Entire Vehicle [2 ed.] 9783662670699, 9783662670705

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Commercial Vehicle Technology

Michael Hilgers

Entire Vehicle Second Edition

Commercial Vehicle Technology Series Editor Michael Hilgers, Weinstadt, Baden-Württemberg, Germany

Michael Hilgers

Entire Vehicle Second Edition

Michael Hilgers Daimler Truck Stuttgart, Germany

ISSN 2747-4046 ISSN 2747-4054  (electronic) Commercial Vehicle Technology ISBN 978-3-662-67069-9 ISBN 978-3-662-67070-5  (eBook) https://doi.org/10.1007/978-3-662-67070-5 © Springer-Verlag GmbH Germany, part of Springer Nature 2021, 2023 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer Vieweg imprint is published by the registered company Springer-Verlag GmbH, DE, part of Springer Nature. The registered company address is: Heidelberger Platz 3, 14197 Berlin, Germany

Preface

For my children Paul, David and Julia, who share my passion for trucks, and for my wife Simone Hilgers-Bach who indulges us.

I have worked in the commercial vehicle industry for many years. I constantly hear comments which express essentially the same sentiment, “You develop trucks? That’s a young boy’s dream!” Indeed it is! Inspired by this enthusiasm, I have tried to learn as much as I possibly can about what goes into making commercial vehicles. In the process, I have discovered that one has not really grasped the subject matter until one can explain it cogently. Or to put it more clearly, “In order to really learn, you must teach.” Accordingly, as time went on I began to write down as many technical aspects of commercial vehicle technology as I could in my own words. I very quickly realized that the entire project needed to be organized logically, and once that was in place, the basic framework of this series of booklets on commercial vehicle technology practically compiled itself. This booklet in the series Commercial vehicle technology provides an introduction to the entire vehicle. The commercial vehicle is explained from the point of view of the user, that is to say the customer who uses the vehicle to earn a living. This is followed by a discussion of the fundamental qualities of the commercial vehicle as a whole. Most of the considerations apply both to the conventional diesel fuelled commercial vehicles and to future vehicle concepts with alternative drivetrains. Other books in this series then deal with specific technical systems like the propulsion system or the cab. Sometimes regulations and limits are mentioned and explained in this series of booklets for illustration. Especially this booklet on entire vehicle often refers to regulations. Please be aware at all times that all regulations might change, and that this booklet may not be up to date. It is good practices to regularly check with experts to obtain the latest version of regulations.

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Preface

Finally, I have a personal favor to ask. It is important to me that this work should continue to be expanded and refined. In this, valued readers, I would sincerely welcome your help. I ask that you send technical notes and suggestions for improvement to the following email address: [email protected]. The more specific your comments are, the easier it will be for me to understand their implications, and possibly incorporate them in future editions. And now I wish you much enjoyment reading this booklet the Entire vehicle. Weinstadt-Beutelsbach Beijing Aachen December 2022

Michael Hilgers

Contents

1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 A Few Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 The Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 2 4 5

2 Trucks as Investment Goods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 The Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Profitability of the Commercial Vehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Optimizing Income. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.2 Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Profitability and Cost Structure for Alternative Propulsion Systems. . . . . . 2.4 Profitability and Cost Structure for Autonomous Driving Trucks. . . . . . . . 2.5 Trucks from the Driver’s Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 Customer Purchasing Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7 7 9 9 10 15 15 16 16

3 Entire Vehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 The Vehicle Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Tractor Unit or Truck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 Vehicle Configuration and Operating Case . . . . . . . . . . . . . . . . . . . 3.1.3 Effects of Production on the Vehicle Concept. . . . . . . . . . . . . . . . . 3.2 Vehicle Variants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Axle Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Geometry of the Vehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Dimensions in Europe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Weight and Size Regulations in the US. . . . . . . . . . . . . . . . . . . . . . 3.3.3 Conventional and cab-over-engine tractors in Light of the Length Regulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Weights and Axle Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 Permissible Gross Vehicle Weights and Gross Combination Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19 19 21 23 24 25 25 25 26 26 28 30 32 32 vii

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Contents

3.4.2 Axle Load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Real Axle Loads in a Semitrailer. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Problem of Axle Loads with Tractor-Semitrailer-Combination. . . . 3.4.5 Unloading and Axle Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.6 Solutions to the Axle Load Problem . . . . . . . . . . . . . . . . . . . . . . . . Payload and Curb Weight of the Entire Vehicle. . . . . . . . . . . . . . . . . . . . . . Emission Regulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.1 Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.2 European Test Cycles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.3 US Emission Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.4 On Board Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.5 Greenhouse Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.6 Future Development of Exhaust Emission Standards . . . . . . . . . . . Type Approval in Europe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.1 Safety Regulations in the U.S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Driving Resistance and Longitudinal Dynamics. . . . . . . . . . . . . . . . . . . . . Lateral Dynamics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.1 Comfort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.2 Ride Comfort. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33 34 36 37 38 39 40 40 41 42 43 43 44 45 46 47 50 52 53

Comprehension Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Abbreviations and Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3.5 3.6

3.7 3.8 3.9

1

Introduction

Commercial vehicles move nearly 11 billion tons of freight in the United States every year [12]. 15 years ago, commercial vehicles already transported about 100 kg of goods per day for every inhabitant of Germany [24]. And despite the social consensus that we all try to reduce our ecological footprint, one can safely assume that this number is higher nowadays. The transported goods include finished products that consumers see directly, such as bread for your sandwich, but also intermediate products that are used to make the finished products, such as the flour delivered to the baker several days earlier. Refuse vehicles then regularly collect trash, scrap paper and organic waste. The free availability of goods depends on road-based goods transport using trucks and transporters (Fig. 1.1). Commercial vehicles contribute significantly to our high standard of living. Our goods are also transported by rail and inland watercraft, but only the commercial vehicle, which can travel on roads, has a network that is extensive enough to meet our supply needs. Do you know of a supermarket with its own railhead? Transporting goods by commercial vehicle is also very efficient. Technically, trains travel at the same speed or even faster than commercial vehicles. With that said, the average speed by rail from the shipping point to the recipient by rail are discouragingly slow in nearly every country. On the other hand, over long distances and when the goods involved are non-perishable, non-urgent, bulky and/or very heavy, the advantages of transporting by rail or barge are undeniable. The intercontinental traffic of goods that characterizes our globalized economy is assured to a large extent by large sea-going ships. The global flow of goods is continuously increasing—as can be seen in Fig. 1.2. And global trade in goods by container also needs trucks at both ends of the chain. At the beginning and at the end of the transport chain, there are trucks needed to take the container to where the goods are finally loaded and unloaded—see Fig. 1.3.

© Springer-Verlag GmbH Germany, part of Springer Nature 2023 M. Hilgers, Entire Vehicle, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-67070-5_1

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Fig. 1.1   Trucking moves america forward campaign, american trucking association

Fig. 1.2   Container throughput worldwide between 2000 and 2016

1.1 History The truck is almost as old as the car. It was logical to extend the advantages of the automobile to move goods as well. The first truck was built by Daimler-MotorenGesellschaft in Cannstatt, Germany in 1896, 10 years after the first appearance of the car [13]. The vehicle had a payload of 1.5 tons (t) and an unladen weight of 1.2 t. Driving power was supplied by a 4-hp, two-cylinder engine [14]. None of those first trucks exist today. Figure 1.4 shows a commercial vehicle which was produced two years later, which is now the oldest commercial vehicle still in existence.

1.1 History

3

Fig. 1.3   In global container traffic, trucks are an indispensable element of the transport chain. Containers are usually moved by trucks at the beginning and at the end of the goods transport process

The first trucks were intended for use in agriculture, as is revealed in this advertising copy produced by the Daimler-Motoren-Gesellschaft for the Cannstatt Festival of 1897: A Daimler is a useful beast, it pulls like an ox as all can see; It eats no hay at the end of the day and only drinks when work is going well; it threshes and saws and pumps for you, and will work when cash is tight, as often happens; It never suffers from foot-and-mouth and does not play mischievous tricks. It does not answer back in anger, it will not consume your precious corn. So buy yourself a workhorse like this, and you will want for nothing more.

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Fig. 1.4   The oldest truck powered with an internal combustion engine still in existence, produced in 1898. The engine is located under the driver’s seat and the cargo area (underfloor). With a displacement of about 1.51 it delivered approximately 5.6 hp (4.1 kW). It was capable of carrying a payload of 1250 kg. The vehicle is on display in the Mercedes-Benz Museum in Stuttgart, Germany. (Photo: Michael Hilgers)

However, the advantages of the truck were also very soon recognized by other companies wanting to transport heavy goods quickly and reliably—such as breweries1 or flour mills. Nowadays, trucks have made their mark in every last corner of the world.

1.2 A Few Terms A great deal of effort has been expended in defining various terms for regulations and standards. I try to avoid that. But it is helpful to define exactly what is meant by some terms from the outset. This is my short version: • A vehicle is anything that travels. • A motor vehicle is a vehicle with its own source of driving power which is not restricted to a track (no rails, etc.). • An automobile (motor vehicle) is a multitrack motor vehicle (a motorcycle, e.g., motorbike is single-track).

1 One

is reminded of the imposing brewery drays pulled by as many as six horses, which had to be fed, groomed and trained!

1.2  A Few Terms

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• Trailers are vehicles without their own drive system. • Semitrailers or semi-trailers are trailers whose considerable portion of the weight is supported by the tractor vehicle and that are connected to the tractor by a fifth wheel coupling. • Tractors are motor vehicles which pull a trailer. • A commercial vehicle is designed for the commercial transport of passengers or goods and has a permissible gross vehicle weight of more than 3.5 t.2 • Goods vehicles are commercial vehicles which are used for the transport of goods. All other terms will (hopefully) be explained by the text.

1.2.1 The Coordinate System In engineering we need a coordinate system. In this book, the coordinate system is fixed relative to the vehicle, as shown in Fig. 1.5: The direction of travel is the positive x-axis. The z-axis is perpendicular to the ground plane and points upwards. Since we technology professionals use the conventional, three-dimensional, right-handed coordinate system, the y-axis is fixed: The y-axis is projected parallel to the axles of the vehicle. The positive direction of the y-coordinates progresses from the right to the left side of the vehicle viewed in the direction of travel. This coordinate system is widespread in the technical literature. The co-ordinate system is defined like this in ISO70000 and ISO8855 superseding DIN70000. SAE J670 defines this kind of co-ordinate system as well and calls it the “z-up” system. In SAE J670 an alternative coordinate system is offered as well (z-down). ISO4130 defines a co-ordinate system with a different orientation (x-axis points backwards). In technical discussions it is advisable to clarify first which co-ordinate system is used. Our co-ordinate system is shown in Fig. 1.5 For rotational movements about the axes, the following technical terms are used: rotation about the vertical axis (z-axis) is called yaw, rotation about the longitudinal axis of the vehicle (x-axis) is called roll and when the vehicle rotates about the y-axis, we refer to it as pitch.

2 According

to this definition, taxis in the form of cars are not commercial vehicles.

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Fig. 1.5   Coordinate system as used in commercial vehicles: The x-direction is the direction of travel of the vehicle. The axis that projects vertically is the z-axis and the y-axis is determined consequently as projecting transversely to the vehicle, from the right side to the left

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Trucks as Investment Goods

The range of activities in which trucks are used is enormous. And wherever they are used, all of these activities share a common element: the truck is an asset used to earn money, either directly or indirectly. The traditional carrier earns its money directly from moving freight, using a truck as an asset. In the vocational segment, businesses make money providing a different service, in which the truck is only the instrument to deliver the service. Examples of this would be a mobile concrete pump, a roadsweeping machine, a refuse collection vehicle, or a crane mounted on a truck chassis. The gardener or tradesman who drives a truck also belongs in this category. In these cases, the end product is not the transport of goods; but without the truck it would be incalculably more difficult to deliver the requested service. In this case as well, the truck falls under the heading of an asset. The huge variety of tasks involving the use of a truck has led to the development of a plethora of specialized vehicle models, designed specifically to carry out a respective task. The various vehicle manufacturers already produce a considerable number of different vehicle types. Specialization is then further refined by the truck equipment manufacturer, sometimes also called body builder, who installs the body on the manufacturer’s road-ready vehicle. Sometimes the body is much more expensive than the basic vehicle. See also [11].

2.1 The Application The enormously-varied range of applications the truck is expected to perform is reflected in the variety of different vehicles.

© Springer-Verlag GmbH Germany, part of Springer Nature 2023 M. Hilgers, Entire Vehicle, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-67070-5_2

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Fig. 2.1   Examples of various applications in highway, vocational and medium duty market segments

Certain applications require highly specialized vehicle bodies, or trailers. For example, there are tankers for petroleum products as well as for food, vehicle carriers, cement mixers, road sweepers, construction material transporters with loading crane, logging trucks, dumpers, container trucks and many more (Fig. 2.1). The closest thing to a standard vehicle is the tractor-trailer combination. A tractor pulls a number of different trailers and so it offers a certain amount of flexibility. This is why in the US as well as in Europe and China, tractor-trailers account for the largest percentage of new vehicles in the heavy commercial vehicle segment. The proportion of vehicle registrations of tractor-trailers is growing. The standard semitrailer is a trailer with tarp or box body. More and more tractor-trailer combinations are also used on construction sites, pulling semitrailers with a dump box. Besides the load that is actually transported, the application is also defined by other criteria, for example, the route: Does the load have to be transported through the city or hauled over long distances on major roads? Is the route flat and undemanding or is it hilly? Perhaps the vehicle must even travel off-road? Both the load and the transport route are being considered to find the best vehicle configuration and successfully complete the transport task as economically as possible. This brings us neatly to the next section in which we talk about profitability.

2.2  Profitability of the Commercial Vehicle

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2.2 Profitability of the Commercial Vehicle The purpose of a commercial vehicle is to earn money. The profit is calculated by subtracting costs from income. Therefore, the vehicle operators wants a vehicle that enables them to perform many, well-paid transport tasks all the while incurring the lowest possible costs.

2.2.1 Optimizing Income The correct vehicle and vehicle equipment help the carrier or vehicle operator to increase his income. There are operations that must be billed according to the mass of the cargo transported. These may involve bulk materials or construction materials (cement truck). The right vehicle for these tasks is a payload-optimized vehicle with low unladen weight in which the carrier can transport the largest possible (paid) quantity of cargo. Other operations are paid according to volume, so in these cases the carrier is interested in being able to transport the greatest volume possible. For this, there are vehicle concepts which maximize freight volume, such as low-frame vehicles (lowliners), extended length semitrailers (special permit required) or articulated trains with lowmount coupling systems (see [11] and Chapt. 3, Fig. 3.3). Since the carriers can generate additional income with each trip, it is in their best interest to complete individual load assignments as quickly as possible. Here, too, they are helped by vehicle technology: Semitrailer and bodies that are optimized for the cargo in question facilitate fast loading and unloading, so the vehicle is soon back on the road again. Navigation systems reduce out-of-route miles and help the driver to choose the quickest route or avoid traffic jams. Depending on the situation, it may be worth opting for high engine power so that the resulting high average speeds enable a high customer turnover for the operator or to take on heavy hauls. Wear-free permanent brakes (retarders), which enable safe downhill driving, might help drivers to achieve higher transport speeds. Another highly effective optimization strategy is to avoid empty runs and to transport return cargo whenever possible. When (paid) cargo is transported on both the outbound and the return journeys, this is called backhauling. If this does not happen, it is called deadheading. Vehicle technology helps to move the vehicle with loads on both the outward and return journeys as often as possible, for example, by using the above-mentioned flexible semitrailer that are suitable for various types of cargo. Another way to optimize revenue is to specialize. If a transportation company gains a reputation as a specialist in certain tasks, it becomes easier to receive orders in this segment. It also happens that in certain segments of goods transport, the cargo rates that can be commanded may simply be higher than in other segments. Specialization may be

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associated with the goods that are being transported (fresh products, heavy loads) or with certain destinations. Finally, certain soft factors that can contribute to revenue optimization should also be mentioned: A visually appealing vehicle fleet may convince more prospects to decide to work with a given transportation service provider. A modern vehicle—perhaps even of a certain brand—can enhance a company’s image and indicate that the customer has found a highly capable contractor. This effect is as important for the gardener or tradesman whose customers are the end consumer as it is for multinational freight forwarding companies that wish to project a vital, high-performance organization.

2.2.2 Costs Besides optimizing income, the second approach is to reduce the costs of operating the vehicles. Expenses of a long-distance haulage company are listed in Fig. 2.2. Figure 2.3 shows a comparison of the various cost elements. The breakdown of costs shown here represents a sample of motor carriers in North America over a five-year span using a conventional diesel powered truck. The cost structure varies based on industry sector, size of fleet, type of operation, region and average age of equipment. The distribution of costs also changes constantly due to relative price fluctuations over time, particularly in driver wages and benefits, and fuel. Different trucking companies may have different cost ratios, even if they hauls similar freight.1 Driver wages and benefits The driver accounts for a large portion of the total costs. Driver costs include wages, benefits and bonuses. In some countries (like the US) driver salary has increased a lot over the last years (decade). This is primarily due to an aging demographic and a continued shortage of qualified drivers. In Europe the level of salaries varies significantly between different European countries, so the cost portion of driver’s salary differ between countries. As in Europe the transport companies compete with each other across national borders, companies might have some cost advantages or disadvantages depending on the country they are operating from.

1 Example:

A fictitious transportation company A attaches great importance to the latest technology and well-trained drivers. Fictitious transportation company B pays its drivers less, and they are therefore less well trained, change employers more frequently and take less care to drive in a way that conserves materials. Company A will presumably have somewhat higher expenses for the driver and depreciation, whereas company B will spend more money on fuel, repairs and maintenance. Both companies may transport the same goods and both can operate successfully on the market.

2.2  Profitability of the Commercial Vehicle

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Mileage-related depreciation (wear and tear) Fuel costs

Variable costs

Other operating materials (DEF*, windshield washer fluid, etc.)

Costs of vehicle operation

Lubricants (oil and grease) Maintenance and repair (incl. replacement parts) Vehicle cleaning Cost of tires Mileage-related road use (tolls) -- Other -Expenses

Driver costs

Surcharges Social security payments

Vehicle fixed costs

Wages Time-related depreciation Third-party financing costs (interest, leasing payments)

Cost of vehicle ownership

Road tax Time-related road use fee (vignette, or road tax) Insurance Inspection fees Parking costs

Company fixed costs

Administrative personnel costs Office rental

Administration costs

Office materials, communication costs, etc. Insurance (non-vehicle related) Contingency costs (payment default, uninsured damage, etc.) Consultancy costs, premiums and commissions -- Other --

Imputed employer's salary

Fig. 2.2   Expenses contributing to the total cost of a long-distance haulage company (*DEF = Diesel Exhaust Fluid)

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Fig. 2.3   Breakdown of motor carrier operational costs in the US according to [15]

Loss of value, depreciation In typical long-haul businesses, the procurement costs, or the loss of value (depreciation) of the vehicle does not represent a dominant part of the total costs. Loss of value consists of a time-dependent component (the vehicle ages) and a usage-dependent component (the vehicle wears out). The residual value that can be recouped at the end of the planned useful life of the vehicle reduces the degree to which procurement costs play into the total costs situation. In total, the procurement price of the truck is not a dominant factor in the total cost consideration over its entire service life.2 Of course the costs for the body, which on vocational vehicles may be several times greater than the vehicle costs, must also be taken into account. Financing costs Besides the loss of value the vehicle undergoes, the interest and charges the carrier has to pay to purchase a vehicle must also be considered. If the vehicle is paid for directly from company capital, without financing, imputed interest must be taken into account to reflect the fact that the money might have realized a profit if it had been used elsewhere. For example, instead of buying the truck, the company could have left the cash in its bank account and reaped the benefits of the interest. These are also referred to as opportunity costs. Repairs and Maintenance In a typical motor carrier, maintenance and repairs make up a single digit percentage (up to maximum 10%) of total costs. Repairs and maintenance costs fluctuate in proportion to vehicle utilization. The more intense and the longer the vehicle is utilized, the greater 2 In

this context, one often speaks of Total Cost of Ownership (TCO). This describes the total costs over the period of use of the vehicle.

2.2  Profitability of the Commercial Vehicle

13

the wear and tear. Both cost types can also be significantly influenced by the driver. A driver who drives smoothly subjects the equipment to less stress, thereby reducing both maintenance and repair costs. Accidents for which the driver is responsible are reflected directly in this cost category. Various driver assistance systems designed to reduce the likelihood and seriousness of an accident have the capability to lower repair costs. Lastly, a labor shortage of repair technicians in the United States have also driven up repair costs over time. The vehicle owner can also enter into a service contract instead of having to include the maintenance costs in his cost calculations. These service contracts are offered by the vehicle manufacturers and provide customers better certainty. Then, instead of the maintenance costs, the cost calculation must reflect the costs of the service contract as well as any costs were not covered by the service contract. In the event of unscheduled repairs, additional costs may arise besides the costs of the repair, such as the cost of a replacement vehicle. Tires Tires represent an astonishingly significant expense for the truck company. They become worn and must be replaced in good time. Unfortunately, the individual tire is quite expensive, and many of them are needed all at the same time: In e.g., the US and China the 6 × 4 standard tractor semitrailer combination needs ten tires for the tractor and and another four or six tires for the semitrailer, and possibly a complete set of winter tires. In Europe the more common 4 × 2 tractor still needs six tires. And tires not only represent a cost factor in and of themselves, they also affect the fuel costs [8] through rolling resistance. Vehicle insurance and road tax For the sake of completeness, insurance and road tax expenses are also listed here. The good news is that the associated costs are easy to calculate. They are unavoidable. At the same time, road tax is fixed nationally, so it differs from one country to another. Fuel consumption Fuel consumption represents the second largest cost in long-haul operations (see Fig. 2.3). As a result, reducing fuel consumption of vehicle operations is of particular interest amongst fleets. That is why an entire book in this series is dedicated to the topic of fuel consumption [8]. The fuel costs are to a substantial extend determined by fuel tax. In the US the fuel tax is not only a cost factor but also adds to the administrative tasks of a freight forwarder: Excise taxes are paid on both the federal and state level for fuel consumed by all motor vehicles. The revenues raised from taxation largely fund the maintance and buildup of transportation systems inlcuding highways and bridges the vehicles use. Commercial vehicles have large fuel capacities and travel across several states between fueling. This situation poses problems, since the collection of taxes and the use of roads

14

2  Trucks as Investment Goods

often occur in different states. To ensure the collection of state tax revenues is distributed to states where the roads are used, motor carriers are required to submit fuel tax reports. The reports detail the miles a vehicle drives state by state to determine where to distribute tax revenue. This mechanism ensures highway funding is proportional to road use. Ultimately, the most critical figure for the carrier is the specific fuel economy, or freight efficiency, per transported unit. If the carrier reaches the load limit for his vehicle, consumption per transported unit of weight is the parameter of interest. Freight efficiency is typically expressed as ton-kilometers per liter (in Europe) or ton-miles per gallon (in the US). However, there are also loads in which the vehicle has not reached its limits in terms of transport weight but rather volume. When assessing these kinds of transport tasks, the decisive value is consumption per transported cubic meter of capacity. Fully utilizing all available cargo volume is known in the US as cubing-out. To improve the freight efficiency, long combination vehicles are from time to time a topic of discussions in fuel consumption optimization and CO2 reduction. Besides fuel, the truck also consumes engine oil, lubricants and—if it conforms to modern emission standards—Diesel Exhaust Fluid.3 Besides the above, windshield washer fluid also has to be added according to consumption, and coolant according to the maintenance schedule. However, compared with the cost of fuel, these consumables are practically negligible. Road use charges, toll In some countries, e.g., most European countries, Japan, China, trucks—and in many cases cars—must pay a distance-dependent charge for using parts of the highway network. This toll might represent a quite substantial portion of the total costs of long-distance haulage. Other countries do not charge toll for road usage directly. Substantial tax income from road users is (additionally to toll) generated by fuel tax. Safety, comfort and cost Safety systems may be designed to reduce a vehicle operator’s costs. Most accidents lead to repair costs and a reduction in the vehicle’s value. Additional costs also arise, such as extra costs for a replacement vehicle, and in the worst case if the driver is injured, health care costs and the cost of a substitute driver. Accidents for which the driver is responsible lead to an increase in insurance costs. An accident also negatively impacts the carrier’s adherence to delivery dates and thus also customer satisfaction. Comfortable vehicles can help to reduce costs for similar reasons to safety systems. If the driver is rested and driving in a comfortable vehicle, he or she will drive more safely,

3 Diesel

Exhaust Fluid (DEF) is an aqueous urea solution which is stored in a separate tank in the vehicle and injected into the exhaust system to extract the pollutant nitrogen oxides from the engine exhaust in the catalytic converter and convert them into water vapor and harmless nitrogen.

2.4  Profitability and Cost Structure for Autonomous Driving …

15

and statistically should be involved in fewer accidents. But the more important argument is that the driver of a comfortable vehicle is more relaxed and drives more smoothly and more attentively, which is more fuel efficient, and consequently generally more economical. Experience has shown that many drivers not only take better care of vehicles they like but also drive them more carefully.

2.3 Profitability and Cost Structure for Alternative Propulsion Systems Driven by climate change and the need for propulsion systems that do not emit greenhouse gases, alternative drivetrains will be used in the future. Currently we can consider the freight forwarding business in the developed countries in a transistion phase between the conventional diesel fuelled commercial vehicle and new, alternative drivetrains. The most promising candidates here are battery electric vehicles and electric drivetrains that produce electricity onboard via a fuel cell using hydrogen [9]. No matter what the drivetrain is, the basic need of the freight forwarding company to run a profitable business is unchanged. On the income side there might be some subsidies (especially in the initial phase) for the freight forwarding companies using alternative drivetrains. Some customers might be willing to pay a little more for the green technology used. For sure, income must exceed costs to keep the freight forwarder alive. The basic costs categories as shown in Fig. 2.2 will remain for alternative drivetrains. However the relative contribution will change. Especially initial price of the vehicle and cost of fuel can be expected to take a different share than in today’s cost split-up. From experience in the passcar segment one can expect that maintenance and repair costs might actually be lower for alternative propulsion systems.

2.4 Profitability and Cost Structure for Autonomous Driving Trucks Not only the new drivetrain technologies as mentioned in the section above but also the strive for fully automated driving trucks (autonomous trucks) changes the cost structure of the business. The autonomous truck requires more and more expensive technology in the truck [5]. It will probably also require a more powerful infrastructure, such as a control center that monitors the truck and can intervene if necessary. On the other hand, driver costs are (largely) eliminated. Further cost contributions, which can develop advantageously, are the fuel consumption and also the maintenance costs of the basic vehicle. An autonomous truck can be operated fuel-efficiently and perhaps more slowly (saving further fuel). Another component in the profitability of the autonomous vehicle is that the vehicle can drive virtually around the clock. The technology does not need rest periods like the human driver. It is generally assumed that on many long-distance routes,

16

2  Trucks as Investment Goods

autonomous trucks will be much more economical than today’s trucks when the autonomous technology is established and reliable. So in trucking business the motivation for autonomous systems is driven by economical considerations. This is different from the passenger car world where in most cases it is more a convenience system.

2.5 Trucks from the Driver’s Perspective Apart from the perspective of the motor carrier, who considers the truck as an investment and a machine for earning money, the (non autonomous) truck must also meet the needs of the driver. The driver spends many hours in the vehicle and often forms an emotional bond with it. Since good drivers are important to the freight forwarder and should be encouraged to stay with the company, it is important for the vehicle to satisfy the driver’s requirements as well. Or, to put it bluntly, the truck manufacturer has two customers: the freight forwarder, i.e., the purchaser, and the driver, i.e., the user! The driver’s assessment of their vehicle is particularly important in long-distance haulage. In long-distance haulage, apart from purely driving time, the driver often also remains in the vehicle during moments of free time, recreational phases and sleep. The cab serves as both living and sleeping quarters [10]. According to various studies (for example, [16]), it is becoming more and more difficult to find people who are interested in a career as a truck driver. In view of this trend, it is all the more reason to address the driver’s needs regarding the long-haul vehicle. Many freight forwarding companies take into account drivers’ opinions on different vehicles and equipment variants when considering the purchase of new vehicles. Moreover, as a result of demographic changes and the increasing age of drivers, it is becoming increasingly important to ensure that vehicles and trailers, or bodies, are ergonomically optimized and can be operated with minimum physical effort. In distribution haulage, the vehicle is usually less important to the driver, since it is perceived solely as a piece of equipment. The driver does not sleep and live in the cab. The driver’s right to express opinion regarding the purchase of vehicles is usually less important to the freight forwarding company. Even so, the vehicle manufacturers go to great lengths to accommodate drivers’ needs as diligently as possible in distribution vehicles.

2.6 Customer Purchasing Criteria In summary, the criteria the customer applies when choosing the right vehicle falls into three groups—similarly to the three Sects. 2.1, 2.2 and 2.5 above: the suitability of the vehicle for the specific transport task, consideration of the total costs over the service life of the vehicle and soft factors.

2.6  Customer Purchasing Criteria

17

Vehicle Ancillary criteria • Financing offer

• Brand loyalty • Consulting and customer support by the salesperson

• Manufacturer's workshop network • Own workshop's expertise • Availability of replacement parts

TCO of the vehicle • Fuel consumption • Purchase price and projected resale price • Costs of repair & maintenance

Safety • Comfort • Driving feel • Appearance/Appeal and design

Suitability of the vehicle for purpose • Volume • Payload • Suitability for special body • Off-road capability E m nvir co enta onm bil pa l ity ti-

Soft factors Fig. 2.4   The criteria a customer applies when purchasing a truck can be summarized in three groups: total costs over the period of use (TCO), suitability for the intended transport task and soft factors such as comfort. Besides these three groups of criteria, which directly describe the vehicle, the decision to purchase is typically influenced by other, more broadly related factors such as the workshop network

Figure 2.4 illustrates these three groups and lists the most important specific purchasing criteria. It is of course possible that the relative importance of the criteria may vary for different purchasing decisions. Besides the criteria relating directly to the vehicle, there are other criteria that can significantly affect the decision to make a purchase. These are, for example, the workshop network, the customer’s own ability to repair a given brand, or even interpersonal criteria such as the relationship between the buyer and the truck salesperson.

3

Entire Vehicle

The vehicle manufacturers normally organize their development areas according to their assemblies. There is one area dedicated to the engine, another which makes the axles or develops the cab, and so on. The supplier landscape has also evolved over decades to reflect a breakdown of the vehicle according to assemblies and components. Wellrespected companies have cultivated their core competence in, for example, vehicle electronics or transmission building. And this logical and traditionally usual separation organization of the vehicle into assemblies is also reflected to some degree in this series of booklets [4–7, 9, 10]. However this chapter is concerned with the vehicle as a whole. The customer buys an entire vehicle and expects it to have certain characteristics and be suitable for use in certain situations. For the user of the vehicle, the commercial benefit of the vehicle is of utmost importance—as the name commercial vehicle implies. The vehicle is evaluated in its entirety and is perceived by the customer as such. The customer is primarily interested in whether the vehicle is able to carry out the intended transport task. While the engineer takes great pleasure in the individual technical refinements, the customer often finds them irrelevant. A truck consists of several thousand parts, as is illustrated in Fig. 3.1. These must all fit together to form an efficiently functioning entire vehicle. What the individual assemblies and component parts are expected to contribute can be derived from the requirements the entire vehicle must satisfy and its intended purpose.

3.1 The Vehicle Concept The vehicle concept defines the basic mechanical concept, the dimensions and the positioning of the components in the vehicle. The cab concept is visually striking in particular: conventional or cab-over-engine? This question, or at least the question of which cab © Springer-Verlag GmbH Germany, part of Springer Nature 2023 M. Hilgers, Entire Vehicle, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-67070-5_3

19

3  Entire Vehicle

20

4x2 standard tractor

Parts to be installed*

1000 1000 2000

Front and rear axle Transmission Engine

3200

Cab

4500

Chassis

Approx. 12,000

Different parts

8x8 all-wheel drive dumper

Parts to be installed*

5000 300

500

700 1600

Different parts

Driven front and rear axles and through-drive

1000 1500

Transfer case

2000

Engine

2600

Cab

7000

Chassis

1500

300 600

Transmission

700 1350

1600 1900

Approx. 4,700 Approx. 19,000

Approx. 6,500

* Number of parts to be installed from the point of view of the OEM. Many components are delivered as pre-assemblies by the supplier. The number of parts hence depends on the OEM's vertical integration.

Fig. 3.1   Estimated number of parts from which a truck is built in the vehicle manufacturer’s factory. Components that are delivered to the vehicle manufacturer (OEM) as assemblies are considered as single parts, even if the assembly itself consists of many individual components, for example, the seat. Some parts are installed in several different positions. Therefore, the figure also shows how many different parts are assembled to build the truck. The number of parts for a three-axle tractor is in between the 4 × 2 and the 8 × 8 with approximately 13,000 parts (not shown)

predominates in a given region, is heavily influenced by legal regulations. This will be discussed later (Sect. 3.3). Despite the enormous variety of available vehicles and the fact that in some cases commercial vehicles have been massively adapted for their specific work purpose, some basic constants can be found in (nearly) all the concepts used for modern commercial vehicles: Trucks have a ladder-type frame as the supporting structure. In North America, a cab is mounted on the frame with an isolation system just behind the engine. In other regions, a sprung cab is mounted on the front of the frame just over the engine. The useful area is in the rear. The drivetrain arrangement is the same in all trucks: all trucks have a front-to-rear installation, the engine is mounted in the front, which is the best position for cooling, and drives at least one rear axle, or sometimes several axles. The engine crankshaft runs parallel to the longitudinal axis of the vehicle. The transmission

3.1  The Vehicle Concept

21

is mounted behind the engine. Other vehicle concepts such as front-wheel drives, transverse-mounted engines, underfloor engines and transaxle configurations are not used at all in trucks. The bus manufacturing industry is different in that they can have many different drivetrain configurations. In the standard large European bus the engine and transmission are mounted behind the rear axle; and the engine can be mounted lengthwise or transversely. The rear engine placement is favorable for configuring the driver cockpit and the access options for the passengers and can be adapted well to the passenger area. By its nature, the cooling of the engine is a bit more complicated. In small buses, the engine is often located at the front like a truck. All trucks and buses have double-pivot steering (Ackermann-steering).

3.1.1 Tractor Unit or Truck Very roughly in truck transport, two transport concepts can be distinguished: First, the semitrailer tractor, which does not have its own loading area or other “usable cargo area” of its own. The tractor is designed to pull a semitrailer and is only suitable for transporting goods in combination with this semitrailer. Secondly, there is the truck with loading area or superstructure. The truck can additionally pull a trailer behind it and then becomes a so-called articulated train. Figure 3.2 shows the two concepts for Europe and the US. Both concepts have their specific advantages: With the standard dimensions in Europe, the articulated train offers a larger transport volume and three additional Europallets (base area 80 cm × 120 cm) can be loaded than with the semitrailer. In the case of the articulated train with central axle trailer (Fig. 3.3), the volume advantage over the semitrailer is even greater. The semitrailer tractor, on the other hand, has the advantage that it offers a larger payload. It is also more economical in terms of fuel consumption. The semitrailer tractor can also be very flexible in its use: It can be easily coupled to different semitrailers. The cargo truck with trailer requires significantly less space both for forward and reverse travel while cornering—at least with a short towbar. The semitrailer to the contrary swings out very significantly while cornering both front and rear, thus requiring a large amount of space. However, the semitrailer is much easier for less experienced drivers to maneuver in reverse. Ultimately, the market decides: it shows a clear preference for the semitrailer tractor. There are significantly more semitrailer trucks on the roads than articulated trucks. In many investment decisions, the higher payload of the semitrailer combinations combined with a lower system price seems to win the argument.

22

3  Entire Vehicle

Fig. 3.2   Sketches of tractor with semitrailer and articulated train. Upper part: Dimensions for standard trucks in Europe. The regulation is strongly influenced by maximum permissible lengths. Lower part: Legally regulated outer dimensions in the United States. In the US the so-called bridge formula plays an important role (see sect. 3.3.2).

3.1  The Vehicle Concept

23

Fig. 3.3   Articulated train with central axle trailer. This configuration makes it possible to realize a large transport volume. This configuration is mainly used in Europe; and even there it is a niche product. 

3.1.2 Vehicle Configuration and Operating Case Besides the basic choice between a tractor-semitrailer combination and a truck-trailer, the carrier’s decision for the right vehicle is determined by many other parameters as well: • The cargo the vehicle is intended to carry (the nature of the cargo and the total load capacity). Obviously, a vehicle for transporting lumber or logs should be configured differently from one that will spends its operating life making deliveries to newspaper stands in the heart of the city. • The terrain the vehicle will have to negotiate. • The condition of the infrastructure within its operating range. • The climatic conditions in which the vehicle will operate. • The length of the routes and the total annual mileage planned for the vehicle. • The amount of traffic and routes it will travel (Are there many bends? How often will the vehicle accelerate and brake?) The congestion in Asian conurbations is undoubtedly one of the reasons why a typical light-duty truck is much more widespread there than in Europe or the US. • The customer segment the vehicle is intended to address. • The legal provisions in the countries where the vehicle is to be registered and operated. [20] shows examples of how the various parameters of vehicle usage are considered in order to assemble the right vehicle for the customer.

24

3  Entire Vehicle

Fig. 3.4   Reference values for the yearly mileage, total mileage in lifetime of commercial vehicles in various segments. Truck speeds in the US are somewhat higher than in Europe. 1 mile = 1.609 km

Period of use, average speed and product service life can greatly differ according to the segment in which the vehicle is used. Figure 3.4 illustrates the vastly different usage profiles of motor vehicles with reference to operating years and miles traveled.

3.1.3 Effects of Production on the Vehicle Concept Besides the determinations that are of importance for the user, the vehicle manufacturer makes additional concept decisions while developing the vehicle. These include production-driven considerations which do not affect the customer. One important criterion for production is that it must be possible to manufacture the vehicle inexpensively and reliably. Some vehicles and their production concepts are produced in low volume and as a consequence the technical product concepts might differ from vehicles that are produced in large numbers. The vehicle manufacturer also ensures that an additional product is compatible with its own product portfolio and shares as many common parts with the existing products.

3.2  Vehicle Variants

25

3.2 Vehicle Variants 3.2.1 Axle Formulas The axle formula describes how many axles the vehicle has and what functions the axles perform. The first digit in the axle formula indicates how many wheels or dual wheels the vehicle has. The second digit indicates how many of the wheels are driven. A slash is then followed by the number of steered wheels. A vehicle with wheel formula:

8 × 4/4

(3.1)

has eight wheels or dual wheels, i.e., four axles. Of these, two axles are driven and two are steered. Letter combinations give additional information: • • • •

NLA described a trailing axle. DNA stands for a trailing axle with dual wheels. ENA stands for a trailing axle with single wheels. VLA is the leading axle.

Figure 3.5 shows various axle configurations. Other axle configurations are conceivable. A fifth axle, which is becoming more and more popular further increases the number of possible axle formulas.

3.2.2 Geometry of the Vehicle When defining the entire vehicle, the outer dimensions of the vehicle are important features. The boundary conditions, which must be complied with, are derived from the legal provisions set forth in Sect. 3.3. However, there are a lot of other dimensions which differentiate the vehicles. These include, for example, the wheelbase, the distance between the rear axle and the fifthwheel kingpin, the tire size and the frame track. Other typical dimensions which are of particular relevance for off-road vehicles are, for example, the overhang (front and rear), the angles of approach and departure, the ramp breakover angle and ground clearance. These are illustrated in Fig. 3.6.

3  Entire Vehicle

26

4x2

6x2 VLA

4x4

6x4

6x2

6x6

steered

with dual wheels

unsteered

with single wheels

driven

not driven

8 x 4/6 ENA

6 x 2/2 DNA

8 x 2/4 ENA

6 x 2/4

8 x 2/6 ENA

8 x 6/4

6 x 2/4 NLA

8 x 4/4 ENA

8 x 8/4

8 x 4/4

Fig. 3.5   Examples of various axle configurations

3.3 Dimensions The legal provisions that have the greatest influence on the visible concept of a truck are undoubtedly those which stipulate the dimensions and permissible weights of the vehicle (gross weight and axle loads). Vehicles look different in size and vehicle layout in Europe, the US and elsewhere because of differences in legal requirements.

3.3.1 Dimensions in Europe The maximum dimensions and masses authorized for a vehicle under the law are defined for Europe in Directive 96/53/EC. Particularly with regard to the weights and axle loads, 96/53/EC makes allowance for differing regulations for traffic limited to the territory of one member state. The height of the vehicle can also be varied by individual

27

3.3 Dimensions

Max. body length

Front overhang

Approach angle

Wheelbase

Ramp breakover angle

Rear overhang

Ground clearance

Departure angle

Overall length

Fig. 3.6   Angles of approach/departure and ramp breakover angle, shown here on a light truck with four-wheel drive. This illustration is based on [22]

member states. Further specifications regarding masses and dimensions are set forth in Commission Regulation EU 1230/2012. The permissible dimensions of a vehicle are specified in Directive 96/53/EC as follows: The maximum length of a truck must not exceed 12 m. The maximum permissible length of the trailer is also 12 m. The total length of a truck with trailer—a “drawbar combination”—must not exceed a length of 18.75 m. Accordingly, a trailer with the maximum dimension must not be coupled to a truck with a length equal to the maximum permissible length of 12 m, because the length of the combination would then exceed the maximum permissible combination length of 18.75 m. The “system length”, that is to say the distance from the front edge of the cargo area to the rear edge of the cargo area may be up to 16.4 m for drawbar combinations. Figures 3.2 and 3.3 illustrates the permissible lengths. The maximum width of a truck and the trailer is 2.55 m. Exterior mirrors or protruding clearance lamps are not considered for assessing the width. They are allowed to stand out further, and usually they do. The permissible width of refrigerated vehicles is fixed at 2.60 m. This regulation was put in place so that refrigerated vehicles could transport two Euro-pallets side by side in the transverse direction of the vehicle or three Euro-pallets side by side in the lengthwise direction of the vehicle and still leave enough wall thickness to allow effective insulation to be installed. The maximum height of a truck or trailer under European rules is 4 m. For national traffic different height restrictions are possible and are actually in place. The same restrictions regarding height and width also apply for tractor/semitrailer combinations. The length of a semitrailer combination has been set at 16.5 m. Tractor/ semitrailer combinations are only allowed to be this long if the distance from the kingpin

28

3  Entire Vehicle

(the pin that attaches the semitrailer to the fifth wheel coupling) to the rear end is less than 12 m and the overhang radius from the kingpin to the front corners of the semitrailer is less than 2.04 m. If these conditions are not met, the permissible total length of the tractor/semitrailer combination is limited to 15.5 m. Since 2015, the European legislator has permitted vehicles in intermodal transport (sea containers) that are longer than the standards semitrailers by 15 cm [25]. This makes it possible to transport 45-foot containers, which are increasingly being used. In some European countries (e.g., Sweden), longer (and heavier) trucks are approved nationally. So-called long trucks are up to 25.25 m long. The most common configuration consists of a motor vehicle with a loading area, which pulls a so-called dolly as a drawbar trailer. The dolly carries a fifth wheel on which a standard trailer is mounted. Those vehicle combinations are referred to as gigaliner, eurocombi or ecoliner; more names can be found.

3.3.1.1 New Length Regulation in Europe As stated above, in Europe the total length of a truck and the “system length” i.e. the loading length are both limited. This has basically created standard dimensions for a long haul cab in Europe: In the last decades and up to now (early 2020s) the cab length for longhaul cabs usually is around 2.3 m. Since the 2020s, new European legislation [25] offers new options for the maximum authorised dimensions in international European traffic. Vehicles which exceed the old length limit are permitted if they offer additional efficiency—especially aerodynamics is mentioned in the directive—and contribute to road safety. The loading length may not be increased, so the additional length might benefit the cab, a possible short hood or superstructures (tanks) behind the cab and mustn’t increase the cargo area. First cabs using this additional design freedom are offered [10]. 3.3.1.2 Exceptions There are exceptions to every rule. And this rule is no exception: Tractors and equipment for use in agriculture and forestry are permitted to be up to 3 m wide. Vehicles that do not conform to the dimensions above or which exceed the weight restrictions listed below can be operated as heavy-duty transporters with special authorization. This is necessary for larger and heavier loads.

3.3.2 Weight and Size Regulations in the US In order to protect roadways and bridges, heavy-duty vehicles are subject to weight limitations per unit length, as well as their length, width, height, and the types of trailers they may pull. US weight laws are referred to as bridge laws, in that they protect bridges and involve calculation of the weight on any one bridge (combination of axles) within a vehicle. The bridge formula was introduced in 1975 to reduce the risk of damage to highway bridges

3.3 Dimensions

29

by requiring more axles, or a longer wheelbase, to compensate for increased vehicle weight. The formula may require a lower gross vehicle weight, depending on the number and spacing of the axles in the combination vehicle. In order to comply, vehicles must limit overall weight and provide enough distance between axles to spread the weight across a large area of roadway. Compliance with the Federal Bridge Formula weight limits is determined by using the formula or table of Fig. 3.7. Beyond the limits of this formula, no single axle may support a gross load of more than 20,000 lb, no tandem more than 34,000 lb, and no vehicle (without a special permit) more than 80,000 lb. The vehicle with weights and axle dimensions shown in the Fig. 3.8 is used to illustrate a Federal Bridge Formula check. Before checking for compliance with the Federal Bridge Formula, a vehicle’s single-axle, tandem-axle, and gross weight should be checked. Here, the single axle (1) does not exceed 20,000 lb, tandems 2–3 and 4–5 do not exceed 34,000 lb each, and the gross weight does not exceed 80,000 lb. Therefore, these preliminary requirements are satisfied. Truck weight is regularly checked in the US. In the United States and Canada, on-road vehicles are limited to 2.6 m, or approximately 102 inches width, with certain items exempted from consideration (including mirrors). Aerodynamic features that extend less than 3 inches from the side of a vehicle are not counted. In other countries, the width limits are more extreme and the exempted items more limited. For example, in Australia, the width limit is 2.5 m and aerodynamic features count in the width measurement. Similarly, vehicles are limited in length. In the United States and Canada, straight trucks are limited to 40 ft, and trailers are generally limited to 53 ft (with limited exceptions). Tractors’ lengths are generally not regulated, only the trailers. Certain types of trailers may be used in certain states, but generally a 53 ft trailer is compliant. Each state has its own rules and certain heavy-haul types of trailers are permitted in some states but not others. These specifications are just a general rule of thumb and care should be exercised to ensure vehicles comply with the local requirements. Vehicles are limited generally to 13 ft six inches in height (approximately 4.12 m in SI units), except when granted with a special permits. Notwithstanding the height rules, what constrains the height of the vehicles many times is the height when piggy-backed for initial transportation. All of these regulations are enforced through roadside inspections. If a vehicle is found during a roadside inspection to be oversized or overweight for its size, then the vehicle inspector may ticket the driver or hold the vehicle, preventing further operation. Figure 3.2 illustrates the permissible outer dimensions in the United States.

30

3  Entire Vehicle

Fig. 3.7   Bridge Formula and table to determine weight limits in the US

3.3.3 Conventional and cab-over-engine tractors in Light of the Length Regulations The strict length restrictions on European trucks have led to the predominance of the “cab-over-engine” configuration. Cab-over-engine means that the cab is located over the engine. In other regions—notably in North America—cab-over-engine is rather a rarity.

3.3 Dimensions

31

Fig. 3.8   Illustration of a Federal Bridge Formula check for a tractor semitrailer

Fig. 3.9   Two concept vehicles: a the Mercedes-Benz Future Truck from 2014 and b the Freightliner Inspiration Truck from 2015. Concept vehicle a is a cab-over-engine vehicle in which the cab sits above the engine. Concept vehicle b is a cab-behind-engine vehicle such as are commonly used in North American long-distance haulage. (Photos: Daimler)

As stated above, tractors’ lengths are generally not regulated in North America, only the trailers. Hence conventional tractors (cab-behind-engine configuration) are widespread. In the cab-behind-engine configuration the engine is in front of the cab and covered by a hood. Figure 3.9 shows the difference between cab-over-engine and cab-behind-engine using the example of two concept vehicles. The conventional vehicle (cab-behind-engine) has a number of advantages: It is easy for the driver to get into the cab, and the engine is readily accessible. One has to just pop the hood, similar to a car. The installation position of the engine is also less constricted, which incidentally helps with cooling the engine. The complicated cab

32

3  Entire Vehicle

mounting (rotating at the front and detachable at the back) and the cab tilting mechanism of a cab-over-engine solution are not required. Naturally, the cab-behind-engine vehicle has a long wheelbase, and the driver is seated between the axles. This arrangement offers a good level of driving comfort and involves considerably less effort than with cab-overengine versions, in which the driver’s seat is positioned over the front axle. On the other hand, in light of restrictions governing the total length of the vehicle, the cab-over-engine configuration affords much more cargo space in a limited total length. Since this extra cargo space is crucial for the profitability of the operation, in Europe, Japan, China and other regions of the world with length restrictions the cab-over-engine variant is the dominant version seen on the roads.

3.4 Weights and Axle Loads Not only the dimensions but also the permissible weights and axle loads of a vehicle are governed by legally enforced restrictions. These are fixed by the legal authorities to increase road safety and to slow the rate of wear and damage to roads. The weight of a vehicle or trailer with its load is the gross vehicle weight (GVW) and the gross combination weight (GCW) is the weight of the vehicle AND the trailer fully loaded.

3.4.1 Permissible Gross Vehicle Weights and Gross Combination Weight In Europe and other countries, the permissible gross vehicle weight of a commercial vehicle depends on the number of axles. The European limits are shown in Table 3.1 below. The standard long-haul tractor-semitrailer-combination can have a gross combination weight of 40 t. For vehicles transporting sea container a maximum weight of 44 t is permitted. Country specific additional regulations might apply. In some Northern European countries truck trains with 60 t can be seen. In the US the maximum GCW of a standard longhaul tractor-semitrailer combination are the above mentioned 80,000 lbs, which equals 36.3 t. In China the gross combination weight of a tractor-semitrailer combination depends on the axle configuration of the tractor: with a 4 × 2 tractor a gross vehicle weight of 42 t is permitted, with a 6 ×2 tractor 46 t are permitted and with a 6 × 4 tractor one can have a total gross combination weight of 49 t.

3.4  Weights and Axle Loads

33

Table 3.1  Permissible gross vehicle weight of a motor vehicle, a trailer and vehicle combinations pursuant to 96/53/EC Vehicle

Permissible gross vehicle weight (t)

Motor vehicles with 2 axles

18

Motor vehicles with 3 axles

25

Motor vehicles with 3 axles with dual tires and air suspension

26

Motor vehicles with 4 axles (and more)

32

Trailers with more than 2 axles

24

Two-axle motor vehicle with two-axle trailer

36

Two-axle semitrailer tractor with two-axle semitrailer

36

Two-axle semitrailer tractor with two-axle semitrailer having dual tires and air suspension on the drive axle

38

Vehicle combination with more than four axles

40

Table 3.2  Permissible axle loads for Europe pursuant to 96/53/EC Axle

Maximum permissible axle load (t)

Non-driven single axle

10

Driven single axle

11.5

Motor vehicle, double axle with wheelbase