Vocational Vehicles and Applications (Commercial Vehicle Technology) 366260843X, 9783662608432

Table of contents :
Preface
Contents
1 Vocational Vehicles
2 Vocational Vehicle Preparation by the Vehicle Manufacturer
2.1 Payload-Sensitive Transport
2.2 Large-Volume Transports
2.3 Pickup and Delivery Haulage
2.4 Construction Sites and Off-road
2.5 Cold Weather and Winter Operations
2.5.1 Improving Starting Response
2.5.2 Traction Assistance
2.5.3 Other Options for Low-Temperature Operation
2.6 Fire Trucks
3 Bodies
3.1 Subframes
3.2 Integrating the Superstructure with the Vehicle
3.3 Electronic Integration of the Superstructure
3.4 Supplying Mechanical Energy Supply to the Superstructure
4 Trailers and Semitrailers
4.1 Various Truck Trailer Combinations or Hitched Combinations
4.1.1 The Tractor Semitrailer Combination
4.1.1.1 The Fifth Wheel Coupling
4.1.1.2 Landing Legs
4.1.2 Turntable Drawbar Trailer
4.1.2.1 The Trailer Hitch
4.1.3 Drawbar Combination with Center Axle Trailer
4.2 Electrical and Electronic Connection Between the Towing Vehicle and the Towed Unit
4.2.1 North America
4.2.2 Europe
4.3 Trailer and Semitrailer Chassis
4.3.1 Brake in the Trailer
4.3.2 The Suspension
4.3.3 Lift Axles for Semitrailers
4.3.4 Further Fittings for the Towed Unit
4.3.4.1 Separate Stowage Space
4.3.4.2 Shipping of a Semitrailer
4.3.4.3 Side Paneling/Aerodynamic Detachable Parts
4.3.4.4 Distance Calculation
4.3.4.5 Other Equipment
4.4 Loading and Unloading
4.4.1 Crane Function
4.5 Load Securing
4.6 Driver Assistance Systems in Trailers or Semitrailers
5 Equipment for Typical Truck Application Areas
5.1 Distribution Transport
5.2 Fresh Food Transports
5.3 Dump Truck
5.3.1 The Tractor Semitrailer Combination in Construction
5.4 The Tank/Bulk Sector
5.4.1 Transport of Liquids in Tankers
5.4.2 Bulk Transports
5.5 Transport by Sea Container
Comprehension Questions
Abbreviations and Symbols
References
Index

Citation preview

Commercial Vehicle Technology

Michael Hilgers Wilfried Achenbach

Vocational Vehicles and Applications

Commercial Vehicle Technology Series Editors Michael Hilgers, Weinstadt, Baden-Württemberg, Germany Wilfried Achenbach, HPCC2D-ENG, Daimler Trucks North America LLC, Portland, OR, USA

More information about this series at http://www.springer.com/series/16469

Michael Hilgers · Wilfried Achenbach

Vocational Vehicles and Applications

Michael Hilgers Daimler Truck Stuttgart, Germany

Wilfried Achenbach Daimler Truck Portland, OR, USA

Commercial Vehicle Technology ISBN 978-3-662-60843-2 ISBN 978-3-662-60844-9  (eBook) https://doi.org/10.1007/978-3-662-60844-9 © Springer-Verlag GmbH Germany, part of Springer Nature 2021 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. Planung/Lektorat: Markus Braun 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 derive just as much pleasure from trucks as I do, and for my wife, Simone Hilgers-Bach, who indulges us.

I have worked in the commercial vehicle industry for many years. Time and again I am asked, “So you work on the development of trucks?” Or words to that effect. “That’s a young boy’s dream!” Indeed it is! Inspired by this enthusiasm, I have tried to learn as much as I possibly could about the technology of trucks. In the process, I have discovered that one have not really grasped the subject matter until one can explain it convincingly. Or to put it more succinctly, “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. As a rule, the commercial vehicle is not ready for the road until it has received the body it needs for the task it is built to do. There are only quite a small number of largescale truck manufacturers, but many hundreds of companies which build bodies, trailers and tractor semitrailer combinations. So this volume cannot describe the enormous variety of specifications and solutions exhaustively. I believe I have found a good selection, that will provide a useful introduction for readers who are interested in learning about such things (students, technicians). In addition, I am convinced that this booklet will provide added value for technical specialists from related disciplines who would like see the bigger picture, and are looking for a compact and easy-to-understand summary of the subjects in question. At this point I would like to thank my superiors and numerous colleagues at the truck division of Daimler AG, who so readily gave me their support while I was working on this series of booklets. A very big thank you goes to Mr. Georg-Stefan Hagemann, who

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Preface

proofread the entire work. I would like to thank Springer Verlag for their friendly cooperation, which has led to this final result. I wish you much reading enjoyment. Weinstadt-Beutelsbach Stuttgart-Untertürkheim Aachen September 2019

Michael Hilgers

Contents

1 Vocational Vehicles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Vocational Vehicle Preparation by the Vehicle Manufacturer . . . . . . . . . . . . . 3 2.1 Payload-Sensitive Transport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Large-Volume Transports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 Pickup and Delivery Haulage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4 Construction Sites and Off-road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.5 Cold Weather and Winter Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5.1 Improving Starting Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.5.2 Traction Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.5.3 Other Options for Low-Temperature Operation . . . . . . . . . . . . . . . . 11 2.6 Fire Trucks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3 Bodies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.1 Subframes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2 Integrating the Superstructure with the Vehicle. . . . . . . . . . . . . . . . . . . . . . . 14 3.3 Electronic Integration of the Superstructure . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4 Supplying Mechanical Energy Supply to the Superstructure . . . . . . . . . . . . 17 4 Trailers and Semitrailers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.1 Various Truck Trailer Combinations or Hitched Combinations . . . . . . . . . . 19 4.1.1 The Tractor Semitrailer Combination . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1.2 Turntable Drawbar Trailer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.1.3 Drawbar Combination with Center Axle Trailer. . . . . . . . . . . . . . . . 24 4.2 Electrical and Electronic Connection Between the Towing Vehicle and the Towed Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2.1 North America. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2.2 Europe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.3 Trailer and Semitrailer Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.3.1 Brake in the Trailer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.3.2 The Suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ix

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4.3.3 Lift Axles for Semitrailers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.3.4 Further Fittings for the Towed Unit. . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.4 Loading and Unloading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.4.1 Crane Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.5 Load Securing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.6 Driver Assistance Systems in Trailers or Semitrailers. . . . . . . . . . . . . . . . . . 33 5 Equipment for Typical Truck Application Areas. . . . . . . . . . . . . . . . . . . . . . . . 35 5.1 Distribution Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5.2 Fresh Food Transports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.3 Dump Truck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 5.3.1 The Tractor Semitrailer Combination in Construction . . . . . . . . . . . 39 5.4 The Tank/Bulk Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 5.4.1 Transport of Liquids in Tankers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 5.4.2 Bulk Transports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.5 Transport by Sea Container. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Comprehension Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Abbreviations and Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

1

Vocational Vehicles

When the commercial vehicle leaves the plants of the big vehicle manufacturers, the commercial vehicle is often not yet in a condition to carry out its intended duties. At the assembly plant of the vehicle original equipment manufacturer (OEM), a chassis or tractor unit rolls off the production line, but it typically still needs a body or semitrailer (and possibly a trailer as well) to make the vehicle ready for its intended use. Bodies, trailers or semi-trailers are necessary to enable the vehicle to perform the tasks the customer has in mind for the vehicle. Specialist companies offer an enormously diverse range of bodies, trailers and semi-trailers. Figure 1.1 shows some  of the numerous vehicle variants which are equipped with trailer and body for specific customer applications. A  distinction may be made between the usage of  trucks primarily for  transportation of goods  and usages  in which the truck supports other services. The classic transportation task is moving goods from A to B. Work tasks for which vocational vehicles are used include street sweeping, refuse or garbage collection, concrete mixing, crane transportation, etc. In these cases, the vehicle’s primary function of the company operating the trucks is not carrying loads. Reference [13] includes a link to a website describing many special applications for commercial vehicles. These are listed in Fig. 1.2. Some body variants are used mainly on vehicle whereas others are encountered more often as trailer bodies in the semitrailer sector.

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9_1

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1  Vocational Vehicles

Fig. 1.1   A few examples of purpose-built variants: a tipper semi-trailer for building site work; b allwheel drive dumper; c long-haul tractor semi-tailer combination; d garbage truck e unimog for winter operations; f refrigerated body for distribution haulage. (Photos: Daimler AG)

Fig. 1.2   Some applications for which vocational vehicles are used

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Vocational Vehicle Preparation by the Vehicle Manufacturer

The vehicle operator (the buyer) wants to find a vehicle (truck or tractor unit, for example) that will perform the specific function they have in mind as economically as possible. To help, truck manufacturers offer vehicles that are specially prepared for use in certain industries, taking into account the particular industry requirements. These vehicles are then modified for their respective tasks by truck equipment manufactures (TEMs).

2.1 Payload-Sensitive Transport Some applications demand a vehicle that is capable of carrying particularly heavy loads (payload). For various transportation tasks, the vehicle is regularly loaded up to the legally permitted total vehicle weight – in the US, the limit is 80,000 lbs  (approx. 36.3 t); for example, in Germany the limit is 40 t, or 44 t for intermodal traffic. For these transportation tasks, it is advantageous from the fleet’s point of view to increase payload by reducing the truck’s  curb weight. The lighter the unladen vehicle is – together with its semitrailer or trailer – the heavier the load it is able to carry, which in turn increases the profitability of the transport task. Transport tasks in the bulk hauler segment are particularly payload-sensitive, and a lightweight vehicle is desired – see Sect. 5.4. There are many possible strategies for reducing a vehicle’s curb weight. Especially in vehicles with a relatively simple application  profile, such strategies may include, for example, installing smaller engines than are fitted in a standard tractor unit. Table 2.1 illustrates the weight differences between different engine classes that are offered for typical longhaul vehicles. For very weight-sensitive applications, special lightweight frames are also possible; the frame support members are thinner than the usual design. Of course, this also means that a lightweight vehicle built in this way cannot withstand the same load inputs as the © Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9_2

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2  Vocational Vehicle Preparation by the Vehicle Manufacturer

Table 2.1  Potential of smaller engines for reducing vehicle curb weight. Figures represent guidance values only Displacement

Engine weight

Output range

Torque range

7–8 l

Approx. 700 kg

Up to 360 hp

Up to 1500 Nm

Approx. 10.5 l

Approx. 950–1000 kg

Up to 450 hp

Up to 2100 Nm

12–13 l

Approx. 1050–1150 kg

Up to 500 hp

Up to 2500 Nm

corresponding standard configuration. Single-leaf springs on the front axle reduce weight, but also limit the vehicle’s robustness. Wide-base tires are lighter than the standard dual assembely tires on the drive axle. The absence of a spare tire is an inevitable consequence of wide-base tires anyway. A spare wheel for a tractor unit with standard tires weighs about 100 kg. Aluminum air tanks reduce the curb weight of a vehicle by 10 to 40 kg; lightweight metal wheels also make it lighter. Weight can be saved on the tanks by installing small tanks and also using aluminum or even plastic for the fuel and DEF (AdBlue) reservoirs. Vehicles that are specified to reduce weight are typically fitted with narrow cabs, which are only 2.30 m wide. And in the cab itself, ­weight-optimized windshields might be used (the window glass is thinner). Spartan cab equipment reduces the vehicle weight still further. This includes using thinner floor coverings in certain areas and reducing unnecessary cab furnishings. In this context even the passenger seat can be omitted to realize the weight-optimized vehicle. Smaller batteries with less capacity (e.g. 140 Ah instead of 170 Ah) lower the weight. If the thick battery cables are made from aluminum instead of the traditional copper, these too help to reduce weight with no loss of functionality. Removing the roof spoiler and side deflectors is another possible way to reduce weight; this of course must be weighed against the additional fuel consumption due to increased air drag.

2.2 Large-Volume Transports Besides tasks in which the vehicle is loaded to the limit of its payload capacity, the second obvious limit is the volume of the load area. When transporting light goods or loads which by their nature contain a lot of air or packaging, the fleet cannot fill the vehicle to its total weight limit because the load area is not big enough. In order to be able to transport as much as possible, volume-optimized tractor trailer combinations are offered. The vehicle manufacturer therefore makes vehicles with a low frame, called low-liners. They are fitted with low-section tires and feature an extra flat fifth wheel. Tractor semitrailer combinations can then be built with a coupling point height of 900 mm (approx. 35 in). With the right body or semitrailer a 3 m cargo space can be obtained in a 4 m high vehicle. In the automotive industry, a loading height of 3 m is a key target dimension for parts logistics, for example: in the automotive industry, bulk boxes (or pallet boxes) with

2.3  Pickup and Delivery Haulage

5

a height of 1 m are commonly used. With a loading height of 3 m, three of these boxes can be stacked on top of each others instead of just two. Still more loading volume can be made available in the semitrailer area if the lowbed, also known as lowboy, is offset downwards behind the fifth wheel to create more space for cargo – Fig. 2.1. With a lowbed frame, the vehicle can transport taller loads than is possible with the standard tractor semitrailer combination. When transporting ­high-standing cargoes, machinery and also automobiles (especially trucks!), the height limit is an important factor in many countries. The lowbed frame also has one more advantage for transporting vehicles or on-site heavy machinery in that the ramp for loading the vehicle onto the transporter is lower.

2.3 Pickup and Delivery Haulage Vehicles that are used mainly for delivering goods within a regional radius are called pickup and delivery vehicles (distribution vehicles), in contrast to long-distance haulage, which describes transportation of goods over longer distances. Conventional pickup and

Fig. 2.1   Schematic representation of a standard tractor semitrailer combination (top) and a semitrailer with a lowbed. In order to optimize the transport volume, lowbed trailers are often mounted on smaller tires

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2  Vocational Vehicle Preparation by the Vehicle Manufacturer

delivery profiles include delivering food to multiple retail stores, supplying heating oil to households and construction materials to construction sites. This does not usually require the driver to sleep in the vehicle. Smaller cabs with less consideration for functions such as living and sleeping are sufficient. Pickup and delivery applications impose a particular set of demands on the vehicle: Since the truck is driven in urban traffic for a greater proportion of the time, it is very important for the cab to provide good all-round visibility. The driver typically has to climb in and out of the cab several times a day, so a convenient access to the cab is desirable. Fewer steps and a staircase-like construction are helpful in this situation [4]. The truck equipment manufacturers also offer bodies and special equipment variants for this application – see Sect. 5.1.

2.4 Construction Sites and Off-road The most important design features for enabling a truck to operate on rough terrain and in harsh construction environments are those relating to the drive system and the chassis. Traction on slippery or soft surfaces is provided by multiple driven axles. A drivetrain with high drivetrain ratio enables very slow crawl speed and generates high torque at the wheels. This makes launching easier and enhances the vehicle’s gradeability. These vehicles are also often fitted with transmissions that include more gears and correspondingly smaller gear steps than long-haul trucks. An important requirement for vehicles working on uneven terrain is that they remain clear of the ground. So vehicles that are intended for off-road use typically have high ground clearance. In order to guarantee high ground clearance, bolt-on components such as tanks, the exhaust system, and so on, must not hang too low. In addition, sometimes offset axles (portal axles)  are used, so that as much space as possible is created underneath the axle housing. The gradients and inclines the vehicle can negotiate also factor into its off-road capability. Figure 2.2 explains the angles of approach/departure, the ramp breakover angle and the ground clearance between the axles. The ramp breakover angle ρ can be calculated approximately using the wheelbase r and the ground clearance h as follows:   2 · h ρ = 2 · arctan (2.1) r A short wheelbase leads to a large breakover angle. For driving through water, the vehicle’s fording, or wading, depth is also important; this specifies the maximum depth of puddles, etc. that the vehicle can drive through. Special equipment packages designed to increase the fording depth of vehicles are offered on vehicles destined for sale, mainly in the fire service, police, technical assistance and aid organization sectors. These include breathers that are routed upwards to prevent water penetration into the engine.

2.5  Cold Weather and Winter Operations

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Ramp breakover angle ρ

Ground clearance h

Approach angle

Departure angle Wheelbase r Fig. 2.2   Geometrical dimensions important for off-road and construction site activities

To configure a rugged vehicle, off-road trucks are built with steel suspension and drum brakes. And there are many other small details that help to adapt an off-road or construction vehicle for working more effectively in demanding environments. A coupling jaw, for example, can be mounted on the front of the vehicle for moving equipment and machinery around the construction site.  It can also be used to pull the vehicle itself out of the mud in case it might be stuck.  To protect the vehicle, deflectors are fitted underneath the radiator; these help to prevent the expensive radiator from being damaged by just a light knock against the ground, which in turn can lead to serious subsequent damage to the engine if unnoticed. In some vehicles, the lower level of the cab access steps is flexibly mounted. This helps to prevent the steps from being damaged by even slight contact with obstructions or the ground. Protective grilles in front of the headlamps protect them from stone chipping. Figure 2.3 shows what the grilles look like on a vehicle’s headlamp prepared for off-road use. Construction site vehicles often have a step on the side of the cab to enable the operator to look into the bed conveniently, and a corresponding grip to make it easier to climb the step. A vertical exhaust system with the exhaust opening at the top prevents the vehicle’s exhaust from raising too much dust on the construction site. The most important body (in terms of sheer numbers) in off-road and construction site applications is the dumper bed – see Sect. 5.3.

2.5 Cold Weather and Winter Operations To fit the vehicle for working productively in winter and/or in cold countries, there is a whole spectrum of technical solutions, special equipment packages and accessories designed especially for trucks. A powerful heater is a must. This can be combined with enhanced cab insulation and supplemented with auxiliary heating.

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Fig. 2.3   Details for construction site operations: protective grille for headlamps and flexible bottom cab access step. (Photo: Daimler AG)

2.5.1 Improving Starting Response In very cold temperatures, the engine doesn’t start as easily. The battery outputs less power, considerably more torque is required to turn the engine – and when the clutch is closed the transmission as well – because the engine oil and transmission oil become more viscous, and the ignition behavior in the combustion chamber is not as good. One useful feature that helps to toughen up the vehicle during low temperatures is the use of starter batteries with higher capacitance. Cold-optimized oils retain their flow capabilities for longer even at low temperatures, and so they reduce the amount of torque needed to start the engine. Unfortunately, these synthetic oils very often cost more as well. The flame start system serves to warm the air in the engine intake manifold. The intake manifold houses a dosing unit and a heater element. The metering unit drips diesel fuel onto the warm heater element. There, the diesel  reacts with the air, and releases heat. The air that reaches the combustion chamber is preheated, and the engine starts more easily, meaning engine wear is reduced. The engine cold-start capability is also improved and results in better emissions outputs. Electric preheating of the intake air serves the same purpose as the flame start system. In this case, however, heating is carried out electrically. A mesh arrangement with an electrical current passing through it is positioned in the air flow in the intake manifold and consumes about 2 kW of power for heating. The intake air flowing past this mesh is preheated when it reaches the combustion chamber.

2.5  Cold Weather and Winter Operations

9

The block heater is an externally supplied electric heater which heats the engine when the vehicle is parked. The block heater is connected to a 230 V (or 110 V) electrical socket by a cable. The heating element heats the engine coolant electrically like an immersion heater and the entire engine block as well. The engine oil flows more easily. This in turn makes the engine easier to start.

2.5.2 Traction Assistance The best traction assistance quite simply consists of additional driven axles – see [2]. These may be driven directly via propeller shafts, or they may be designed as an additional hydraulic axle. The following additional equipment items also serve to improve vehicle traction and are used in Nordic or Alpine countries, or in winter conditions. Traction assistance by increasing axle load  In vehicles with a non-driven rear axle, the load on this axle is relieved pneumatically, placing increased load on the drive axle to help with launch. The traction at the drive axle is increased for slippery roads or uneven surfaces. The load on the axle is usually increased for a short time only and is deactivated after a certain speed is reached so that the chassis components are not unduly stressed. Snow chains are recommended for wintry conditions. In some countries snow chains are a legal requirement for trucks using certain roads. There are snow chains that are only fitted on the outer tire of the twin set, as well as twin chains that fit over both tires. Twin chains are particularly necessary if the road or track is cambered. This is illustrated in Fig. 2.4. Snow chains that are only fitted on the outer tire of the twin set do not provide the best help on crowned roads. Fig. 2.4   Schematic illustration of the need for twin chains on difficult surfaces

Forest track

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2  Vocational Vehicle Preparation by the Vehicle Manufacturer

A relative of the snow chain is the automatic snow chain, or pop-out tire chain. With these, a rotating device projects chain segments in front of the tires. A round disc is forced (with compressed air) against the inner side of the driving wheel by a swivel arm. This causes the disc to rotate in much the same way as a dynamo on a bicycle. Under the effect of centrifugal force, chain links attached to the disc are thrown in front of the wheel, and the tire rolling over them gains traction. The rotating speed of the automatic snow chain is automatically synchronized with the speed of the wheel. When the vehicle is reversed, the automatic snow chain changes its rotating direction as well. Figure 2.5 shows the operating principle of the automatic snow chain. The automatic snow chain can be activated while driving, so it is ready for immediate use, and can be deactivated just as quickly. This is its major advantage over the fitted snow chain, which must be fitted and removed; the driver has to stop and get out of the vehicle and grapple with the chains while exposed to the elements. On the other hand, the automatic snow chain only improves traction when both the wheel and the chain are turning. When the wheel is at a standstill, this chain does not work. It is also less effective than the snow chain during a braking procedure or when the wheels are slowing or even locked. And the automatic snow chain reduces ground clearance of the vehicle. If snow chains are mandatory (Fig. 2.6), automatic snow chains are not sufficient. In some countries where snow and ice cover remains on the ground for longer periods, studded snow tires are also used. These are winter tires with embedded metal studs that protrude radially outwards. These afford very good traction on packed snow and icy

a

b

atio

Rot no e

f tir

Direction of rotation of the rotating disc

Rotating disc

Chains

Fig. 2.5   Operating principle of the automatic snow chain. a Diagrammatic representation. The chain elements are shown as lines here, in reality they are short lengths of connected chain links. b Automatic snow chain in operation. (Photo: M. Hilgers)

2.6  Fire Trucks

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Fig. 2.6   Snow chains mandatory – Sign 268, see [5]

roads. But when the roadway is not covered with snow or ice, they interfere with normal driving and damage the pavement. Studded tires are used in Scandinavia and are allowed in a number of states in the U.S. In some other U.S. states and in most European countries like Germany, for example, their use is prohibited.

2.5.3 Other Options for Low-Temperature Operation For cab over engine configurations, the oil in the cab hydraulic tilting mechanism is affected in the same way as the engine oil by low temperatures: it becomes viscous. Accordingly, special oil for the hydraulic tilting mechanism is available for cold conditions. A suitable fuel variant called winter diesel and a higher antifreeze content in the coolant are used during low temperatures. For construction site vehicles, heated dump beds are offered. These prevent the bulk material from freezing to the sides and bottom of the bed or slow the cooling process for warm bulk materials such as bitumen. They are heated by passing some of the exhaust gas through cavities in the dump bed. The vehicle manufacturer offers a corresponding connection to the exhaust system, and the dump bed manufacturer is responsible for ensuring that the gases are properly routed through the dump bed and discharged.

2.6 Fire Trucks The defining technical bodies that transform a vehicle into a fire truck are put on by the body manufacturer. To support it, the vehicle manufacturers build chassis that are prepared to receive the fire service body. It is particularly important that as few parts as possible take up space on the outside of the frame, because this space is needed for stowing

12

2  Vocational Vehicle Preparation by the Vehicle Manufacturer

Fig. 2.7   Fire trucks based on various Mercedes vehicles: a Group fire-fighting vehicle mounted on an Atego; b Telescopic mast on an Antos; c Turntable ladder on an Econic; d Fire service Unimog for use on roads and railroad tracks (road-rail vehicle). (Photos: Daimler AG)

as much fire-fighting equipment as possible. Europe-wide standards do exist for vehicles that are destined for use by fire services, but there is still an enormous variety in the bodies that are built onto the trucks. Figure 2.7 shows some examples. Many fire departments have specific requirements which the body manufacturers must meet. There is an abundance of reference literature on fire trucks.

3

Bodies

Bodies are produced by truck equipment manufacturers (TEMs) with the necessary combination of specific industry knowledge and custom technology.1 Figure 3.1 shows nine of the countless variants created by adding a body to the chassis from the OEMs. The number of TEMs (body builder) and specialized bodies is legion. To ensure that the bodies are perfectly matched to the motor vehicle, there are detailed guidelines for the TEMs describing how the bodies must be adapted to the base structure [13, 18, 19]. The vehicle must also satisfy the relevant requirements and regulations after it has been completed or converted by the TEM. Selecting the correct base vehicle for the superstructure Some basic vehicles from the OEM’s range are more suitable for a given body than others. Some vehicle variants are also impossible to combine with certain bodies. Important features that should be considered when selecting the base vehicle are, for example: • • • • • •

geometric features such as wheelbase and overhang, clean back of cab, engine output/engine torque, transmission set-up and axle ratio, power take-offs, and permissible gross vehicle weight and permissible axle loads. The tire load capacity must also be borne in mind.

1Simple

and often specially ordered bodies like swap-body systems, dump trucks or box bodies are often assembled on the OEM’s production lines. But this does not alter the fact that it is the TEM that takes care of the technical design of the body.

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9_3

13

14

3 Bodies

Fig. 3.1   Purpose-specific bodies on base vehicles: a Concrete mixer; b Catering vehicle for the airport apron; c Logging truck; d Street sweeper; e Refrigerated body; f Snow plow; g Skip loader; h Tanker truck; i Dump truck with loading crane. (Photos: a; b; d; e; and i: Daimler – c; f; g: MAN – h: Schwarzmüller)

3.1 Subframes The body is mounted on the frame of the base vehicle (see also [2]). For some bodies, a second frame – the subframe – is attached to the actual vehicle frame first. This usually consists of longitudinal members in the form of U-beams, less often box sections connected by crossmembers. The subframe is mounted on the actual vehicle frame. The function of the subframe is to increase the overall rigidity of the vehicle and the body. Instead of the subframe, the vehicle frame can also be strengthened with reinforcements. Reinforcements of this kind are, for example, U-beams, which are inserted in the vehicle frame in internal reinforcements and bolted in position; or cross struts, which strengthen the vehicle frame. If the bodies are self-supporting, subframes may not be needed. Box bodies can be designed as self-supporting elements.

3.2 Integrating the Superstructure with the Vehicle In some cases, the body can fundamentally change the nature of the vehicle. The TEM must therefore ensure that certain properties of the vehicle are still intact after the body has been added. Most important of these is of course safety, but vehicle noise (inside

3.3  Electronic Integration of the Superstructure

15

and outside), service life of the components or repairability  of the entire vehicle are also aspects the TEM must never neglect. The manufacturers of the base vehicle usually give precise specifications in their guidelines for the TEM which the TEM must also comply with. The body shifts the vehicle’s center of gravity. If the center of gravity is shifted significantly upwards (high load), stabilizers must be provided. For vehicles with an electronic stability program (ESP – see [3]) the option exists to adapt the parameters of the ESP to high load [13]. Sufficient clearance must be provided between the body and the cab. This clearance must be large enough to allow the cab to be tilted; and the body and the cab must not collide when the vehicle twists on rough terrain (torsion), for example.

3.3 Electronic Integration of the Superstructure The body must usually be integrated electrically/electronically with the chassis built by the vehicle manufacturer. A simple electrical integration consists in supplying the power to the body from the vehicle’s on-board electrical system for simple uses (lamps, side marker lights for bodies over 6 m long, or similar). The vehicle manufacturer ­suggests

2b

8 3a

7

6

+ -

1 1 2a 2b 2c 2d 3a 3b 4 5 6 7 8

2a = = = = = = = = = = = =

3b

4

Direct engine output front only fire-fighting vehicle series) Indirect engine output front, crankshaft belt pulley Indirect engine output front, generator drive Indirect engine output front, for hydraulic pump Indirect engine output front, water pump belt pulley DAF engine power take-off Flywheel engine power take-off (ZF) Transmission output Transfer case power take-off Connection for electrical system Connection for compressed air system Connection for engine cooling system

5

G000293

Fig. 3.2   Various options for splitting energy off from the base vehicle to supply a vehicle body. (Image reproduced from [18])

16

3 Bodies

defined branching points where the TEMs can draw the electrical current off for the body. The superstructure might add further load to the vehicle’s electrical system. Depending on how much electrical power is needed, it is advisable to equip the vehicle with high-performance batteries and a more powerful  alternator  at the factory. For vehicle bodies that are intended for transporting hazardous materials, the on-board electrical system on the base vehicle must be equipped with an emergency OFF switch. In more complex electronic integration arrangements, the vehicle and the body exchange messages. For this, the base vehicle has an interface the TEM can use to

Superstructure type/Energy supply matrix Application Air-conditioning system Loading crane Concrete mixer Concrete pump Bulk material compressor Skip unloading system Generator (alternator) High-pressure pump Elevating work platform Household refuse compactor Dump body (Frozen) refrigerated transport Vacuum sewer cleaning body Cargo liftgate Winch Compressed air consumers Body heater Tank body (for milk collection transport etc.) Fire engine/truck (fire-fighting body) 1 2a 2b 2c 2d 3a 3b 4 5 6 7 8

1

Energy suppliers 2a 2b 2c 2d ¦ ¦

3a

3b

4

5

6 ¦

7

8

¦ ¦ ¦

¦

¦ ¦

¦

¦

¦

¦

¦ ¦

¦ ¦

¦

¦

¦

¦

¦ ¦

¦

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦

¦

¦

¦ ¦ ¦

¦

¦ ¦

¦ ¦ ¦

¦

¦

= Direct engine output front (only fire-fighting vehicle series) = Indirect engine output front, crankshaft belt pulley = Indirect engine output front, generator drive = Indirect engine output front, for hydraulic pump = Indirect engine output front, water pump belt pulley = DAF engine power take-off = Flywheel engine power take-off (ZF) = Transmission output = Transfer case power take-off = Connection for electrical system = Connection for compressed air system = Connection for engine cooling system

Fig. 3.3   Truck manufacturer’s recommended assignment: Which energy sources/PTO from the motor vehicle are suitable for which application? The energy suppliers correspond to the various options from Fig. 3.2. (Image reproduced from [18])

3.4  Supplying Mechanical Energy Supply to the Superstructure

17

c­ onnect the body to the vehicle’s electronic system – see [3]. This enables the superstructure (body) to receive information from the vehicle, such as vehicle speed, gear selected, engine speed, or the status of the parking brake. In the other direction, the superstructure can send requests to the vehicle via the same interface. The request may be to increase engine speed, for example, When a concrete pump switches to delivery mode, it requests a faster engine speed to ensure that sufficient mechanical output is available at the power take-off.

3.4 Supplying Mechanical Energy Supply to the Superstructure A truck body often needs a source of driving power. Concrete mixer drums must rotate, loading cranes must be moved, street sweeping machines must be operated, among other possibilities. Figure 3.2 shows what branching options there are for meeting the energy requirements using the example of a specific vehicle manufacturer. Figure 3.3 shows the same truck manufacturer’s recommendation as to which power take-offs should be used as drive units for specific bodies and functionalities. Sometimes it is necessary for a trailer not only to receive power from the tractor unit but also for the trailer or semitrailer to have its own power source. Most notably, refrigerated semitrailers are equipped with an independent, diesel-powered energy supply (Sect. 5.2). This ensures that the cargo can still be cooled when the semitrailer is not coupled to the tractor vehicle.

4

Trailers and Semitrailers

Trailers are unpowered vehicles coupled to and towed by a powered vehicle. They are also called towed units. A distinction is made between trailers and semitrailers. The tractor unit and the semitrailer combined are characterized in that a substantial part of the weight of the semitrailer and its cargo is supported by and rests on the tractor unit.

4.1 Various Truck Trailer Combinations or Hitched Combinations Unpowered towed vehicles (i.e. trailers and semitrailers) must be securely coupled to the towing vehicle (tractor unit) by mechanical means. The electrical connection, which is just as important, will be discussed in Sect. 4.2. There are a number of different concepts for creating coupled combinations with a towing vehicle and a trailer. Probably the three most important combinations are the tractor semitrailer combination (Fig. 4.1), vehicle combinations  with  turntable drawbar trailer (see Fig. 4.3) and tractor combinations with center axle trailers (Fig. 4.6). The last two combinations are also called tractor/trailer combinations as opposed to the tractor semitrailer combination, which according to this definition is not a tractor trailer combination. The various mechanical coupling options must transmit forces from the driven tractor unit to the trailer. At the same time, the tractor unit and the trailer must be able to move relative to each other.

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9_4

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4  Trailers and Semitrailers

4m

16,50 m

Fig. 4.1   Tractor semitrailer combination. This vehicle combination is the most commonly used configuration on long-hauls

4.1.1 The Tractor Semitrailer Combination With the tractor semitrailer combination, the trailer is supported by fifth wheel coupling of the towing vehicle allowing it to pivot. This means that there is exactly one pivot point for the entire rig. In order to be able to combine different trailers and towing vehicles, the dimensions of the clearances between the towing vehicle and the trailer are defined in a standard [8]. There are height-adjustable fifth wheels for accommodating trailers with different hitching heights, and fifth wheels which are movable in the longitudinal axis of the tractor unit (x-direction) to change the offset between the rear axle and the fifth wheel kingpin, thereby adjusting the axle load distribution of the tractor. The load in the five-axle tractor semitrailer combination must be spread very carefully to ensure compliance with permissible axle loads [1].

4.1.1.1 The Fifth Wheel Coupling The fifth wheel coupling provides the mechanical connection between the tractor and the semitrailer. It supports a portion of the weight of the semitrailer and transfers this portion to the axles of the tractor, particularly the rear axles. Brackets are mounted on the sides of the tractor semitrailer combination frame where the fifth wheel is then bolted. The key element of the fifth wheel is the coupling plate, on which the semitrailer is supported. The coupling plate has an elongated opening, the open side of which faces the rear of the vehicle, and in which the kingpin of  the trailer is inserted. The kingpin is locked in place by a locking mechanism to ensure that it does not slip out while the vehicle is moving. The kingpin also has a groove running round its circumference so that the semitrailer cannot lift away from the coupling plate. The shape of the kingpin is standardized, so a towing vehicle can be combined with various semitrailers. Two sizes are common: kingpins for standard applications have a diameter of two inches, slightly more than 50 mm, [7] and kingpins for heavy load applications have a diameter of 3.5 inches, which is equal to a little less than 90 mm [9]. During cornering, the semitrailer pivots on the coupling plate. The pivot point is the kingpin. The coupling plate is greased or has a special low-friction surface so that

4.1  Various Truck Trailer Combinations or Hitched Combinations

21

Fig. 4.2   Basic structure of a fifth wheel. (Image by company Jost [15])

pivoting movement is not hindered. The fifth wheel serves as the point of articulation between the tractor and the semitrailer. The coupling plate is  tiltable about the transverse axis (axis in the y-direction), so that the tractor vehicle and the semitrailer can be at different tilt angles when they are driving onto a ramp. The basic construction of a fifth wheel is shown in Fig. 4.2.

4.1.1.2 Landing Legs The semitrailer is equipped with support legs or casters, the so-called landing gear, so that it can be uncoupled and parked. These legs support the front part of the semitrailer when it is not coupled to the tractor. When uncoupled, the weight of the semitrailer bears on the support legs and the semitrailer chassis. The landing gear is located closer to the rear axle than the kingpin. Consequently, the load that the landing gear supports is greater than the static load that is transferred to the fifth wheel as fifth wheel load. There are landing gear systems with different levels of sophistication. One simple system consists of detachable supports which are placed under the semitrailer before it is uncoupled. This system is inexpensive and lightweight, and most useful when the vehicle combination is very rarely separated. With the retractable leg support, the support legs are accommodated in a tube and are held in the raised position by stop pins when the vehicle is moving. When the pins are released, the support legs drop down and are secured in the lowered position by the pins again. The different heights at which the uncoupled semitrailer can be parked depend on the distance between the holes for the pins. The most convenient solution is offered by the telescopic landing gear with crank. The mechanical jack support is raised and lowered with the aid of a hand crank. There is a motorized version of the landing gear, in which the work is luckily done by a motor.

22

4  Trailers and Semitrailers

The jack support enables the height at which the semitrailer is parked to be adjusted continuously. The landing gear can also be used to adjust the height of the semitrailer after it is parked. This is helpful if a parked trailer is to be coupled to a different tractor on which the fifth wheel is at a different height. The supports are raised manually or by motor after the trailer is hitched to prevent them from scraping or catching on the ground while the vehicle is moving.

4.1.2  Turntable Drawbar  Trailer With the turntable drawbar  trailer, the front axle of the (at least two-axle) trailer is attached rotatably underneath the trailer. The A-frame tow bar or rigid drawbar is attached to the turntable. The tow bar connects the trailer to the tractor. Figure 4.4 shows various tow bar types. When cornering, the turntable  rotates (together with the rigid front axle of the trailer) beneath the trailer. The tractor trailer combination has two pivot points: at the first, the towing eye of the  drawbar  swivels in the coupling jaw, at the second, the turntable  turns. Drawbar combinations with turntables  are forgiving in corners during forward travel. The trailer hardly cuts the corner at all. But reversing is more difficult than with tractor semitrailer combinations or center axle trailers. A typical drawbar combination with turntable  trailer is illustrated in Fig. 4.3.

4.1.2.1 The Trailer Hitch A trailer hitch must be present on the vehicle for coupling the A-frame tow bar. The rear area of the vehicle (rear crossmember) must be strong enough to support the load when the vehicle is used with a trailer hitch in a tractor trailer combination. Trailer hitches are available in a wide variety of models [17]. The standard trailer hitch is the jaw-type coupling for towing  eyes. Figure 4.5 shows one example of the countless variants. There are variants with different sized coupling jaws and for different sized towing eyes. For

Maximum permissible length of the trailer 12 m 4m

Turntable trailer

System length 16.40 m Maximum permissible length of the motor vehicle 12 m

18.75 m

Fig. 4.3   Drawbar combination vehicle with turntable trailer

4.1  Various Truck Trailer Combinations or Hitched Combinations

A-frame tow bar

23

A-frame tow bar with angled towing eye and center pipe Towing lug angle

L d H B HL h

Offset A-frame tow bar

A-frame tow bar with swiveling eye

= Length = Bearing eye diameter = Bearing eye width = Span = Height offset = Throw

Length-adjustable A frame tow bar

Fig. 4.4   Various configurations of the A-frame tow bar for turntable  trailers. Image is based on a product brochure published by BPW [16]. The swiveling eye (bottom middle picture) has two different eye diameters, so the A-frame tow bar can be attached to couplings with different pin diameters

Fig. 4.5   Example of a trailer hitch. There are many different kinds available on the market. (Photo: Company Jost Rockinger)

24

4  Trailers and Semitrailers 0.75 m

e.g. 8.15 m

Hinged load platform for through-loading trailer

e.g. 7.50 m

Central axle trailer

System length 16.40 m

18.75 m

Fig. 4.6   Drawbar combination with center axle trailer. With this configuration it is possible to transport very large volumes. A folding bridge between the trailer and the motor vehicle makes it possible to load the entire combination through the rear

off-road applications, versions exist with a vertical articulation which allows an additional rotation about the vehicle’s transverse axis (Y-axis). There are also other coupling systems besides the jaw coupling for towing eyes, for example, hitch balls (as used in the passenger car sector) and pintle hook hitches.

4.1.3 Drawbar Combination with Center Axle Trailer The center axle trailer is a trailer with an axle group (one to maximum three axles) which are arranged centrally under the trailer. Connection to the towing vehicle is with a rigid drawbar. The center axle trailer is not supported (or only slightly) on the towing vehicle. With the arrangement of the axles below the trailer, the towed trailer turns with and follows the towing vehicle. The pivot point of the tractor unit is where the trailer drawbar is attached. To improve the stability of the tractor trailer combination with a center axle trailer, the center axle trailer is typically coupled deep below the motor vehicle (close to the rear axle of the vehicle). Motor vehicles with a center axle trailer are designed to provide a very large transport volume within the maximum possible dimensions of a drawbar combination (18.75 m overall length in Europe). With center axle trailers, the distance between the towing vehicle and the trailer can be kept small, so the total loading length is large. These combinations are also configured as through-loading trailers. The front wall of the trailer must be opened, a loading platform connects the trailer to the motor vehicle so that the total combination length can be loaded and unloaded from the rear. A disadvantage of the center axle trailer is that it must be loaded evenly, and it may be necessary to brace the front and rear of the trailer while it is being loaded, as there may otherwise be a risk that it will tip about the center axle(s).

4.2  Electrical and Electronic Connection …

25

4.2 Electrical and Electronic Connection Between the Towing Vehicle and the Towed Unit 4.2.1 North America In North America, the electrical connection between a semitrailer or trailer and the tractor unit is provided by an electric cable that has a seven-pin line connector. The ­seven-pin plug supplies electrical power for all lamps including markerlamps, tail lamps, turn signals and brake lights. It also supplies power to the trailer ABS unit. SAE also defines in the Standard J2497 a power line communication protocol to enable a trailer ABS lamp to be illuminated in the dash when a trailer ABS fault occurs.

4.2.2 Europe In Europe, the electrical connection between a semitrailer or trailer and the tractor trailer is provided by two electric cables. Modern vehicles have a seven-pin line and a 15-pin connector. Other, earlier connection configurations are also possible – two seven-pin plugs, for example. The electrical connection between the tractor unit and the trailer is defined in several standards – see [10] for the seven-pin plug and [11] for the 15-pin plug. [12] and the other standards listed there describe the exchange of information between the motor vehicle and the trailer. The seven-pin plug serves the brake network and the exchange of information for chassis functions. It includes the supply of power for the trailer electronics and the electrically actuated solenoid valves as well as a cable pair for CAN communication The fifteen-pin plug controls the trailer’s lighting system. It also contains control lines for a trailer lift axle if one is fitted and for centering a steering axle if the trailer is equipped with one. A CAN bus network enables the exchange of further information between the trailer or semitrailer and the tractor unit. This information is explained in [12] Part 3. Depending on how the trailer or semitrailer is equipped, the following is a selection of the data that can be transmitted: Information from the reverse warning device on the trailer, load compartment temperature, status of the theft alert system, monitoring of the trailer lighting system and more. Information about the towing vehicle can also be sent to the tractor unit. This may include, for example, the gear selected, the accelerator pedal position, travel speed, engine speed, or engine oil temperature. In order to prevent the trailer or semitrailer from being connected incorrectly to the towing vehicle, plugs and sockets are assigned as follows: In the tractor semitrailer combination, the cable is connected to the towing vehicle with a plug. The connecting sockets are on the trailer. In drawbar combinations, this assignment is reversed: the coiled cable and plug is fixed permanently on the trailer and the towing machine has the sockets.

26

4  Trailers and Semitrailers

Fig. 4.7   Air-sprung trailer axle with disc brake. (Photo: Daimler AG)

4.3 Trailer and Semitrailer Chassis 4.3.1 Brake in the Trailer The trailer and the semitrailer have their own wheel brakes. The brake system for the trailer or semitrailer is connected to the towing vehicle’s brake system via two pneumatic brake lines (and the electrical lines). The trailer brake valve is located in the trailer and communicates the braking action from the motor vehicle to the trailer brake system. It also brakes the trailer or semitrailer automatically if the brake hoses connecting the towing vehicle to the towed unit become detached. The difference in axle loads when braking force is applied is also handled in the trailer. Load-dependent braking force is spread evenly between the towing vehicle and the trailer. In (old) trailers in which load-dependent distribution of braking force is not adjusted automatically by the brake system, the brake pressure for the trailer brake can be reduced manually with a brake force regulator according to the loading level of the trailer.

4.3.2 The Suspension Trailers and semitrailers are offered with steel suspension and air suspension. Figure 4.7 shows a trailer axle with a disc brake and air suspension. Like the brake, the air suspension is supplied with the compressed air it needs by the tractor unit.

4.3  Trailer and Semitrailer Chassis

27

4.3.3 Lift Axles for Semitrailers In order to reduce the turning radius of the tractor semitrailer combination, the air suspension in the trailers is available with a function that raises the trailer’s hindmost axle when cornering sharply. The tractor semitrailer combination’s turning circle becomes smaller. The trailer electronics detect a cornering maneuver on the basis of the difference between trailer wheel speeds. Solenoid valves adjust the amount of air contained in the air bellows so that the last trailer axle is relieved or raised. Lift axles on the front position of the triple axle of a semitrailer are also common. If the first of the three axles is raised, the load on the fifth wheel increases. This can be done intentionally to improve traction and driving stability of the towing vehicle if the trailer is only lightly loaded or unloaded. There are also some trailers with three-axle units in which the first and third axles can be raised. When empty, the trailer runs on just one axle with reduced friction.

4.3.4 Further Fittings for the Towed Unit The transportation industry is highly competitive and extremely cost-conscious. Therefore, basic tractor units only offer standard features and functionalities. As a rule, (a wide range of) equipment extras are available to enhance the bare body. Many of these are task-specific – more about this later – Chap. 5. And there are also equipment packages for motor vehicles with superstructure, trailer and semitrailer, which are not directed at a specific sector.

4.3.4.1 Separate Stowage Space Besides the actual load area in the trailer or semitrailer, it often benefits efficient operation of the combination to have additional storage spaces for accessories. These may include pallet boxes, which are offered in various sizes, and spaces for stanchions fastened below the cargo area. Boxes for additional load-securing equipment and toolkits fitted under the cargo area by the manufacturer are also available. Storage boxes under the cargo area that can be reached through a flap in the vehicle floor can also be ordered. The advantage of these compartments is that they are easily accessible and protected from the elements under a tarpaulin or in the box. The disadvantage is that they are no longer accessible when the cargo area is loaded. Semitrailer manufacturers offer water barrels fitted on the trailer at the factory so that the driver always has fresh water available for washing his hands, etc.

28

4  Trailers and Semitrailers

4.3.4.2 Shipping of a Semitrailer Semitrailers are not only transported as towed units behind a tractor unit; they can also be moved by rail. For unaccompanied1 rail transportation, the semitrailers are lifted with special lifting gear (portal cranes or reach stackers) and set down on the railcar. For intermodal transport via railways, the trailer is fitted with grappler arm lifting areas to which the lifting harness is attached for lifting. When the trailer is air-sprung, the air suspension must be designed so that it will not be damaged by sudden rebounds and during lifting (axle hangs below the chassis). For loading onto ferries, special extra tie-down points are offered so that the trailer is securely lashed even in rough seas. 4.3.4.3 Side Paneling/Aerodynamic Detachable Parts Some semitrailers and trailers have side underrun protection systems. Those are mandatory in Europe, for example, but optional in the U.S. Side rails beneath the cargo area can serve as a side underrun protection system. Flat side paneling is visually more appealing and can be used as advertising space. The side paneling can be actively optimized to improve the aerodynamic characteristics of the trailer or semitrailer, and thus also of the vehicle combination as a whole. The photo on the left in Fig. 4.8 shows aerodynamically-optimized side paneling on a trailer.

Fig. 4.8   a Aerodynamic side paneling on a trailer. For easier access to the trailer jacks, the front part of the side paneling can be folded out. b Aerodynamic end wings on the trailer. (Photos: Hilgers)

1“unaccompanied”

in this case means that a tractor unit is not coupled in front of the trailer.

4.3  Trailer and Semitrailer Chassis

29

A part of the side paneling here is designed to fold back to provide access to the jack support/landing gear. The photo on the right of Fig. 4.8 shows a rear wing system for the rear of the trailer or motor vehicle (solo vehicle). The rear wings are angled inwards to reduce the (aerodynamically adverse) low pressure region behind the vehicle. This helps to reduce aerodynamic drag. These add-on parts are often called a trailer tail. The rear wing system must be constructed such that the rear doors can still be opened and closed without difficulty for loading and unloading. It must also be sturdy enough to withstand the harsh conditions of commercial vehicle operations (inclement weather, snow, loading activities etc.). Spoilers are also offered to improve aerodynamic performance and are mounted on the top rear edge of the trailer with the claim that they reduce aerodynamic drag.

4.3.4.4 Distance Calculation In order to measure the mileage traveled by a trailer or semitrailer devices called hubodometers2 are used. The hubodometer is located on the hub of a (non-liftable) axle and counts the revolutions per axle. Hubodometers with mechanical counters and electronic hub odometers are offered for sale. The hubodometer can be valuabe to fleet owners who want to keep an eye on the mileage of their vehicles. Companies that charge for rented equipment according to mileage also need tamper-proof hubodometers. 4.3.4.5 Other Equipment Many other items of equipment are offered for the truck and trailer purchaser to choose or upgrade to personalize his or her vehicle to their own needs. LED tail lamps help to lower maintenance costs, because LEDs have a significantly longer service life than conventional lamps. Work lamps on the motor vehicle and/or on the towed unit make loading and unloading easier, and are helpful when looking after the vehicle in the dark. Vehicles are driven with or without a spare wheel at the operator’s discretion and depending on the task. The spare wheel must be secured firmly to the vehicle. For handling the spare wheel, there are winches to lower the spare wheel or lift it again. For certain cargoes, it is mandatory to carry fire extinguishers in the vehicle. In international haulage, it may be required to fit the load area with a secure customs seal. Rubber buffers on the rear protect the vehicle when reversing to a loading bay.

2The

English word odometer is derived from Greek and means route measuring device.

30

4  Trailers and Semitrailers

4.4 Loading and Unloading Bodies, semitrailers and trailers are usually designed with rear doors that open when the vehicle docks in a loading bay. These are often hinged rear-end doors. They swing backwards and sideways to open. When space is tight, there are also roll-up gates at the rear that slide upwards like roller blinds. There are vehicle and trailer configurations in which it is permitted to drive with a forklift into the cargo space: a (relatively small) forklift truck can be driven through the rear into the load area to help with loading or unloading. In other situations, the load is not removed from the rear but is placed in or removed from the cargo area from the side using a forklift truck, for example. For these scenarios, some trailers and semitrailers are available in which the rear-end door has been replaced with a lighter, cheaper tarpaulin. Trailers which are often loaded from the side are ordered with tarpaulin side coverings. These can be opened easily by sliding them aside like curtains, hence trailers of this kind are called curtainsiders or tautliners. Lift systems for the roof have also been developed to facilitate loading and unloading from the side with a forklift truck. The semitrailer roof is raised hydraulically, so that the forklift truck can remove the cargo from the side more easily. An electric pump is installed in the lower region of the semitrailer to supply the hydraulic power for raising the pop-up roof. There are skylight roofs to make it easier to load, unload, and work in the cargo area. These are translucent roofs that allow daytime light into the load area. With a live floor or sliding floor system, the floor of the trailer is divided into many (long) longitudinal beams that can move short distances (20–30 cm) back and forth independently of the other beams. If the beams are all moved at the same time, the cargo migrates with them. Then the beams are individually moved back3 in the opposite direction one after the other until all of the beams are in their original positions again. Provided it is resting on enough beams, the cargo does not move with individual beams because the friction that traps them on the beams, which are not moving, is more powerful than the traction of the one beam which is moving. The moving beams slide underneath the cargo. Then the process starts again. The longitudinal beams are moved hydraulically and the tractor unit must be equipped with a hydraulic unit. The direction of movement is reversible, so the live floor technology can be used for both loading and unloading. Sophisticated trailers with adjustable intermediate bottoms make it possible to load the trailer with packaged items on two levels.

3or

in small groups.

4.5  Load Securing

31

4.4.1 Crane Function Loading cranes on the vehicle can be used to lift heavy goods such as construction materials or machinery (or parts of) onto the cargo area or unload them at the receiving destination without any additional help. Loading cranes are already very widely used in construction site supply traffic or on logging trucks. They can be mounted either directly behind the driver’s cab at the front of the cargo area or at the tail end of the vehicle. The typical loading crane folds up, so in the folded position it uses the entire width of the vehicle but only occupies a small lengthwise space. Vehicles with a loading crane also have support legs to ensure that the vehicle will remain stable while loading and unloading activities are carried out. Trucks with a loading crane have a cargo area, and still enough payload and space to transport goods. In addition, there is the mobile crane that is mounted on a truck chassis or a special crane chassis and does not leave any room for cargo. The cargo that actually needs to be transported and lifted is loaded on another vehicle. The mobile crane can lift much heavier loads and has a larger boom range than the loading crane.

4.5 Load Securing In order to be able to transport the cargo safely on or in the cargo area, it must be secured. There are many ways and means to secure loads. Many of these are optimized specifically for certain loads or load carriers. Some generally practical features and equipment for the cargo space/cargo area are described in the following section. An anti-slip floor increases the friction between the cargo and the floor. Consequently, the forces needed to secure the cargo against slipping are lower. The cargo area has tie-down eyes on the sides of the outer frame or in perforated rails in the floor for lashing the cargo. Perforated rail systems are also available with fitting wedges or eye bolts, which can be placed anywhere on the cargo area. Upright support posts in the cargo area are called stanchions. To secure the cargo, removable stanchions can be inserted as needed in stanchion holes (or stanchion pockets) provided for this purpose. Insertable slats are placed in the longitudinal direction between the stanchions. In order to be able to secure the cargo in  the direction of travel, elements called crossbeams are fastened between two stanchions  transversely to the direction of travel. Bodies with solid sides (box bodies) can also have tie-down eyes inset in the wall. If a very strong endwall is in place, the cargo can be placed against it in ­form-locking manner and secured against sliding forwards such as when the driver brakes. Figure 4.9 shows some common fittings for securing loads.

32

4  Trailers and Semitrailers a

b Stanchions

Pop-up roof

Endwall

Intermediate floor Insertable slats Crossbeam An-slip floor Tie-down eyes Perforated rail in the floor

Fig. 4.9   Equipment for securing loads using the example of a curtainsider; a a photo, b a diagram. (Photo at top: Krone)

4.6  Driver Assistance Systems in Trailers or Semitrailers

33

4.6 Driver Assistance Systems in Trailers or Semitrailers There are driver assistance systems for trailers or semitrailers. Ramp approach aid or reversing aid The ramp approach aid helps the driver to back up to the ramp. It consists of r­ ear-facing sensors (ultrasonic sensors) that measure the distance from an obstruction and/or the loading bay. There are reversing aids that issue an acoustic, haptic or optical alert when the vehicle is close to the obstruction. Fully integrated systems relay information about the distance from the obstruction – as in [12] to the towing vehicle in a standardized format. If the towing vehicle has the corresponding functionality, the distance from the obstacle is displayed on the instrument cluster. Other systems briefly activate the semitrailer or trailer brake at a given distance from the ramp, indicating to the driver that there is still some space between the vehicle and the obstacle. Other systems emit a beeping sound. These systems have an advantage over the fully integrated approach in that the ramp approach aid can perform its function independently of the towing vehicle, but they are less convenient. Telematics systems for trailers Many trailers have a life without the truck. The trailer can be loaded onto trains or ferries without the towing vehicle, or it is parked in a haulage company yard and used as storage space. In these cases, the trailer or semitrailer is not attached to a tractor unit. But the forwarding agent may still benefit from being able to receive and analyze data from it. One minor use case is, for example, trailer tracking. Special telematic systems return data from the trailer independently of the towing vehicle. Of course, this requires a power supply that is also independent of the towing vehicle, so batteries are needed. Temperature monitoring in the cargo area independently of the tractor unit can be an important function that is assured by telematics. Immobilizer for the trailer The immobilizer for the trailer is equipped with a device that blocks the trailer brake. This block can be canceled with a numeric code. Most importantly, this can prevent a trailer from being stolen; but it can also ensure that the driver only drives off the yard with the trailer for which he has received the corresponding numeric code. This is an effective way to prevent mix-ups regarding trailers in large haulage company yards. Telematics can also be used to prevent unauthorized opening of the doors (theft of the cargo), for example: The doors can only be opened (without force) if the corresponding release signal has been transmitted by the fleet. Door control can also be coupled with geographical data. The doors cannot be opened except at predefined locations (geofencing for the cargo).

5

Equipment for Typical Truck Application Areas

The vehicle with body, trailer or semitrailer is usually configured to perform a specific function. The fact that vehicles used for garbage collection would not look like logging trucks or concrete mixers is self-evident. But even semitrailers that appear interchangeable at first sight and are used for transporting seemingly very similar goods often include details that are optimized for particular operational purposes. Particularly the jigs and fixtures for securing loads are often ideally suited to quite specific cargoes. For example, there are special equipment packages for normal pallet goods, bulk boxes used widely in the automotive industry, beverage pallets, barrels, for transporting rolls of sheet metal coils paper rolls and building materials.

5.1 Distribution Transport To enable the distribution transport driver to load and unload his cargo without assistance, many of the vehicles used in this sector are equipped with installations to help with loading and unloading. Platform lifts are mounted on the rear of the vehicle. The cargo can be pushed onto the platform lift (with a pallet jack or dolly) and then raised or lowered. In the position for driving, the platform lift is folded up against the rear of the vehicle or folded down under the rear. Figure 5.1 is a diagram showing how a liftgate works. Before a liftgate is fitted, a check must be carried out to ensure that it is compatible with the vehicle chassis and body. The liftgate has implications for several of the vehicle’s characteristics. These include the axle load distribution, the vehicle length, and also the stress on the frame. When mounting a liftgate, care must be taken not to exceed the associated limit values.

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9_5

35

36

5  Equipment for Typical Truck Application Areas

Liftgate closed

Liftgate opening

Liftgate open and raised

Liftgate open and lowered

Fig. 5.1   Diagram of liftgate function. The variant shown here is folded upwards for driving and serves in place of the cargo space rear-end doors

Truck-mounted forklifts are carried piggyback on the rear of the vehicle to enable the driver to load or unload without having to rely on the forklift trucks available at the loading point. Since the forklift is quite heavy, it reduces the payload that is usable for the cargo.

5.2 Fresh Food Transports An important sector for truck traffic is transporting refrigerated goods. It would really be more accurate to describe this as fresh food transports or temperature-controlled logistics. It is not always a matter of refrigerating the goods. In many cases, the goods must be kept at a defined temperature during transportation, so when in very cold weather the cargo area also has to be heated. Lettuces and other vegetables can be easily damaged if they are kept too cold. Apart from food, pharmaceuticals are another example of products that must be transported in a temperature-controlled environment. Refrigerated transport vehicles have a well insulated cargo space and a refrigeration system that is able to maintain the desired temperature inside the cargo space. The refrigeration temperature and speed with which the loading volume can be cooled down is determined by a number of parameters: • • • • • •

insulation of the body, size and shape of the body, frequency and duration of door openings, efficiency of the refrigeration system, outside temperatures, and temperature and heat capacity of the goods being transported.

The cooling for refrigeration is generated by a cooling unit that gives off heat to the surrounding atmosphere like a refrigerator and has a cold evaporator inside the refrigeration

5.2  Fresh Food Transports

37

compartment. Air is cooled as it flows past this evaporator. The air is kept circulating by a fan. Figure 5.2 shows various positions where the refrigeration unit can typically be installed. The refrigerant circuit is usually powered by electricity. The need for electrical energy surpasses the performance capabilities of most standard on-board electrical systems. So extra generators are needed, with an output of up to 40 kW for large cargo areas. There are basically two systems for driving the generator. An additional, powerful electricity generator is driven by the vehicle’s diesel engine. The drawback of this system is that electricity is only generated when the vehicle’s combustion engine is running. Other systems have their own combustion engine for driving the power generator. This way, the body or trailer can also be cooled when the combustion engine in the towing vehicle is not running, or when the trailer/semitrailer/swap body has been unhitched from the towing vehicle. The drawback of this system is that an additional combustion engine entailing substantial extra cost and weight must be accommodated. The air that has been chilled by the refrigeration unit is circulated in the cargo space through cooling ducts. The cooling ducts are often routed under the cargo space roof. The chilled air descends onto the load. The refrigerated body can be divided into several

Evaporator in the cargo space

Refrigeration unit above the driver's cab

Refrigeration unit under the body

(evaporator in the cargo space)

Refrigeration unit on the leading face of the trailer/semitrailer

Fig. 5.2   Typical positions for installing the refrigeration unit in vehicles for transporting fresh produce. (Photos: Michael Hilgers)

38

5  Equipment for Typical Truck Application Areas

different climate zones so that various products that have to be transported under different temperature conditions can be delivered in one vehicle. Refrigerated bodies are frequently used to transport goods that are subject to strict cleanliness and hygiene requirements. Accordingly, dirt-resistant surfaces that are easy to clean are used. Another equipment feature is a drain in the bottom trough of the refrigerated body so that the body can be wet-cleaned more conveniently. Hanging transport goods A specialized area of refrigerated transportation is the delivery of hanging meat. In order to be able to transport such loads in a hanging position, the walls and roof of the superstructure body must be specially reinforced. Rails are attached below the roof, and hooks are fitted movably in the rails; the hooks carry the hanging goods.

5.3 Dump Truck The most important vehicle in the construction site sector is the dump truck. A tiltable cargo area is mounted on a platform vehicle. A commonly used platform-type vehicle is the three-way tipper. Its cargo area can be tilted hydraulically in three directions (the dumper semitrailer is most often unloaded from the rear, this is called the rear dump). Typical tilt angles to the rear are in the order of about 50°. Models offered range from light dumpers, which are mounted on lighter, two-axle vehicles, up to heavy tipping trucks built on four- or even five-axle chassis. Variants are available with steel and air suspension. In the case of dump trucks with air suspension, the suspension should be lowered before tipping is started, because otherwise the vehicle will bounce abruptly. The dump truck body consists of three basis components [14]: the dump body (the liftable cargo area), the hydraulic system and the subframe – for a description of the subframe please see Sect. 3.1. The hydraulic system includes one or two hydraulic cylinders depending on the size of the dump body. The dump body is available in many different designs: with different material qualities, cargo liftgates of various heights and with different add-on equipment packages. The equipment packages may be, for example, plastic linings on the cargo area to reduce wear or prevent the load from freezing to the body walls and floor, or tarpaulins for protecting the cargo. The covering tarpaulin might be removed and closed manually or with a motor. The cargo liftgate must open to allow the cargo to fall out in a dumping operation. Liftgate solutions exist in which the liftgate folds downwards, there are gullwing doors (in the rear), and the most practical solution, the pendulum tailgate. During a tipping operation, the pendulum tailgate automatically swivels about its top edge under the force of gravity and opens up a gap between the cargo area and the end panel. When traveling, the end panel is locked to prevent it from opening unintentionally. The lock is opened and closed manually or hydraulically. To enable the dump body to be emptied gradually

5.4  The Tank/Bulk Sector

39

and in measured quantities, some liftgates have an extra, smaller opening that is opened and closed by a slide valve (grain chute). For use in road construction, dump trucks are equipped with an upwardly folding rear underride guard. When the underride guard is folded up, the road paver (popularly known as the tar spreader) can push the dump truck in front of itself. Meanwhile, the dump truck continuously deposits its load into the hopper on the paver. A dump truck configuration can be combined with additional bodies such as a crane body so that the dump truck can load itself. Vehicles of this kind are commonly in service in the municipal works sector, or with gardening and landscaping businesses.

5.3.1 The Tractor Semitrailer Combination in Construction Besides the vehicles built purely for construction site work, more and more t­ractor/semitrailer combinations are also appearing on building sites. A combination with dumper semitrailer provides greater load capacity – about 6 t more – than a four-axle construction site vehicle. In Europe, the four-axle vehicle has a permissible gross vehicle weight of 32 t and a dead weight of more than 12 t, so it is permitted to carry less than 20 t. The three-axle dumper semitrailer weighs about 6.5 t, the tractor unit roughly another 7.5 t. So with a permissible gross vehicle weight of 40 t the semitrailer can hold about 26 t. And the fleet can use the tractor unit in many more varied roles than a vehicle designed solely for building site work. For example, a combination for use on the building site may be fitted with a hydraulic front axle for improved traction. However, the semitrailer combination is not as rugged and performs less well off-road, so it tends to be used in less harsh roles on the construction site. The purpose-built construction site truck is rightfully preferred for rough terrain work.

5.4 The Tank/Bulk Sector In the tank/bulk sector, the largest possible amount of cargo is usually limited by the fact that the vehicle’s weight limit is reached. Consequently, efforts to build lighter vehicles for this sector are never ending. Customers are happy to buy lightweight options (see Sect. 2.1).

5.4.1 Transport of Liquids in Tankers Tankers are needed for transporting liquids. Typical goods for transportation include petroleum products such as gasoline, diesel, heating oil and chemicals, but also edibles such as milk and wine.

40

5  Equipment for Typical Truck Application Areas

To minimize sloshing motion in the tank (unpleasant and potentially dangerous when driving), the tanks are divided into partitions by baffle plates. To prevent the liquid from freezing up, many tank containers are insulated. Many carry the equipment they need for draining the liquid on-board. These include pumps, hoses and flowmeters, etc. Milk tankers that collect milk from farming businesses are typically also equipped with an on-board pump for filling.

5.4.2 Bulk Transports For granulates, small diameter materials, powders (free-flowing bulk solids) and powdery or dust-like goods, bulk tanks are used. The individual vehicles differ in terms of the volume and number of chambers according to their specific purpose. The containers are normally filled via filling ports on the top of the container. These are closed by large covers. The filler holes are usually large enough for a man to climb through (when the container is empty, of course) which is helpful for cleaning. This is why they are called manholes. To open and close the filling ports, bulk vehicles typically have a bar on the top of the container, which is reached by a ladder. The container is emptied through funnels to which hose or piping systems can be connected. Since gravity alone is often not enough to drain the cargo – or the draining process takes place too slowly by gravity alone – it is assisted by a pneumatic system. The air is blown into the container and forces the cargo out. Very sticky cargo requires additional measures to ensure that as little as possible is left behind after draining. For this, the displacement air is blown into the cargo at several points, for example, or vibrational systems are provided which loosen the cargo mechanically. Particularly in the semitrailer sector, tiltable bulk containers are also used. One (or more) hydraulic cylinders raise the container; typical tilt angles are in the order of 45°. The vehicle must be stabilized during the tilting operation; so many (but not all) semitrailers with a tilting capability have supports that are extended mechanically or hydraulically. Pumps are needed for the pneumatic system (unloading) and the hydraulic system (tilting).

5.5 Transport by Sea Container The road transport of sea containers that travel all over the world on large container ships is a special application in the trucking business. At the port, the containers are loaded onto trucks or trains and then transported inland to their intended destinations. Sea containers are standardized according to ISO 668 [20] – see also Table 5.1.

5.5  Transport by Sea Container

41

Table 5.1  Typical containers according to ISO 668 [20]. The smaller containers are slightly shorter than their nominal description suggests; accordingly, for example, two 20-foot containers can fit in the bay for a 40-foot container, although the boundary surface is a little uneven Description

Sector according to ISO 668

Container length according Arithmetical lengtha (m) to ISO 668 (m)

10 ft

1D…

2.991

3.048

20 ft

1C…

6.058

6.096

30 ft

1B…

9.125

9.144

40 ft

1A…

12.192

12.192

45 ft

1E…

13.716

13.716

aOne

foot is equal to 0.3048 m

Fig. 5.3   Semitrailer chassis for transporting 40-foot sea containers. The trailer shown is optimized for minimum dead weight. Several twistlock closures are visible – on the rear, on the front and in the middle. (Photo: Kögel)

The containers have standardized corner casting that include stable fitting molds for twistlock fastening. The twistlocks are a kind of rod that engages in the fitting molds on the corner castings and secure the container in place when twisted. To enable a semitrailer to be used for various container types, container chassis are produced with twistlock fastenings at various points so that the various container types can be accommodated. Extendable container chassis can be extended or shortened to fit the length of the container that is to be transported. Figure 5.3 shows a semitrailer chassis for transporting sea containers that is optimized for minimum dead weight. The perforated longitudinal members, omission of various equipment options and the rather slender construction all help to reduce weight.

Comprehension Questions

The comprehension questions serve to test how much the reader has learned. The answers to the questions can be found in the sections to which the respective question refers. If it is difficult to answer the questions, it is recommended that you read the relevant sections again. A.1 Curb weight a. Why does the vehicle operator want a lighter vehicle/ a lighter vehicle combination? b. How can a vehicle be made lighter? A.2 Power supply to the body How is the body supplied with power by the vehicle (two answers)? A.3 Vehicle combinations Name several different vehicle combinations. A.4 Tractor semitrailer combinations a. Which sectors of the user community prefer tractor semitrailer combinations and which prefer platform vehicles? b. Now you can use your imagination! What do you think are the reasons for this? A.5 Self-loading What equipment can be included on the vehicle to assist with loading? A.6 Refrigeration a. What problems occur if it is very cold? b. What can be done about the aforementioned problems?

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9

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Abbreviations and Symbols

The following is a list of the abbreviations used in this booklet series. The letters assigned to the physical variables is in conformity with the normal usage in the engineering and natural sciences. The same letter can have different meanings depending on the contexts. For example, lower case c is a very busy letter. Some abbreviations and symbols have been subscripted to avoid confusion and improve the readability of formulas, etc.

Lowercase Latin letters a acceleration c coefficient, proportionality constant cd coefficient of aerodynamic drag cT coefficient of drag with oblique incident flow da abbreviation for deca = 10, the force specification daN (deca-Newton) being particularly popular because 1 daN = 10 N, which is approximately equal to the weight force of one kilogram on Earth f coefficient or correction factor g gram—unit of mass g gravitational acceleration (g = 9.81 m/s2) h height (measure of length) i transmission ratio, rotational speed ratio k kilo  = 103 = multiplication factor of 1000 kg kilogram—unit of mass kW kilowatt – unit of power; one thousand watts kWh kilowatt-hour—unit of energy l length l liter, unit of volume; 1 l = 10−3 m3 m mass or meter or milli = 10−3 = a thousandth part

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46

Abbreviations and Symbols

p pressure r radius (measure of length) s route (linear measurement) t ton – Unit of mass; 1 t = 1000 kg v speed

Uppercase Latin letters A area, particularly frontal face area ABS anti-lock braking system (brakes) BGL Bundesverband Güterkraftverkehr, Logistik und Entsorgung e. V. (German federation for road haulage, logistics and disposal) C degree Celsius – unit of temperature C coulomb – unit of charge CAN controller area network CO2 carbon dioxide DEF diesel exhaust fluid (AdBlue) DIN Deutsches Institut für Normung (German institute for standardization) E energy ECU electronic control unit EMC electro-magnetic compatibility EPB electro-pneumatic brake ESP electronic stability program F force FG gravitational force GPS global positioning system J joule, unit of energy K kelvin, unit of temperature on the Kelvin scale LED light emitting diode LIN local interconnect network M torque M mega  = 106 = Million MJ megajoule, unit of energy—one million joules OEM original equipment manufacturer PTO power take off P power R gas constant T temperature (in Kelvin oder °C) TCO total cost of ownership incurred over the usage duration of a vehicle or of another asset

Abbreviations and Symbols

V volume W mechanical work or mechanical energy W watt, unit of power

Lowercase Greek letters α angle β angle γ angle µ stands for micro = 10−6 = a millionth ρ density ω angular velocity or rotating speed

Uppercase Greek letters Θ temperature

47

References

1. Hilgers, M.: Entire Vehicle. Commercial Vehicle Technology. Berlin/Heidelberg/New York: Springer (2021) 2. Hilgers, M.: Chassis and Axles. Commercial Vehicle Technology. Berlin/Heidelberg/New York: Springer (2021) 3. Hilgers, M.: Electrical Systems and Mechatronics. Commercial Vehicle Technology. Berlin/ Heidelberg/New York: Springer (2021) 4. Daimler: Press release: Weltpremiere für den ersten Lkw speziell für den schweren Verteilerverkehr. (World premiere for the first truck designed especially for heavy distribution haulage.) Daimler Communications, July 2, 2012 (2012) 5. Straßenverkehrs-Ordnung [Road Traffic Regulations] of March 6, 2013 (2013) published in the German Law Gazette (BGBl. I p. 367) (2013) 6. German Law Gazette 2013 Part I No. 12, issued in Bonn on March 12, 2013 – Page 367 and following: Ordinance on amended version of the Road Traffic Regulations (StVO) of March 6, 2013 (2013) 7. ISO337, Road vehicles – 50 semi-trailer fifth wheel coupling pin – Basic and mounting – interchangeability dimensions 8. ISO1726, Road vehicles – mechanical coupling between tractors and semi-trailers – interchangeability 9. ISO4086, Road vehicles – 90 semi-trailer fifth wheel kingpin – Interchangeability 10. SAE J560 Primary and Auxiliary Seven Conductor Electrical Connector for ­Truck-Trailer Jumper Cable 11. ISO12098, Road vehicles – Connectors for the electrical connection of towing and towed vehicles – 15-pole connector for vehicles with 24V nominal supply voltage 12. ISO11992, Road vehicles – Interchange of digital information on electrical connection between towing and towed vehicles – Part 1 to 4 13. Mercedes-Benz: Body guidelines for trucks – available for download from the internet (2011). http://www.mercedes-benz.de. Body builders' portal – subject to continuous update 14. Mercedes-Benz: Kipperausstattungen ab Werk Wörth, Meiller: Dreiseitenkipper. Product brochure (2009) 15. Jost-Werke Neu-Isenburg: Produkte für Sattelzugmaschinen, Sattelauflieger, Anhänger – available for download from the internet (2013). http://www.jost-world.com. Accessed Dec. 2013 16. BPW Bergische Achsen Kommanditgesellschaft: BPW Verbindungseinrichtungen für Zentralachsanhänger und Drehschemelanhänger – available for download from the internet (2013). http://www.bpw.de. Accessed Dec. 2013

© Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Hilgers and W. Achenbach, Vocational Vehicles and Applications, Commercial Vehicle Technology, https://doi.org/10.1007/978-3-662-60844-9

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50

References

17. Jost -Werke Neu-Isenburg: Rockinger, Produkte für Nutzfahrzeuge – available for download from the internet (2015). http://www.jost-world.com. Accessed Mar. 2016 18. DAF: Body guideline DAF LF, CF and XF105 – available for download from the internet (2011). http://www.daf.com. Subject to continuous updating 19. Scania bodybuilder homepage http://www.scania.com – Information for bodybuilders – subject to continuous updating 20. ISO668, Series 1 freight containers – Classification, dimensions and ratings

Index

A A-frame towbar, 22 Air suspension, 26 Angles of approach/departure, 6 Anti-slip floor, 31

B Ball hitch, 24 Boat tail, 29 Body builder, 13 Brake in the trailer, 26

C Center axle trailer, 19, 24 Cold weather, 7 Commercial vehicle, 1 Connection, electronic, 25 Construction site, 6 Container, 40 Crossbeam, 31 Curb weight, 3 Curtainsider, 30

D Distribution transport, 35 Distributor vehicles, 5 Drawbar, 22 Drawbar combination, 22 Drop center, 5 Dump body, 38 Dump truck, 38

E Equipment package, segment-specific, 6

F Fifth wheel coupling, 20 Fire truck, 11 Firewall, 31 Fording depth, 6 Free-flowing bulk material, 40 Fresh food transport, 36

G Geofencing, 33 Goods, fine particulate, 40 Gradeability, 6 Ground clearance, 6 Guidelines for the body builder, 15

H Hub odometer, 29

I Immobilizer, 33 Industry, 3 Insertable slat, 31 Integration, electronic, 15

J Jaw-type coupling, 22

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52 K Kingpin, 20

L Large-volume transports, 4 Lift axle, 27 Liftgate, 35 Lift system for the roof, 30 Lightweight construction, 39 Live floor system, 30 Load, 3 Load securing, 27, 31 Loading crane, 31 Loading for rail transportation, 28 Loading height, 4 Logistics, temperature-controlled, 36 Low-liner, 4

M Mobile crane, 31

O OEM, 1 Off-road, 7

P Pallet boxes, 27 Pendulum tailgate, 38 Pintle assembly, 24 Power take-off, 17

Index Side paneling, 28 Snow, 9 Stanchion, 27, 31 Starting response, 8 Steel spring suspension, 26 Stowage boy, 27 Subframes, 14 Support foot, 21

T Tank/silo sector, 39 Tanker, 39 Telematics system, 33 TEM, 13 Three-way tipper, 38 Through-loading trailer, 24 Tie-down eye, 31 Traction, 6 Traction assistance, 9 Tractor semitrailer combination, 19 Tractor semitrailer combination in construction, 39 Trailer, 19 Transport goods, hanging, 38 Transport task, 1 Truck-mounted forklift, 36 Turntable, trailer, 19

U Unmade roads, 6

V Vehicle variant, 1 R Ramp approach aid, 33 Ramp breakover angle, 6 Rear-end door, 30 Rear wing, 29 Refrigeration unit, 36 Roll-up gate, 30

S See container, 40 Semitrailer, 19

W Winter, 7 Work task, 1