Ever since the first motor vehicle was produced, inventors, engineers, designers and scientists have striven to improve them using the latest technology and materials. As time has passed, we have seen and experienced many changes in design and development to give us today’s motor vehicles. Learning from those early designs, and with today’s manufacturing skills, vehicle manufacturers can now produce motor vehicles that use very strong but lightweight materials in their structure and drive train. Many innovative materials are also now used in vehicle manufacture, some of which are recyclable, which helps reduce costs and reduces the environmental impact of the industry.
As we now live in a world of electronic technology, the motor vehicle has become a designer’s dream in providing systems that continue to improve the protection of its occupants, provide stability and economy and also take interior comfort to new levels of refinement. Packaged with this, we now have engines and transmissions that are high performance, environmentally friendly and economical to run, giving today’s drivers an exciting all-round driving experience with a very high level of safety. Whatever the level of comfort or performance whether it be tires to Formula 1 high performance traction tires we are in the midst of a motor car renaissance. The following sections outline the fundamentals in vehicle construction and design on which the reader can build their understanding of the latest developments.
At a very early stage in human history people must have realised that the human body was severely limited in terms of the loads it could carry and the distance it could carry them. Furthermore, it is safe to assume that the physical exertion involved was no more to people’s liking then than it is today.
Much progress was achieved through the domestication of suitable animals to enable heavier loads to be carried greater distances, often at greater speeds than people were capable of attaining. There was the added advantage that, as most of the effort was provided by the animal, the people could travel at their ease and in relative comfort.
At first, heavy loads were dragged upon sledges until an early and unknown engineer Invented the wheel. This made it possible to construct crude carts upon which even heavier loads could be carried more easily. The one drawback to the use of wheeled vehicles was – and still is – the necessity of providing a reasonably smooth and hard surface upon which the wheels could run. The development of wheeled vehicles, therefore, Is closely related to the development of roads.
As new materials and manufacturing methods were developed, it became possible to make improvements in vehicles, but as long as animals were the only form of motive power it was not possible to significantly increase loads and speeds. The development of the steam engine during the 18th and 19th centuries led to Its application to the driving of vehicles, and though some of the early attempts were crude and not very successful, several extremely promising carriages were produced. These might have been developed into very practical vehicles had not restrictive legislation forced them off the roads. In any case, the steam engine proved less suited to road vehicles than it did to the railway. It was the successful development of the light, high-speed internal-combustion engine towards the end of the 19th century that really opened up the way to the power-driven road vehicle, and that made possible the development of the modern motor car, truck, bus and coach.
Development of layout
Motor vehicles were developed from horse-drawn carriages – they were, In fact, originally called ‘horseless carriages’ – and naturally owed something of their general form to those carriages. For instance, the system of four wheels arranged one at each end of two transverse axles so that their points of contact with the ground are at the corners of a rectangle (see Figure 1.la) has been used on carts and wagons since time immemorial and is still by far the commonest arrangement. While three wheels are sufficient to give stability, they do not provide so much ‘useful space’ for a given amount of road space taken up (compare Figure l.la with Figure Lib).
The horse was invariably put in front of the cart, to put) it rather than push it, to allow the animal to see where it was going and the driver to keep an eye on the horse. The driver steered the vehicle through shafts attached to a front axle, which could pivot about its centre, and when it came to replacing the horse by an engine, it was natural that front-wheel steering should be retained, at least for a while. It was not long, however, before vehicles with rear-wheel steering were tried, but it was soon found that rear-wheel steering had disadvantages that ruled it out for general use. For example, a vehicle steered by its rear wheels would steer to the right by deflecting its rear end to the left, making it impossible to drive away forwards from a position close to a wall or kerb (see Figure 1.2). A rear-wheel-steered car moving at any speed and coming alongside a wall, kerb, ditch or another vehicle could very easily find itself in a situation in which a collision could not be avoided.
The swivelling axle arrangement is not very satisfactory for powered vehicles, partly because a good deal of space must be left for the axle and wheels to swivel. Also, if one wheel strikes an obstruction, such as a large stone, it is extremely difficult, without the leverage of the long shafts, to prevent the axle swivelling about its pivot, causing the vehicle to swerve off the road. An alternative arrangement, whereby the wheels were carried on stub axles free to pivot at the ends of a fixed axle, had already been used on some horse carriages, and this was soon adopted for motor vehicles.
When it came to using mechanical power to drive vehicles, it was natural that the power should be applied to the non-steerable wheels, since the problem of driving these is simpler than powering the driving wheels which have also to be swivelled for steering purposes. This explains why in the past, rear-wheel drive was universally adopted. The increased load on the rear wheels when climbing hills or accelerating gives a better grip, making rear-wheel drive attractive. Front-wheel drive vehicles lose this advantage, so under these conditions the wheels spin more easily.