig. 8.1-36 Average proportional axle load distribution based on drive type and loading condition. With the standard-design saloon,
when the vehicle is fully laden, the driven rear wheels have to carry the largest load. With the front-wheel drive, however, with only
two persons in the vehicle, the front wheels bear the greater load.

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