Browse Topic: Brake linings

Items (286)

Driveline Parking Brake Test Procedure for Medium Duty Vehicles

J2690_202110 (Current)

10/28/2021

This SAE Recommended Practice establishes uniform test procedures for friction based parking brake components used in conjunction with hydraulic service braked vehicles with a gross vehicle weight rating greater than 4500 kg (10 000 lb). The components covered in this document are the primary actuation and the foundation park brake. Various peripheral devices such as application dashboard switches or indicators are not included. These test procedures include the following: a Brake Related Tests 1 Brake Functional Performance 2 Brake Dynamic Torque Performance 3 Brake Corrosion Resistance 4 Brake Endurance with Torque 5 Brake Endurance without Torque 6 Vibration Resistance 7 Brake Ultimate Static Load 8 Brake Lining Wear Adjuster Function b Actuation Related Tests 1 Mechanical Actuator Functional Performance 2 Mechanical Actuator Endurance 3 Mechanical Actuator Quick Release 4 Mechanical Actuator Ultimate Load 5 Spring Apply Actuator Functional Performance 6 Spring Apply Actuator Operating Temperature Range 7 Spring Apply Actuator Endurance 8 Spring Apply Actuator Corrosion Resistance 9 Spring Apply Actuator On-Off Switch 10 Spring Apply Actuator Vibration

Truck and Bus Hydraulic Brake Committee

Brake Lining Quality Test Procedure

J661_202110 (Current)

10/26/2021

The purpose of this SAE Recommended Practice is to establish a uniform laboratory procedure for securing and reporting the friction and wear characteristics of brake linings. The performance data obtained can be used for in-plant quality control by brake lining manufacturers and for the quality assessment of incoming shipments by the purchasers of brake linings.

Brake Linings Standards Committee

Service Maintenance of SAE J1703 and SAE J1704 Brake Fluids in Motor Vehicle Brake Systems

J1707_202106 (Current)

6/10/2021

This SAE Recommended Practice provides basic recommendations for dispensing and handling of SAE J1703 and SAE J1704 Brake Fluids by Service Maintenance Personnel to assure their safe and effective performance when installed in or added to motor vehicle hydraulic brake actuating systems. This document is concerned only with brake fluid and those system parts in contact with it. It describes general maintenance procedures that constitute good practice and that should be employed to help assure a properly functioning brake system. Recommendations that promote safety are emphasized. Specific step-by-step service instructions for brake maintenance on individual makes or models are neither intended nor implied. For these, one should consult the vehicle manufacturer’s service brake maintenance procedures for the particular vehicle. Vehicle manufacturer’s recommendations should always be followed.

Brake Fluids Standards Committee

Air Brake Performance and Wear Test Code Commercial Vehicle Inertia Dynamometer

J2115_202008 (Current)

8/20/2020

This SAE Standard provides test procedures for air and air-over-hydraulic disc or drum brakes used for on-highway commercial vehicles over 4536 kg (10000 pounds) GVWR. This recommended practice includes the pass/fail criteria of Federal Motor Vehicle Safety Standard No. TP-121D-01.

Truck and Bus Foundation Brake Committee

Truck and Bus Grade Parking Performance Test Procedure

J360_202008 (Historical)8/19/2020

Truck and Bus Brake Systems Committee

Measurement of Copper and Other Elements in Brake Friction Materials

J2975_202007 (Current)

7/23/2020

This procedure describes a method for generating, preparing and analyzing samples of new and unused brake friction materials for their chemical constituents.

Brake Linings Standards Committee

Regressions of brake pads compressibility from experimental data

2019-36-00141/13/2020

One of the critical characteristics in a brake pad is its deformation when subjected to compressive loads. This deformation is called compressibility, which can be obtained quantitatively through compression cycles performed by a specific test bench. However, such testing is costly and long enough not to meet the demand of manufacturers of friction materials. To overcome this difficulty, this work presents regressions for the estimation of compressibility through the natural frequencies of the pads, since they can be obtained quickly and at low cost through a simple modal analysis. The theoretical basis for the correlation between compressibility and natural frequencies includes the theory of elasticity - which defines an inverse relationship between strain and stiffness - and the theory of vibrations, which defines the natural frequencies of a mechanical system as a function of its mass matrices and stiffness. Since the dependent variable (compressibility) and explanatory variable (natural frequency) are linked to stiffness, it is theoretically plausible to direct estimative. As additional explanatory variables, in addition to the experimental data of natural frequencies, the work uses the mass values and the temperature during the natural frequency measurement to improve the regression models.

Suetti, André Garcia Lima

Road Vehicles - Friction Materials - Finished Brake Pad Normalized Elastic Constant of Friction Material

J3175_201911 (Current)11/20/2019

This SAE standard specifies a method for testing and measuring a normalized elastic constant of brake pad assemblies using ultrasound. This document applies to disc brake pad assemblies and its coupons or segments used in road vehicles.

Brake Linings Standards Committee

Divergence of Thickness Loss vs. Weight Loss, Friction and Wear Behavior of Heavy Truck Brake Blocks: Development of a New Test Procedure for the Chase Tester

2019-01-21079/15/2019

Heavy truck brake blocks are found to swell (or expand) permanently during testing or usage, especially so at high temperatures, thus leading to longer durability as measured by thickness loss, similar to light vehicle disc pads. This swelling phenomenon occurs continuously in the layer adjacent to the friction surface during testing or usage; not a one time event. The thickness loss estimated from the weight loss is always greater than measured thickness loss. Brake block wear does not increase linearly with increasing normal load, and the load-sensitivity of block wear is very much dependent on the products. A new test procedure has been developed for generating friction-vs.-temperature and wear-vs.-temperature data at a constant temperature employing intermittent braking on the Chase Brake Lining Quality Tester (SAE J661) and friction material wear can be compared on equivalent-work basis.

Rathee, Aman, Sharma, Devendra Kumar, Singh, Shivraj, Rhee, Seong Kwan

The Normal-Load and Sliding-Speed Dependence of the Coefficient of Friction, and Wear Particle Generation Contributing to Friction: High-Copper and Copper-Free Formulations

2019-01-21319/15/2019

Automotive brakes operate under varying conditions of speed and deceleration. In other words, the friction material is subjected to a wide range of normal loads and sliding speeds. One widely accepted test procedure to evaluate, compare and screen friction materials is the SAE J2522 Brake Effectiveness test, which requires full-size production brakes to be tested on an inertia brake dynamometer. For the current investigation, disc pads of two types of 10 different formulations (5 high-copper and 5 copper-free formulations) were prepared for testing on a front disc brake suitable for a pickup truck of GVW 3,200 kg. Each pad had 2 vertical slots, and one chamfer on the leading edge and also on the trailing edge of the pad. One segment of the test procedure looks at the coefficient of friction (Mu) under different brake line pressures and different sliding speeds to determine its stability or variability. In all cases, the Mu is found to be dependent on the normal load and sliding speed, contrary to the commonly called “Amontons-Coulomb’s Laws of Friction”. According to Wikipedia, Guillaume Amontons (1663 - 1705) observed that the force of friction was directly proportional to the applied load, meaning constant coefficient of friction and that the force of friction was independent of the apparent area of contact, while Charles-Augustin de Coulomb (1736 - 1806) observed that when a piece of metal was slid against wood, the coefficient of friction became very dependent on the normal load and the sliding speed and warned about the limitations of Amontons’ findings. Now one wonders how and when the expression of the so-called “Amontons-Coulomb’s Laws of Friction” surfaced as universal laws. According to analysis of the test data generated in this investigation, the average Mu is found to increase linearly with the increasing total wear rates of the disc and the 2 pads (the inboard and the outboard pads) in the case of copper-containing formulations and also in the case of copper-free formulations: each type of formulation has its own linear relationship. The average Mu is found to consist of 2 parts. One part is dependent on the total wear rates of the disc and the 2 pads while the other part, which is the Mu at zero wear, is independent of the wear rates. Also in this investigation, the disc wear rate is found to be directly proportional to the total wear rate of the 2 pads (the inboard and the outboard). As the pad wear is reported to be best described by a power function of the normal load and the sliding speed, a power function becomes applicable to the disc wear rate as the disc wear rate is proportional to the pad wear rate. So the wear dependent part of the Mu becomes a power function of the normal load and the sliding speed.

Rhee, Seong K., Sriwiboon, Meechai, Tiempan, Nipon, Kaewlob, Kritsana

Brake Block Effectiveness Rating

J1802_201906 (Current)6/6/2019

Truck and Bus Foundation Brake Committee

Friction Coefficient Identification and Environmental Marking System for Brake Linings

J866_201903 (Current)3/11/2019

Brake Linings Standards Committee

High-Preload Deflection and Compressibility Test Procedures for Friction Materials

J2468_201811 (Current)11/12/2018

This standard specifies a method for testing and measuring the deflection of friction materials assemblies and compressibility of friction materials. This standard applies to disc brake pad assemblies and its coupons or segments, brake shoe lining and its coupons or segments, and brake blocks segments used in road vehicles. This SAE test method is consistent in intent with the ISO 6310 and the JIS 4413.

Brake Linings Standards Committee

Properties and Limitation of an Oxide Coated Aluminum Brake Rotor

2018-01-187710/5/2018

The electrification of the powertrain and the thereto related recuperation of the electric engine saves the energy in the battery and thus reduces the thermally dissipated brake energy, which leads to lower brake rotor temperatures compared to combustion engine vehicles (ICEVs). These new conditions enable to reconsider brake disc concepts. Including lightweight design in heavy battery electric vehicles (BEVs) and the increasingly reliant corrosion resistance of brake rotors, Aluminum is a promising approach for new brake disc concepts. In the past, Aluminum brake disc concepts have already been deployed. For instance Aluminum Metal-Matrix Composite (Al-MMC) concepts in the Lotus Elise S1 and on the rear axle of the Volvo V40 [1]. The presented concept is a different approach and separates the friction system from the bulk Aluminum brake disc, achieved by coating of the friction rings. By locally reinforcing the friction rings, the good machinability and ductility of the base body is maintained and simultaneously the friction surface is sufficiently protected to resist the frictional loading during a brake application. In this work, fundamental studies on a brake dynamometer were conducted and supplemented by microstructural investigation to identify damage mechanisms and to judge the technical application of the concept.

Gulden, Florian, Gramstat, Sebastian, Stich, Anton, Hoppel, Heinz Werner, Tetzlaff, Ulrich

Cementitious-Based Brake Pads Technology: Performance, Low Energy Consumption, Emission Drop

2018-01-186710/5/2018

Brake pads employing innovative hydraulic inorganic binders in place of common state-of-the-art thermosetting phenolic resins have been produced by means of a unique prototypal equipment and a distinctive manufacturing process. The unicity of the process enables us to exclude completely any thermal cycle in the manufacturing steps, with a considerable positive energy balance compared to the standard counterpart. Realized brake pads have indeed been successfully tuned to meet the braking performances of phenolic counterparts. In the present work our latest efforts in this field are illustrated, focusing our attention to three main areas of interest: performance, energy consumption, volatile organic emissions. One selected exponent of our cementitious-based material is reported, demonstrating its capability of matching both standard OE and AM braking performances (investigated through a full scale brake dynamometer by SAE J2522 procedure), and its feasibility to be released as an actual AM material according to ECE R90 regulation (road test on vehicle). The energetic evaluation of the employed technology in term of prototypal manufacturing process and employed raw materials has been established, demonstrating the advantages of this new system compared to the standard one. Our investigation finally reports selected thermo-chemical analysis (TG-EGA and pyrolysis PY-GC/MS) devoted at identifying the key organic compounds potentially/eventually emitted during braking at various temperatures. Our material shows a dramatic drop of the volatile hazardous/organic compounds (VHCs/VOCs) released by a standard phenolic homologous, thus increasing the favorable characteristics of such inorganic hydraulic-binder brake pads and related technology.

Sanguineti, Alessandro, Samela, Alessandro, Rampinelli, Flavio, Bottalico, Luca, Ranza, Luigi, Romeo, Marco, Bonfanti, Andrea

Torsional Fluctuations Consideration while Design of Synchro Rings

2018-01-18239/10/2018

In today’s manual transmissions of car, gearshift system requires high performance with particular emphasis on low effort, minimal travel and positive feel. To meet these targets, a high capacity multi cone synchronizers along with higher co-efficient of friction material used for lower gears. The design of synchronizer with these specifications is influenced by torsional fluctuations from engine. Excessive torsional vibrations leads to wobbling of synchro rings within the peripheral clearances with surrounding parts. Wobbling leads to abrasion wear of frictional area of synchro ring causing grating or crashing noise of gears during shifting. This paper presents the optimization of the multiple cone synchronizer design exposed to excessive torsional vibrations and validation of the same on test bench during development stage instead vehicle level validation.

Tawhare, Nitin, Aswale, Dhananjay, Ponkshe, Makarand

Truck Brake Failure: Differences between Failure Modes for Drum and Disc Brakes

2018-01-05284/3/2018

On-highway heavy trucks are fitted with air disc brakes with increasing frequency. Disc brakes and traditional air drum brakes have different adjustment and heat dissipation characteristics. These differences lead to different failure modes when overheated. This paper describes how adjustment and other in-use factors affect the general braking capability of on-highway trucks fitted with disc and drum brakes. Simulations of a loaded tractor-trailer on a long, down-hill grade are used to predict brake temperature increase over time, and how that temperature increase can result in a runaway condition. The tractor and trailer are modeled with both traditional drum brakes and new disc brakes to illustrate operational differences between the two brake types.

Day, Terry D.

Test Procedures for Shear Strength of Automotive Brake Pads and Brake Lining Assemblies

J840_201711 (Current)11/15/2017

Brake Linings Standards Committee

Influences of Initial DTV on Thermomechnical Coupling in Disc Brake System

2017-01-24929/17/2017

In this paper, the initial disc thickness variation (DTV) of a ventilated disc in automotive brake system is modeled as sinusoidal function of the second order. The transient thermomechanical coupling properties of the brake system is simulated using finite element (FE) modeling. The system models and results were verified by a thermomechanical coupling test of a disc brake conducted on a brake dynamometer. By using varied evaluation indexes such as the temperature distribution, the normal stress and the elastic deformation of disc surfaces, the influences of the initial DTV and its direction as well as its amplitude on the thermomechanical coupling characteristics were analyzed. The simulation results show that the distribution of temperature and the normal stress in circumferential direction exhibit the same sinusoidal function of the second order as the modeled initial DTV property, which is different from the thermomechanical coupling characteristics caused by disc surface initial run-out (LRO). Whereas the thermomechnical coupling property of the disc in circumferential direction exhibit the same sinusoidal function of the second order as that of the initial DTV, the distribution of the temperature, the normal stress and the elastic deformation in radial direction are found to be uniform. The changes in the magnitude of initial DTV are found to have insignificant effects on the changes in the overall thermomechnical coupling property. However, the circumferential gradients of the temperature, the normal stress, and the maximum disc distortion increase linearly with the increase of the magnitude of the initial DTV. The radial gradients of these quantities are not linear proportional to the magnitude of the initial DTV.

Meng, Dejian, Wang, Ziyi, Zhang, Lijun, Yu, Zhuoping

Sizing Next Generation High Performance Brake Systems with Copper Free Linings

2017-01-25329/17/2017

The high performance brake systems of today are usually in a delicate balance - walking the fine line between being overpowered by some of the most potent powertrains, some of the grippiest tires, and some of the most demanding race tracks that the automotive world has ever seen - and saddling the vehicle with excess kilograms of unsprung mass with oversized brakes, forcing significant compromises in drivability with oversized tires and wheels. Brake system design for high performance vehicles has often relied on a very deep understanding of friction material performance (friction, wear, and compressibility) in race track conditions, with sufficient knowledge to enable this razor’s edge design. With significant restrictions in copper content of automotive brake linings becoming reality in California and Washington State in 2021, and a more or less complete phase-out of copper in linings occurring in 2024, one of the key ingredients of high performance linings - critical for heat transfer, high temperature tribofilms, and medium to high temperature friction - can no longer be used. This paper looks at dynamometer-based performance data from a new generation of copper-free high performance brake linings, and makes comparisons where appropriate to a current copper-containing lining. Following brake system sizing methodologies (some of which have been described in literature previously, and some of which are new and generate improved correlation to race track operation), the brake system of a case study high performance vehicle is reviewed for the impact that the copper free linings has on it. Data are generated using analysis tools, with correlation to vehicle test results. It will be shown that meeting the demands of race track usage with copper-free lining materials is possible, but that it will affect brake system design in some cases.

Antanaitis, David B., Shenberger, Michael, Votteler, Max

Development of Noise Propensity Index (NPI) for Robust Brake Friction

2017-01-25299/17/2017

A semi-empirical index to evaluate the noise propensity of brake friction materials is introduced. The noise propensity index (NPI) is based on the ratio of surface and matrix stiffness of the friction material, fraction of high-pressure contact plateaus on the sliding surface, and standard deviation of the surface stiffness of the friction material that affect the amplitude and frequency of the stick-slip oscillation. The correlation between noise occurrence and NPI was examined using various brake linings for commercial vehicles. The results obtained from reduced-scale noise dynamometer and vehicle tests indicated that NPI is well correlated with noise propensity. The analysis of the stick-slip profiles also indicated that the surface property affects the amplitude of friction oscillation, while the mechanical property of the friction material influences the propagation of friction oscillation after the onset of vibration. An additional case study for noise reduction was carried out using commercial brake friction materials before and after the modification of NPI. The results of the case study based on in-vehicle noise tests indicate that a robust friction material can be designed by reducing the stiffness ratio and large contact plateaus on the sliding surface of brake friction materials.

Cho, Jae Seol, Jeong, JongYun, Kim, Hyoung Woo, Lee, Hwa Sun, Park, Yang Woo, Lim, Junghwan, Kim, Yoonjae, Kim, Jinwoo, Joo, Byung Soo, Jang, Ho

In-Plane and Out-of-Plane Vibrations of Brake Linings on the Rotor

2017-01-25309/17/2017

The dynamics and, in particular, the NVH phenomena in brakes are still in the focus of research. Recent investigations of for example Rhee et al. show two principal vibrational forms of the linings on the rotor [1]. The first form is characterized by vibrations where both linings are in-phase (minimal differential torque between the inner pad and the outer pad). This produces in-plane vibrations of the rotor and results in high-frequency squealing events in the brake. The second form is an antiphase vibration of the brake linings with respect to each other (increased differential torque between the inner pad and the outer pad). This produce directly out-of-plane vibrational modes of the disc, which results in lower-frequency caliper and rotor oscillations. One hypothesis is that different wear densities of the linings essentially characterize the two vibrational modes. The wear behavior is not taken into consideration of this paper as it will be discussed in further publications. This paper deals with a low dimensional dynamical system and examines the vibrations, and analyzes essential influencing parameters on the different vibrational events.

Ostermeyer, Georg Peter, Otto, Johannes, Rhee, Seong Kwan

Proposal for an SAE Standard to Define, Dimension, and Measure Disc Brake Plates for Manufacture

2017-01-25049/17/2017

As the brake industry moves completely into globalization, a standardized method to define and validate the dimensions of backing plates, in a way that is both clear and feasible, is of critical importance for manufacturers at all tiers. The plate drawing not only defines the component as it fits into a brake assembly; it is also what the plate supplier relies on to define the plate for manufacture. If a drawing does not define every dimensional aspect of the product with perfect clarity, in ways that are easily measured, loss of time and resources will result from questions and/or mistakes. This paper proposes an SAE standard for defining the dimensional requirements of backing plates on the drawings themselves, and defining the measuring procedures used to validate those dimensions. The proposed standard employs already established methods such as geometric dimensioning and tolerancing (GD&T), including instruction on its proper application to features specific to backing plates. Current ‘best practices’ of design and drafting in our industry are similarly highlighted; drawing clarity, revision control, and dimensioning for both function and manufacturability. Generic examples are used to illustrate both the advantages of best drafting practices, and the potential failure modes that can result from poor drafting practices. The standard also proposes the best methods of measurement required to properly validate requirements such as feature size and location, surface roughness, plate flatness and bow shape. Most importantly; this paper invites the industry professionals responsible for both creating and using backing plate drawings, to join or collaborate with the SAE Brake Linings Standards Committee and help grow this paper from a proposal to a globally accepted engineering standard.

Lambert, Scott

The Effect of Commercial Vehicle Head-Up Display Reminding System on Driving Safety in Mountainous Area

2017-01-25009/17/2017

Head-up Display (HUD) system can avoid drivers’ distraction on dashboard and effectively reduce collisions caused by emergency events, which is gradually being realized by researchers around the world. However, the current HUD only displays information like speed, fuel consumption, other information like acceleration and braking can’t be displayed yet. This research will use the indicator symbol‘s color and position change to remind drivers to brake or accelerate. Drivers can do driving operation timely and accurately. The system has the advantages of safety, intuition and real-time. The vehicle safe speed is calculated according to the road parameters, like adhesion coefficient and slope, and vehicle parameters, such as vehicle mass and centroid. Then, the appropriate braking operations are obtained by combining the vehicle driving state. The braking information is corresponded to the color and position change of the indicator symbol to prompt the drivers by the HUD interface. At the same time, under different driving conditions, experiments will be carried out to find out the difference of driver’s braking operations when there is braking information presentation or there is not. The effects of different braking operations on driving safety performance will be evaluated. Compared with the condition of no braking information presentation, braking information presentation can make the start braking time ahead of schedule. In addition, the emergency braking situation will be reduced appropriately. The results show that the braking information presentation based on the HUD system has significant effects on improving driving safety.

Huang, Bo, Xia, Wanyang, Tan, Gangfeng, Xiao, Longjie, Wang, Zongsong

Experimental Study of Howl Noise Phenomenon Related to Drum Brake Squeal

2017-36-00075/24/2017

The improvement of motor’s power requires consequently the improvement in brake system also. The kinetic energy of moving vehicles is transformed in a big part of heat, but there is a part that can be transformed in vibration and sound pressure. One of these vibration and sound pressure complain is known as howl noise. The howl noise complain is very intense and uncomfortable for passengers and pedestrians. Today, the customers spend a lot of money in his vehicles comfort and this disorder can’t occur. This paper presents a methodology which uses Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA) to survey the dynamic behavior of suspension and brake systems at the howl noise occurrence condition.

Guimarães, Luiz Roberto, Abreu, Robson Demétrius Araújo, Carvalho, Ademir, Ferreto, Claudio Jr.

Specific Gravity of Friction Material

J380_201702 (Current)2/2/2017

Specific gravity is a nondestructive test used as a quality control check of the consistency of formulation and processing of brake lining. The specific gravity and the range of specific gravity are peculiar to each formulation and, therefore, the acceptable values or range must be established for each formulation by the manufacturer. Specific gravity alone shows nothing about a materials in use performance. The specific gravity of sintered metal powder friction materials, particularly those which have steel backing members, is usually determined somewhat differently. Reference ASTM B 376.

Brake Linings Standards Committee

Gogan Hardness of Brake Lining

J379_201702 (Current)2/2/2017

Hardness measurements are used as a quality control check of the consistency of formulation and processing of brake linings. Gogan hardness is nondestructive (the penetrator causes shallow surface deformation.). Gogan hardness method alone does not show anything about a lining’s ability to develop friction or to resist fade when used as a friction element in brakes. The hardness and the range of hardness are peculiar to each formulation, thickness, and contour; therefore, the acceptable values and ranges must be established for each formulation and part configuration by the manufacturer.

Brake Linings Standards Committee

Experimental Study of Bus Noise Phenomenon in a Suspension System Assembled with Drum Brakes Through Modal Analysis Techniques

2016-36-018910/25/2016

The automotive industry currently has a big concern with the vibro-acoustic comfort. The growth of concurrence and the clients requirement becomes necessary the researches in new techniques for analysis and improvement. Hence many vibro-acoustic phenomena causes uncomfortable noises in a vehicle. One of this noises is descendant of braking system and is known as Bus Noise. This paper presents a methodology which uses Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA) to survey the dynamic behavior of suspension and brake systems at the Bus Noise occurrence condition.

Guimarães, Luiz Roberto, Abreu, Robson Demétrius Araújo, Ferreto, Claudio Junior

Alkali-Activated Inorganic Based Brake Pads: Realization and Performances of Alternative Friction Materials for a Concrete Industrial Application

2016-01-19139/18/2016

Organic brake pads for automotive can be defined as brake linings with bonding matrix constituted of high-temperature thermosetting resins. Bonded together inside the polymeric binder are a mix of components (e.g. abrasives, lubricants, reinforcements, fillers, modifiers…), each playing a distinctive role in determining the tribology and friction activity of the final friction material. The herein reported work presents inorganic “alkali-activated”-based materials suitable for the production of alternative brake linings (i.e. brake pads), by means of an unconventional low-temperature wet process. Exploiting the hydraulic activity of specific components when exposed to an alkaline environment, such peculiar inorganic materials are capable of coming to a complete hardening without the need of traditional high-temperature energivorous procedures. The main advantages of these materials resides in: the decreased embodied energy of the employed raw materials, the reduction of process costs, a potential drop of the emitted pollutants coming from the high-temperature degradation of organic resins. In the present work the results of our investigation in the field are illustrated, our prototype inorganic material is indeed compared to the original resin-based OE and to another traditional phenolic alternative. Brake pads were tested on a full-scale automotive brake dynamometer, following SAE J2522 (AK Master) procedure. In order to prove the excellent performance of such inorganic materials even under high-demanding conditions, brake pads were also tested by means of an internal fading procedure. The results obtained so far are promising and pave the way to further developments toward a concrete industrialization of these unconventional class of friction materials.

Sanguineti, Alessandro, Tosi, Federico, Bonfanti, Andrea, Rampinelli, Flavio

Service Maintenance of SAE J1703 and J1704 Brake Fluids in Motor Vehicle Brake Systems

J1707_201609 (Historical)

9/13/2016

Brake Fluids Standards Committee

Measurement of Disc Brake Friction Material Underlayer Distribution

J2724_201605 (Current)5/24/2016

This procedure describes a method for measuring the fraction of underlayer (also referred to as backing layer) existing at any given height above the a disc brake friction materials shoe plate. Measuring underlayer distribution is useful for computing useable lining thickness and for friction material quality management.

Brake Linings Standards Committee

Influences of Pad Backplate on Thermo-Mechnical Coupling in Disc Brake

2016-01-13544/5/2016

The transient thermo-mechanical coupling dynamic model of ventilated disc brake with asymmetrical outer and inner thickness was established by means of Msc-marc software. In the model, pad backplate is simplified as a rigid surface with the same shape of brake lining and is bonded together with brake lining. Control node is associated with the rigid surface and the equivalent force that replaces the pressure is applied on the control nodes, of which the degrees of freedom in radial and rotational directions are constrained. With distribution characteristics of disc temperature field, normal stress field and lateral thermo-elastic deformation and thickness for the evaluation, the impacts of brake pad constraints on brake thermomechanical coupling characteristics were analyzed. The simulation results show that the brake pad back plate is an important structure in brake thermo-mechanical coupling analysis, which can’t be ignored in simulation computing. The brake pad constraints can affect thermo-mechanical coupling characteristics of disc brake directly.

Meng, Dejian, Zhang, Lijun, Yu, Zhuoping

Controlling Backlash in Mammography Systems

TBMG-239272/1/2016

Medical imaging equipment, water handling systems, conveyors, robotic systems, and rotary and linear actuators are among the many devices that may be fitted with electric friction brakes to hold their loads in place when the power is off or disrupted.

Performance of Low-metallic Cu-free Brake Pads with Two Different Graphite Types

2015-01-26779/27/2015

Automotive brake lining materials are complex composites consisting of numerous ingredients allowing for their optimal performance. Since regulations are increasingly limiting Cu content in brake pads and Cu exhibits extremely high thermal conductivity, graphites being excellent heat conducting materials themselves, are often considered for use as potential Cu replacement. This paper surveys the role of two types of carbons (Superior Graphite) with high thermal conductivity but different mechanical properties and morphology: the so-called i) purified flake graphite (PFG) and the ii) resilient graphitic carbon (RGC). A successful “high-end” commercial low-metallic brake pad was re-formulated (SIU Carbondale) by removing of over 20 wt. % of Cu and replacing it with a cocktail of ingredients including 15 wt. % of these two graphite types (RGC and PFG). Original equipment manufacturer (OEM) Crown Victoria 1999 mold was used to prepare the pads and they were subjected to the SAE J2430 test and BEEP evaluation using the full-scale automotive brake dynamometer (Link Engineering M 2800) and original hardware (rotor and caliper). After friction tests, the surfaces of pads were explored using scanning electron microscopy equipped with the energy dispersive X-ray microanalysis (FEG450 and Inca System) and X-ray diffraction (Rigaku Max-Flash-B). The performance of two different low-metallic pads was different. Both formulations exhibited extremely good stability of friction during fade section. The different friction levels and different wear of samples were related to the specific surfaces developed on two different pads containing RGC and PFG graphites and encountering rotors were covered by a discontinuous (patchy) friction layer. The capacity of the PFG to reduce surface oxides is considerably higher when compared to the RGC. Proper understanding of role of individual graphitic forms in particular formulations can be very beneficial when optimizing the performance of brake pads.

Daei, Amir Reza, Majumdar, Diptarka, Filip, Peter

Influence of the Automotive Brake Wear Debris on the Environment - A Review of Recent Research

2015-01-26639/27/2015

Automotive brake linings are complex composite materials. Some raw materials used by manufacturers or the compounds created during the friction process might be potentially hazardous and may cause various adverse effects. Different fractions of the brake wear debris can be released during braking: i) the airborne and ii) the nonairborne. Due to the small size and minimum gravitational action, the airborne particles could be spread for long distances from a source and typically remain suspended in the air for long periods of time. Our previous research demonstrated that the airborne fraction contains considerable amounts of different nanoparticulates. On the other hand, the emitted nonairborne fraction typically settles on vehicle/brake hardware surfaces and in the vicinity of roads. The nonairborne particles are considered to be relatively large, but it was shown that nano-sized particles readily attach to them and can be released later. This study is focused on the recent research in the field of brake wear debris detection in the environment (road dust, soil and sediments, water runoffs, air pollution) as well as on the possible impact on plants, animals and human health. The review of recently published papers allowed for the summary of the spectrum of relevant experimental techniques used currently for identification and analysis of brake wear debris, and for the most recent opinions on their impact on the environment and health. It is suggested that consideration of the environmental aspects becomes the necessary aspect of brake/friction materials design.

Peikertova, Pavlina, Filip, Peter

Optimization of Brake Friction Materials Using Mathematical Methods and Testing

2015-01-26619/27/2015

Brake linings have complex microstructure and consist of different components. Fast growing automotive industry requires new brake lining materials to be developed at considerably shorter time periods. The purpose of this research was to generate the knowledge for optimizing of brake friction materials formula with mathematical methods which can result in minimizing the number of experiments/test, saving development time and costs with optimal friction performance of brakes. A combination of processing methods, raw materials and testing supported with the Artificial Neural Network (ANN) and Taguchi design of experiment (DOE) allowed achieving excellent results in a very short time period. Friction performance and wear data from a series of Friction Assessment and Screening Test (FAST) were used to train an artificial neural network, which was used to optimize the formulations. The averaged COF, COF variation and wear were used as the output parameters. Weight percentage of raw materials denoted as an input parameter and these data were used to train ANN. A two layer feedforward ANN with back propagation was used in this study. Back propagation learning algorithm can be divided into two phases: i) propagation and ii) weight update. The friction performance of the optimized friction materials was considerably better when compared to the baseline commercial brake lining materials. This method can be applied to development of any type of complex friction materials.

Daei, Amir Reza, Davoudzadeh, Nima, Filip, Peter

Identification of Organic Compounds Released from Low-Metallic Automotive Model Brake Pad and its Non-Airborne Wear Particles

2015-01-26629/27/2015

The brake wear contribution to the environmental pollution has been extensively discussed, with major focus on asbestos and heavy metals released to the environment. Only limited attention was paid to released organic compounds generated during friction processes, although the organic and carbonaceous components are not the minor part in brake lining formulations. Friction processes in brakes are associated with relatively high temperatures and high pressures on the friction surfaces which relates to the thermal decomposition of the organic components in friction materials and to brake lining thermal fade. Thus, this study focuses on the identification of organic compounds released from a model low metallic brake material. Several methods were used for the analysis: GC/MS screening of brake pad samples, brake wear debris and carbonaceous raw materials used in formulations of model pads; GC/MS screening of brake pad samples pyrolyzed at 300, 750, and 1000°C, respectively, and FTIR analysis of brake pads and their wear debris. Higher quantity of organic compounds was identified in extract of the milled brake pad composite compared to the wear debris. More than 80 organic compounds were identified to be potentially released during braking. The major constituents were phenols, aliphatic and aromatic hydrocarbons, and their derivatives. Some of the identified compounds are known to have adverse effects even with mutagenic and carcinogenic potency to humans.

Plachá, Daniela, Peikertova, Pavlina, Kukutschova, Jana, Lee, Poh Wah, Čabanová, Kristina, Karas, Jiří, Kuchařová, Jana, Filip, Peter

Methods for Sizing Brake Pads for High Performance Brakes

2015-01-26799/27/2015

An aspect of high performance brake design that has remained strikingly empirical is that of determining the correct sizing of the brake pad - in terms of both area and volume - to match well with a high performance vehicle application. Too small of a pad risks issues with fade and wear life on the track, and too large has significant penalties in cost, mass, and packaging space of the caliper, along with difficulties in maintaining adequate caliper stiffness and its impact on pedal feel and response time. As most who have spent time around high performance brakes can attest to, there methods for determining minimum brake pad area, usually related in some form or another to the peak power the brake must absorb (functions of vehicle mass and top speed are common). However, the basis for these metrics are often lost (or closely guarded), and provide very little guidance for the effects of the final design (pad area) deviating from the recommended value. This paper proposes methods, justified with dynamometer and vehicle test data, to determine brake pad area (based on considerations for fade performance), and brake pad volume (based on considerations for wear life), for high performance brake systems designed for high speed, closed loop race track operation. The methodologies are geared towards “high performance street” friction materials.

Antanaitis, David B.

Hardness of Brake Lining

J2654_201508 (Current)

8/27/2015

Hardness measurements are used as a quality control check of the consistency of formulation and processing of brake linings. This hardness method is nondestructive. NOTE—This method is not a measure of friction level. The hardness and the range of hardness are characteristic of each formulation; therefore, the acceptable values and ranges must be established for each formulation and may be affected by processing. NOTE—The hardness of sintered powder metal lining is usually determined with Rockwell superficial hardness equipment. (See ASTM B 347)

Brake Linings Standards Committee