Introduction to Modern Vehicle Design

Julian Happian-Smith

• Publisher: Butterworth-Heinemann
• Year: 2001
• ISBN:
  9780080523040
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

An Introduction to Modern Vehicle Design provides a thorough introduction to the many aspects of passenger car design in one volume. Starting with basic principles, the author builds up analysis procedures for all major aspects of vehicle and component design. Subjects of current interest to the motor industry, such as failure prevention, designing with modern materials, ergonomics and control systems are covered in detail, and the author concludes with a discussion on the future trends in automobile design.

With contributions from both academics lecturing in motor vehicle engineering and those working in the industry, "An Introduction to Modern Vehicle Design" provides students with an excellent overview and background in the design of vehicles before they move on to specialised areas. Filling the niche between the more descriptive low level books and books which focus on specific areas of the design process, this unique volume is essential for all students of automotive engineering.

• Only book to cover the broad range of topics for automobile design and analysis procedures
• Each topic written by an expert with many years experience of the automotive industry

1

Automotive engineering development

R.H. Barnard, PhD, CEng, FRAeS

The aim of this chapter is to:

• Introduce the wide range of skills required for vehicle design and manufacture;

• Briefly set the historical scene and development of vehicles and their design;

• Introduce the vast range of possibilities for vehicle design;

• Demonstrate the interactivity of processes within the design and manufacture of vehicles.

1.1 Introduction

In the development of the motor vehicle, there are three readily identifiable groups of activities.

• technical innovation and refinement

• construction, configuration and styling

• methods of production, and manufacturing systems.

To the layman, the most obvious aspects of progress are technical innovations and styling changes, but from a professional engineering viewpoint, the major achievements lie as much in the areas of refinement and systems of manufacture. Innovations can be important in giving manufacturers a competitive advantage, but new ideas often make their debut many decades before they are widely adopted. It is the processes of refinement and production development that make new technical features reliable and cheap enough for use in mass-produced vehicles.

1.2 Innovations and inventions

Engineering history is bedevilled by rival and sometimes false claims to particular inventions. In reality, innovative developments have often been the work of several different engineers working in parallel but quite independently, and the recognized inventor is simply one whose name is well known, or who has been championed for nationalistic reasons. Many apparently new inventions are, in any case, simply adaptations from different technologies. The differential mechanism, for example, was used by watchmakers before being adapted for automotive purposes. It is frequently difficult to trace the earliest examples of the use of a particular device or mechanism. J. Ickx, 1992, describes how the Bollées (father and two sons) invented or adapted an amazing array of devices in the late 19th century, including all-round independent suspension, and power steering (originally applied to steam-powered vehicles). In 1894, the younger Amédée produced a gas turbine, and later went on to invent fuel injection, supercharging, and hydraulic valve lifters. All these devices are usually ascribed to other, later inventors

1.2.1 The first major technical breakthrough

It is a little surprising that road vehicle transport lagged so far behind the development of the railways. Steam locomotives appeared early in the 19th century, and by the time the first really practical road vehicles emerged over half a century later, rail transport had become a mature technology with large networks covering many countries. The problem of road transport development lay in the combination of the heavy cumbersome steam engine and poorly surfaced roads. By the end of the 19th century, significant developments of the steam engine had taken place such as the use of oil or paraffin instead of coal as the fuel, and the development of the lighter more compact ‘flash’ boiler system in which steam was generated by passing water through heated tubes rather than boiling it up in a pressure vessel. Practical steam-powered road vehicles started to appear in small numbers, and indeed for commercial vehicles, the line of development was not finally terminated until the 1950s. Some impression of the level of refinement of steam cars may be drawn from the elegant 1905 Stanley shown in Figure 1.1. Two major drawbacks to automotive steam propulsion were the long start-up time required, and the high rate of water consumption.

Figure 1.1 A Stanley steam car of 1905. This elegant vehicle is far removed from the lumbering smoky traction engines that nowadays chug their way to nostalgic steam rallies. Steam cars were much quieter and smoother-running than their petrol engined contemporaries, but took some time to fire up. They also needed frequent intakes of water.

A major change of direction and a spur to progress, occurred in the 1870s with the appearance of gas-fuelled reciprocating internal combustion engines, notably those patented and produced by Dr A.N. Otto in Germany. Gas engines were originally used as static units for driving machinery, and usually ran on the common domestic or ‘town’ gas, but several engineers started experimenting with the use of vaporized petroleum spirit instead, as this offered the possibility of a mobile engine. Petroleum spirit was at that time a somewhat useless by-product of the process of manufacturing paraffin which was widely used in lamps. In 1885 Gottlieb Daimler modified an Otto four-stroke gas engine to run on petroleum vapour, and fitted it to a crude bicycle with a stabilizing outrigger wheel. One year later, he modified a horse carriage to produce what is now generally recognized as the forerunner of the modern motor car. The invention of the petrol-engined motor car is, however, one of the classic examples of parallel development, and there are many rival claimants, chief amongst these being Karl Benz, who produced a powered tricycle in 1885. A replica of the 1886 version is shown in Figure 1.2. Following the introduction of the petrol engine, road vehicle technology progressed rapidly, but it was the development of mass production techniques rather than any technical innovation that provided the next major step.

Figure 1.2 An 1896 Benz tricycle replica where the influence of bicycle technology is clearly evident. From the collection of the National Motor Museum, Beaulieu.

1.3 Mass production

Most early cars were produced by the same techniques of hand craftsmanship that had been used for centuries for the construction of horse-drawn carriages. Cars required the manufacture of a large number of components, and each item was individually made and fitted by skilled craftsmen. Unlike the modern processes of assembly that simply rely on joining items by bolting or welding, fitting usually involved using hand tools to cut or file components to make them fit together. The great leap in automotive production engineering came when Henry Ford started to develop the techniques of mass production. Ford did not invent the idea; indeed it had been used many years earlier during the American Civil War for the production of rifles. The vehicle that really launched his advanced approach was the Model T (Figure 1.3) which first appeared in 1909. Ford had produced many previous models, working his way through the alphabet from the Model A, and had been gradually honing his production methods. The Model T was one of the first cars whose design was primarily dictated by the requirements of manufacture, and thus it represents an early major example of the application of the concept of 'design for production’.

Figure 1.3 The Ford Model T. This example is from 1913. Note the single transverse front spring and the starting handle, which was the only means of starting. In addition to factory-built vehicles, independent coachbuilders used the Model T chassis as the basis for a wide range of bodywork styles, from trucks and charabanc buses to elegant coachbuilt family cars. The 2898 cc petrol engine gave adequate power for use in quite large commercial vehicles. The spindly chassis was deceptively strong, being made of a vanadium steel alloy. (Photo courtesy of Ford Motor Company Ltd.)

The principle of mass production is that each worker only has to perform either one, or a very limited number of tasks, usually involving very little skill: bolting on the steering wheel for example. To keep the workers continuously busy, the volume of production has to be large.

There must always be another vehicle just ready for its steering wheel. Interestingly, although hand-crafting is always associated in the public’s mind with high quality, mass production actually requires higher standards of accuracy and consistency of dimension, because in mass production, all similar parts must be completely interchangeable. Hand-built cars may look superficially identical, but there are often large differences in the dimensions of individual components. It was the achievement of dimensional accuracy and interchangeability that made mass production possible.

Ford initially assembled the vehicles on fixed stands, but in 1913 he opened his large new Highland Park plant in Detroit (Figure 1.4), and this featured another major innovation, the moving production line. Workers no longer had to move from one task to another; the vehicles simply came to them along a track at an unending steady stream, thereby taking control of the rate of assembly away from the shop-floor workers.

Figure 1.4 Early mass production at Ford’s Highland Park plant in Detroit in 1914: the fuel tank assembly station. The chassis are moved on a track, and the cylindrical fuel tanks are supplied to the assemblers from an overhead store. The production techniques may look somewhat rudimentary by modem standards, but were innovative in their time. (Photo courtesy of Ford Motor Company Ltd.)

Apart from developing the idea of design for production, Henry Ford was also conscious of the need to design for maintainability, and the importance of ergonomic considerations. The Model T was almost the ultimate in simplicity. Initially it had no instruments, and to make driving easier, it had no clutch pedal or gear lever, gear changing being effected by pedals. The owner was supplied with a comprehensive handbook that set out in simple terms how to perform a wide range of maintenance and repair tasks. The construction and layout of the mechanical parts were designed to make most jobs easy, thereby dispensing with the need for a skilled mechanic. The bodywork was minimal and rudimentary. Only one basic chassis was produced, and body colour schemes were initially limited, and finally restricted to one, thereby conforming to the famous slogan ‘any colour you like, as long as it is black’. The black paint was chosen not for aesthetic reasons, but simply because it dried quickly. Ford was also aware of the advantages of using advanced materials, and employed vanadium steel for the chassis, thereby producing a relatively light vehicle.

Like their horse-drawn predecessors, most early cars were expensive, both to purchase and to run, and their ownership was almost entirely restricted to the very wealthy. The major attraction of Ford’s Model T was that its method of production made it much cheaper than competing hand-crafted vehicles. The simplicity of its controls and the fact that it was designed to be readily maintained by an unskilled owner were also good selling points. As a consequence, the Ford T opened up automotive ownership to a new mass market, and by 1923, production had reached a peak of over two million cars per year. Apart from production in the United States, Ford plants were opened in Europe, including one at Trafford Park in England in 1911.

Ford’s enthusiasm for mass production led to his attempting to apply the same principles to a wide range of products, including aeroplanes. He also decided to bring all the stages of car production under his control, not just the final assembly (Ford originally bought in his engines and other components). At Ford’s massive new Rouge plant in Detroit, opened in 1927, raw materials went in one end, and finished cars emerged at the other. Other manufacturers started to copy and even develop these ideas, both in Europe and America, but European cars retained a much higher level of craftsmanship until the outbreak of the Second World War. The requirements of armament production then led to the almost universal acceptance of the principles of mass production.

Mass production made cars available to a large section of the public, but it was soon found to have disadvantages. The hard tedious repetitive work was resented by the assembly workers, who were forced to accept it for want of a comparably paid alternative. The huge plants became organizationally complex and bureaucratic. Worker dissatisfaction made itself apparent in a rash of strikes, as the labour force tried to compensate for the working conditions by seeking ever higher wages and shorter hours. Resentment generated an us-and-them war between shop-floor and management that resulted in some workers taking pleasure in poor workmanship and occasionally, in deliberate sabotage. The resulting products though relatively cheap, were of poor quality, and by the early 1970s, most cars were badly finished, unreliable and prone to rusting. To make matters worse, manufacturers adopted the principle of built-in obsolescence, believing that the faster a vehicle deteriorated, the quicker its owner would need to buy a replacement, thereby increasing sales. There were exceptions to this trend towards poor quality, one of the most notable being the little Volkswagen ‘Beetle’. This vehicle was designed by Ferdinand Porsche in the late 1930s at the behest of Hitler, and although innovative in many respects, it had little in the way of refinement. By the 1970s, its styling was quite antiquated, and its air-cooled engine noisy, yet it sold in extremely large numbers throughout the world. Its success in the USA was particularly surprising, as the American public generally considered European cars to be too small to be either practical or safe. Despite its lack of refinement, the Volkswagen had two great virtues, it was mechanically reliable, and it did not rust quickly. Other manufacturers ...