Steering Handbook

Frontmatter

Chapter 1. Introduction and History

Abstract

The main advantage of automobiles over the railway is that the driver determines the trajectory of the vehicle. In other words, motor vehicles can be steered and are not tied to any defined track.

Peter Pfeffer, Hartmut Ulrich

Chapter 2. Basic Principles of the Steering Process

Abstract

When we drive a car we do not really think about the steering process and the lateral control of the vehicle. Driving has become a natural and familiar action. In our childhood we learn and internalize this complex process on a tricycle or in a bobby-car. Without any conscious thought, our reflexes control all the actions we perform to drive the vehicle. But modern axle kinematics and power steering systems are the result of over a century of continuous optimization. And yet, the automotive press frequently criticizes the steering characteristics of motor vehicles.

Peter Pfeffer, Jens Holtschulze, Hans-Hermann Braess

Chapter 3. Steering Requirements: Overview

Abstract

The decision to buy a new car is significantly influenced by the customer’s subjective impression when driving. Here, the chassis exerts a critical influence on driveability.

Sina Brunner, Manfred Harrer

Chapter 4. Steering Kinematics

Abstract

There are different basic methods how to control the direction of a car purposefully. Wheeled cars with pneumatic tyres may have integrated Swinging beam, buckling or axle-pivot steering. The first two types suffer the disadvantage that their footprint shrinks when steering and interfering forces will act on a lever arm that corresponds to half a tyre track. Moreover, either the front or rear tyres or all the tyres together may be steered. For high-speed cars, however, a third design is favoured: axle-pivot steering on the front axle. Therefore, only this type will be considered here. The rotational axis of the Wheel carrier, or “Stub axle”, on the wheel suspension (e.g., a “kingpin”) is usually steady when the car is steered (pure rotation of the tyre trunk); however, there are now many cars whose suspensions feature a variable (“virtual”) axis of rotation.

Michael Trzesniowski

Chapter 5. Basics of Lateral Vehicle Dynamics

Abstract

This chapter is an introduction to lateral vehicle dynamics and steady and dynamic cornering. Basic discussions will serve to analyse the essential factors influencing the lateral vehicle dynamics of a car and the steering wheel angle and torque indicated by the driver. Models are required for a more detailed analysis, they expand upon the fundamental relationships for slow and fast cornering (see Chap.​ 2). Steady-state circular driving will be discussed based on the linear single track model. This leads to dynamic cornering. We do this the classic way by applying analytic equations. Their big advantage is that the relationships may be easily understood. When the effects of shifting the dynamic wheel load will be included, the single track model has to be extended into a Dual-track model. This is usually done using numerical simulations, because closed equations serve little to illustrate these relationships.

Peter Pfeffer, Hans-Hermann Braess

Chapter 6. Acoustics and Vibrations

Abstract

Acoustics and Vibration technology for car development has gained significance and made major progress over the last few years. Sound patterns and volume of noises, as well as frequency and volume of car vibrations have to be considered while the car is being developed. Noises perceived as unpleasant should be very faint while warning noises have to be loud enough to meet certain safety standards. In addition, the noises of middle class and superclass cars are ‘designed’ in such a way that they correspond to what the customers expect. This is also true for any noticeable vibrations. The driver is in contact with the wheel and feels any vibrations occurring there at all times. The design of these vibrations of the steering wheel, including mounted parts and body, with regard to comfort is a major task. How acoustics and vibrations are perceived is an increasingly important argument for the decision to purchase.

Stefan Sentpali, Rupert Hintersteiner

Chapter 7. Steering-Feel, Interaction Between Driver and Car

Abstract

Steering-feel, from German lenkgefühl, is a driver’s subjective sensation when steering a vehicle. This steering-feel derives from the perception and assessment of steering behaviour and thus the drivability; it embodies the interaction between car and driver. The drivability generally consists of a vehicle’s response to the driver’s input, as well as external interferences, such as crosswind or uneven road surfaces. The steering behaviour is part of the overall drivability, and describes vehicle response to steering input as well as interferences.

Manfred Harrer, Peter Pfeffer, Hans-Hermann Braess

Chapter 8. Layout of Steering Systems

Abstract

Excellent driving and steering feel can be achieved only by a sufficiently precise steering system. Therefore, on the one hand, the design of a steering system has to be able to transfer high forces while on the other hand achieving little free travel, few elasticities and low friction in the movable parts. In addition, the steering system, supported by its power-assistance unit, should be able to realize sufficient steering dynamics. Adhering to these constraints is the only way to enable quick and precise steering of a car. In the following chapters the basic functional design of steering systems and the aspects of steering power and friction will be discussed in more detail.

Sina Brunner, Manfred Harrer, Manuel Höll, Daniel Lunkeit

Chapter 9. Steering Wheel

Abstract

The driver perceives the steering wheel as one of the first parts inside a car. It is one of the most important interfaces between man and machine, because the steering movements are initiated at the steering wheel and the driver receives a direct response on the driving situation.

Markus Walters

Chapter 10. Steering Column and Intermediate Steering Shaft

Abstract

The basic function of steering column and intermediate steering shaft is to establish the mechanical link between steering wheel and steering gear. The steering wheel and the torsion bar of the steering gear are linked in such a way that any rotation initiated at the steering wheel will be converted almost without loss or backlash. Torques issued from the steering gear are likewise converted to the steering wheel. The connecting elements, steering column and intermediate steering shaft, hence, affect the driveability and the perceptible contact with the road. Beside this basic mechanical function, there are now various other demands to both subassemblies.

Jörg Hauhoff, Ralf Sedlmeier

Chapter 11. Mechanical and Hydraulic Gears

Abstract

The family of steering equipment covers hydrostatic steering systems, recirculating ball-with-nut gears, manual rack-and-pinion steering and rack power steering. The final steering system mentioned has a rack-and-pinion gear which transforms the rotation of the steering wheel into the translation of the rack and again into the steering movement of the tyres.

Johannes Hullmann, David James, Alois Seewald, Eduard Span, Alexander Wiertz

Chapter 12. Tie Rods

Abstract

The tie rod connects the steering gear with the wheel carrier and transfers the gear stroke to wheel carrier and front wheel.

Dirk Adamczyk, Wolfgang Kleiner, Dirk Maehlmann

Chapter 13. Hydraulic Power Supply

Abstract

Hydraulically supported steering systems have been a standard of the car industry for many years, being state-of-the-art even in compact cars. The open centre steering system with a volumetric flow-controlled vane-type pump has prevailed against other possible steering systems, essentially because of its price. This steering system is questioned, though, by the very heated debate about energy conservation. Power-saving hydraulic systems are advancing, hence, because the power dissipation of a limited vane cell can no longer be neglected. These systems will be discussed in the following.

Dieter Semmel

Chapter 14. Electrically Powered Hydraulic Steering

Abstract

Electrically powered hydraulic steering (EPHS) was developed in the early 1990s from the demand for power-saving steering systems which can be controlled independently from the internal combustion engine. The capabilities of these systems has been successively expanded.

Jochen Gessat, Alois Seewald, Dirk Zimmermann

Chapter 15. Electric Power Steering Systems

Abstract

A change of hydraulic systems to solely electrically operated steering systems (Electric Power Steering, EPS) has taken place in passenger car steering systems during the last years.

Alexander Gaedke, Markus Heger, Michael Sprinzl, Stefan Grüner, Alexander Vähning

Chapter 16. Superimposed Steering System

Abstract

The growing number of mechatronics options in the field of steering systems provides additional steering functions. One of them is the superimposed steering system. A heterodyne angle is added to the driver’s steering input by a specific superposition of the steer-angle. This enables additional steering functions, for example, a VGR or steering dynamics and steering stabilisation functions. Combined with a superposed steering torque, functions that are otherwise reserved to steer by wire, such as freely programmable steering functions, may be enabled.

Mirko Reuter, André Saal

Chapter 17. All-Wheel Steering

Abstract

Various steering systems that apply a steer-angle at the front wheels to perform their driving task were described in the preceding chapters. All-wheel steering also provides the possibility to make the back wheels steerable, in addition to the steering at the front axle.

Peter Herold, Markus Wallbrecher

Chapter 18. Steer by Wire

Abstract

Steer by Wire is an automotive system that electrically transmits a steering command from an operating element (steering wheel) by an ECU to an actuator executing the steering command at the driven wheels. These systems do not have any mechanical connection between steering wheel and driven wheels. To improve handling, the driving state delivers a haptic response to the driver by an active operating element.

Pei-Shih Huang, Alfred Pruckner

Chapter 19. Overview: Driver Assistance System Functions

Abstract

The continuing increase of road traffic and rising demands to the driver have produced a huge number of assistance systems during the last years. They all support the driver’s task of driving. There are systems for keeping the course which engage the brake or the driveline. It seems reasonable to include the steering into this purpose as well.

Stefan Brosig, Markus Lienkamp

Chapter 20. Outlook: The Future of Steering Systems

Abstract

The authors firmly believe that in spite of increasing constraints, individual driving and steering of cars will still be prevalent in 2025 and beyond, and that the joy of driving will continue to be of primary importance. This means that current functions in the steering system technology will remain in focus for long term development within the dedicated development departments of vehicle and steering system developers, so that the brand specific steering feel which the driver and customer expects will be maintained in the future as well. To conclude, the authors want to assess various aspects of automotive construction connected to steering system response.

Manfred Harrer, Peter Pfeffer

Backmatter