by Harald Abendroth, Yosuke Sasaki and Carlos Agudelo

The braking and steering systems found in modern cars and trucks are crucial to allowing drivers to remain in control of the speed and direction of the vehicle while avoiding hazards.

Increasingly integrated with vehicle electronics, braking and steering controls are the most significant active safety systems in today's vehicles, and they prevent injuries and property damage everywhere in the world. This is why international technical and regulatory bodies focus so much on the performance of these systems and their critical components.

Whether they are drum or disc type, the friction brakes used in today's cars and trucks are crucial to vehicle and road safety. Friction materials work every time a driver needs to slow a vehicle, come to a complete standstill, keep the speed stable when going downhill, or hold a vehicle stationary on a grade.

Developers of friction brake linings must also consider durability, environmental effects, mechanical properties, and noise, vibration and harshness (NVH). Normal brake operating temperatures are in the range of 150-300°C, but brakes must be able to function at unusual temperatures as well - up to 800°C under heavy loads or during mountain driving.

Some brake linings last as much as 100 000 km when driving on paved, smooth highways, while others may require replacement almost every month on a taxicab driving on hilly roads.


Typical brake system layout

Industry and societal impact

An estimated 600 million vehicles were on the world's roads in 2008, helping to move people and the economy every day - and that figure is projected to double to 1.2 billion by 2050. With the rapid economic growth concentrated in the developing world - and especially the BRIC countries (Brazil, Russia, India, and China) - the current trend is expected to generate a three-fold increase in the number of vehicles by 2020 compared to 1995 in those countries.

But this social and technical development comes with an unacceptable price to society : 1.3 million deaths per year, 90 % which occur in developing countries. Some 37 000 people die each year in traffic accidents in the USA, and almost 700 per day in India. Injury estimates
range as high as 50 million per year worldwide. Without concerted efforts by governments and industry, traffic accidents will be the leading cause of death among children aged five to 14 by 2015.


In the USA, a motorcyclist involved in a crash with a passenger car is almost 40 times more likely to die than the driver of the automobile. A passenger car driver colliding with a heavy truck is almost five times more likely to die. The economic cost of traffic accidents is estimated to exceed USD 500 billion each year, with more than 200 billion of those in the USA.

But European statistics show that it is possible to achieve better safety. Sweden's VisionZero programme, for instance, is at least partly responsible for a dramatic reduction in traffic fatalities among children - from some 1 300 deaths per year in the mid-1960s to 397 in 2008 - despite a significant population increase and far more vehicles on the roads.

Aiming to curb these damaging trends to the economy and society as a whole, ISO has joined several long-term programmes together with the United Nation's Global Ministerial Conference on Road Safety, the World Forum for Harmonization of Vehicle Regulations (WP.29) and the World Health Organization (WHO).

The successful implementation of road safety policies and programmes requires the systematic development and continuous quality control of friction materials (disc brake pads and drum brakes fitted on every passenger car, truck, and commercial vehicle) using International Standards. To accomplish this, more than 100 experts and engineers from around the world developed the ISO 15484 standard over the course of almost 10 years.

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This article was originally published in June 2010 in ISO Focus and has been republished with permission.

About ISO Focus

ISO (International Organization for Standardization) is the world's largest developer and publisher of International Standards.

ISO is a network of the national standards institutes of 163 countries, one member per country, with a Central Secretariat in Geneva, Switzerland, that coordinates the system.

ISO is a non-governmental organization that forms a bridge between the public and private sectors. On the one hand, many of its member institutes are part of the governmental structure of their countries, or are mandated by their government. On the other hand, other members have their roots uniquely in the private sector, having been set up by national partnerships of industry associations.

About the authors

Harald Abendroth is Chair of ISO/TC 22/SC 2/WG 2, Friction materials. Prior to becoming a consultant, he was the Director of Test and NVH at Honeywell Friction Materials for 30 years. Mr. Abendroth has contributed to the development of numerous test standards used throughout the industry.
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Yosuke Sasaki retired from Akebono Brake Industry, Co., Ltd. in 2009, and has served as Japan expert of JSAE for ISO/TC 22/SC 2/WG 2, Friction materials, for seven years. Mr. Sasaki was an R&D Engineer for Friction Materials at Akebono Group for 43 years. He co-chaired the friction materials subcommittee of JSAE for 2 years and was an active member for
13 years.
e: yosasaki@poplar.ocn.ne.jp

Carlos Agudelo is Chief Engineer for Laboratory Testing at Link Engineering Company of Detroit, Michigan. Link designs and manufactures testing systems and provides third-party testing for brake and transmission. Mr. Agudelo manages brake laboratory testing; participates on several SAE, ISO committees, and is a liaison to ISO/TC 22/SC 2/WG 2.
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