Browse Topic: Brake lines

Items (90)

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

Automotive Air Brake Line Couplers (Gladhands)

J318_202106 (Current)

6/10/2021

This SAE Recommended Practice is intended to provide design, interchangeable dimensions, testing procedures, performance requirements, and minimum identification for gladhand-type air line couplers used to connect the brake systems of trucks, truck-tractors, trailers, and dollies when these vehicles are joined to operate as a combination unit.

Truck and Bus Brake Supply and Control Components Committee

Research on Compensation Redundancy Control for Basic Force Boosting Failure of Electro-Booster Brake System

2020-01-02164/14/2020

As a new brake-by-wire solution, the electro-booster (Ebooster) brake system can work with the electronic stability program (ESP) equipped in the real vehicle to realize various excellent functions such as basic force boosting (BFB), active braking and energy recovery, which is promoting the development of smart vehicles. Among them, the BFB is the function of Ebooster's servo force to assist the driver's brake pedal force establishing high-intensity braking pressure. After the BFB function failure of the Ebooster, it was not possible to provide sufficient brake pressure for the driver's normal braking, and eventually led to traffic accidents. In this paper, a compensation redundancy control strategy based on ESP is proposed for the BFB failure of the self-designed Ebooster. Firstly, introduced the working principle of Ebooster and ESP, and a suitable pressure-building circuit was selected for the dual brake actuator system; Secondly, after the BFB failure of Ebooster, the rule-based strategy of braking awareness recognition was designed. Thirdly, a layered closed-loop compensation control strategy is designed based on the ESP to restore the pressure building capacity of the hydraulic system. Finally, based on dSPACE products, a hardware-in-the-loop (HiL) experimental bench with dual brake actuators including ESP and Ebooster was built for algorithm verification. The HiL experiment results show that after the BFB failure of Ebooster, the designed compensation redundancy control algorithm can restore the Pressure-Volume (P-V) characteristics of the brake system just like Ebooster's conventional BFB mode, and improve vehicle driving safety.

Zhao, Jian, Chen, Zhicheng, Zhu, Bing, Wu, Jian

Automotive Air Brake Line Couplers (Gladhands)

J318_201911 (Historical)11/20/2019

Truck and Bus Brake Supply and Control Components 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

Design Optimization of the Disc Brake for Squeal Noise Reduction

2018-01-187410/5/2018

In this paper, squeal noise reduction method of the disc brake was proposed. And, its effectiveness was described. Pad motion was studied with pad abutment types comparison. The brake design was optimized by using the design of experiment method. The effectiveness of the optimum design was clarified by the noise tests with a dynamometer.

Park, Jintack

Automotive Vehicle Brake Squeal Test Recommend Practice

J2625_201707 (Current)7/24/2017

This procedure is applicable to squeal type noise occurrences for passenger car and light truck type vehicles that are used under conventional operating conditions. For the purposes of this test procedure, squeal is defined as occurring between 900 and 18 000 Hz.

Brake NVH Standards Committee

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

J1707_201609 (Historical)

9/13/2016

Brake Fluids 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.

Characterization of Disc Wear Particles Transferred to the NAO Pad Surface: Brake Squeal

2015-01-26849/27/2015

Rear disc brake squeal test results confirm the disc wear - brake squeal correlation reported earlier on front disc brakes. A significant amount of Fe transferred from the disc to the NAO pad surface is detected and the distribution of the transferred Fe is very non-uniform on the pad surface. The pad surface formulation reaches that of Low-Steel Lomets. Disc pads from a noisier brake retain more transferred particles than from a less noisy brake. The pad surface retains more transferred Fe after noise test procedures than after performance test procedures. The transferred Fe particles are either barely visible or invisible. During brake noise test procedures, discs wear in weight as much as disc pads. No correlation is found between average in-stop Mu, maximum in-stop Mu or in-stop delta Mu and brake squeal.

Lee, Seongjoo, Kim, ShinWook, Kim, ShinWan, Rhee, Seong

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

Investigation and Reduction of Brake Squeal and Groan Noise

2015-01-26879/27/2015

Brake noise is one of the common complaints and an irritant not just for the vehicle occupants but equally for the passers-by. Brake noise is actually vibration that is occurring at a frequency that is audible to the human ear. This occurrence of brake noise like brake squeal (>1 kHz) and groan (<1 kHz) is often very intense and can lead to vehicle complaints. During a brake noise event, vehicle basic structure and suspension system components are excited due to brake system vibration and result in a resonance that is perceived in the form of a noise. Proposed work discusses an experimental study that is carried out on a vehicle for addressing concern regarding disc brake squeal and groan noise. Based on the preliminary inputs, vehicle level study was carried out in order to simulate the problem and objectively capture its severity. During the process major influencing factors like hydraulic brake pressure, vehicle speed, brake temperature etc. have been monitored and varied across different levels in order to cover the complete operating range and for establishing a better understanding of the environment in which the noise event occurs. Subsequently, different options were tried out in order to optimize the sound pressure levels inside and outside the passenger cabin without compromising on the overall braking effectiveness of the vehicle. Finally, a comparative analysis is carried out for selecting the best option for implementation on vehicle.

Choudhary, Aditya Kant, Mense, Yogesh, Singh, Saurabh, Shridhare, Mahesh

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

On the Coupling Stiffness in Closed-Loop Coupling Disc Brake Model through Optimization

2015-01-06684/14/2015

The study and prevention of unstable vibration is a challenging task for vehicle industry. Improving predicting accuracy of braking squeal model is of great concern. Closed-loop coupling disc brake model is widely used in complex eigenvalue analysis and further analysis. The coupling stiffness of disc rotor and pads is one of the most important parameters in the model. But in most studies the stiffness is calculated by simple static force-deformation simulation. In this paper, a closed-loop coupling disc brake model is built. Initial values of coupling stiffness are estimated from static calculation. Experiment modal analysis of stationary disc brake system with brake line pressure and brake torques applied is conducted. Then an optimization process is initiated to minimize the differences between modal frequencies predicted by the stationary model and those from test. Thus model parameters more close to reality are found. Unstable mode prediction results using parameters before / after optimization are compared with those from brake noise bench test. The results after parameter optimization are in good correlation with test result and illustrate obvious improvement of predicting accuracy. Finally, the presented method is used to study the relationship between the coupling stiffness and brake conditions, i.e. brake-line pressure. The result shows accordant with literature.

Du, Yongchang, Gao, Pu, Wang, Yujian, Lv, Yingping

ASURT Formula Student Brake Design

2014-01-24879/28/2014

The Braking System is the most crucial part of the racing vehicle. There is no doubt, that if only one minority failure in the braking system took place, this would be more than enough reason to cause the racing team disqualification from the competition. Time is the main and the most important criteria for any racing competition; on the other hand the formula student “FS UK SAE” competition care the most about developing the automotive engineering sense in the students by putting them under strict rules normally taken from the original version “formula 1” to encourage their creativity to reach the optimum performance under these strict rules. One of the most important rules is “No Braking by wire”, and the obvious consequences are more stopping distance and time. Braking distance is a critical facture in achieving racing success in a competitive domain. This report will cover using the bias bar, dynamic weight distribution “before and after braking” and carefully choosing the braking and suspension system components dimensions, in order to fulfill the main functions of “ABS and EBD” which are preventing the wheels from lock-up and preventing side skid of the vehicle during cornering in the different dynamic tests with full consideration of the maximum approachable deceleration of the vehicle without locking up without using any kind of electronic “actuators or control”. Mathematical model “Matlab” and Physical model “AME SIM” will be used to support the report's results.

Barakat, Mohamed Samy

Combined Testing Technique: Development of Friction Brake System for Electric Vehicle

2014-01-25299/28/2014

The presented research discusses the experimental procedure developed for testing of friction brake systems installed on the modern electric vehicles. Approach of combined experimental technique utilizing hardware-in-the-loop platform and brake dynamometer is introduced. As the case study, an influence of brake lining coefficient of friction fluctuations on the anti-lock brake system (ABS) performance is investigated. The ABS algorithm is represented by the direct slip control aimed to the precise tracking of reference slip ratio by means of electric and friction brake system. Vehicle prototype is represented by RWD electric vehicle with in-wheel motors. Results, representing the investigated phenomenon, are derived using the developed combined test bench. The achieved results give a basis for further extension of standard brake testing procedures.

Augsburg, Klaus, Savitski, Dzmitry, Heidrich, Lukas, Ivanov, Valentin

Mountain Braking Test Venue Study

2014-01-25269/28/2014

Assessment of braking performance that includes brake fade is a critical part of the evaluation of military light tactical vehicles as it is for conventional light cars and trucks. These vehicles are sometimes called upon to operate in severe mountain regions that challenge the braking performance well beyond the environment in which these vehicles are normally operated. The U.S. Army Test Operating Procedure (TOP) 2-2-608 includes a test schedule conducted in the mountainous region near Jennerstown, Pennsylvania. While this test procedure represents a typical mountain environment, it does not represent the most severe mountain descents that can be encountered across the United States. As a preliminary step to developing a representative severe mountain descent braking test, mountain roads throughout the United States were evaluated analytically to identify potential test venues. A literature search was first undertaken to identify test procedures and test sites that were utilized by automobile manufacturers, independent automotive testing companies, U.S. Army Aberdeen Test Center (ATC), and the University of Michigan Transportation Research Institute (UMTRI). Potential mountain road venues documented by R&R Publishing were examined for severity by estimating the brake lining temperatures resulting from the length and grade of the road, and the speed limit by using a fundamental analysis documented by UMTRI. Several candidate mountain roads for evaluation were recommended based upon estimated brake lining temperature and safety considerations. In addition, several automotive standards and Government test procedures were simulated and their brake temperature severity compared. Disclaimer: Reference herein to any specific commercial company, product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the Department of the Army (DoA). The opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or the DoA, and shall not be used for advertising or product endorsement purposes.

Norman, Kenneth D., Singh, Amandeep

Development of Composite Brake Pedal Stroke Simulator for Electro-Hydraulic Braking System

2014-01-01174/1/2014

A brake pedal stroke simulator for Electro-hydraulic Braking System (EHBS) was developed to ensure the comfort braking pedal feel for the brake-by-wire system. An EHBS with an integrated master cylinder was proposed, and a composite brake pedal stroke simulator was designed for the EHBS, which was comprised of two inline springs and a third parallel one. A normally closed solenoid valve was used to connect the master cylinder booster chamber and the stroke simulator. The suitable brake pedal stroke was achieved by three stages of these springs' compression, whereas the solenoid valve was shutdown to enable mechanical control of the service brakes when electrical faults appeared. The pedal stroke simulator and the EHBS were modeled in MATLAB/SIMULINK-AMESim, and then the pedal stroke characteristic including the depressing and releasing process and its influencing factors, namely the preload force of the return spring, the cross-sectional area of the solenoid valve orifice, piston damping coefficient, and the pressure booster ratio were analyzed during the normal and failsafe mode. A bench test and hardware-in-the-loop (HIL) simulation were built to verify the stroke simulator performance. The simulation and test results show that the proposed pedal stroke simulator can meet the requirements of EHBS with improved braking comfort and driving safety.

Liu, Yang, Sun, Zechang, JI, Wenbin

A Downhill Brake Strategy Focusing on Temperature and Wear Loss Control of Brake Systems

2013-01-23729/24/2013

Aiming at achieving the economy and safety of downhill brake process (running downward along a long slope at a constant velocity) of commercial vehicles, an integrated control strategy of the main brake system and auxiliary brake systems is proposed. Based on Electronic Controlled Braking System (EBS), the strategy distributes braking force to each brake system and each axle according to the thermodynamic feature of them and the wear loss of each brake lining, in order to achieve economy at the premise of safety. A simulation is conducted based on MATLAB/Simulink and TruckSim. Simulation results show that the strategy proposed could control the temperature of each brake system at a rational value, and the balanced wear loss of brake linings is facilitated, thus, the safety and economy of downhill brake is ensured.

Liu, Zongyu, Zheng, Hongyu, Xu, Wenkai, Yu, Zeyang

Automotive Air Brake Line Couplers (Gladhands)

J318_201305 (Historical)

5/28/2013

Truck and Bus Brake Supply and Control Components Committee

Connection and Accessory Locations for Towing Multiple Trailers - Truck and Bus

J849_201301 (Current)1/4/2013

Truck and Bus Brake Supply and Control Components Committee

Thermal Effects in Friction Materials - A Comprehensive Strategy for Modeling and Simulation

2012-01-17939/17/2012

Shorter product cycles, a high awareness for comfort properties on the customer side and an increasingly strict legislation with respect to environmental issues make the development of friction materials more and more challenging. In contrast to many other engineering tasks, nearly no software tools are available to the material developer, which systematically support the development process with simulations. This work focuses on the time-dependent three-dimensional heat distribution inside a pad material and shows, how heterogeneous material mixtures can be modeled, such that a prediction of non-stationary temperature fields becomes possible. In this context, a strategy is suggested, how the thermal interaction between pad and disk and the aspects of energy dissipation and heat partitioning can be described appropriately. The outcome is a simulation system that not only returns local temperature values for arbitrary boundary conditions, but which also makes a prediction of heat-induced physical and chemical phenomena possible, as they occur inside the material. Different case studies show how e.g. the oxidation of certain components or the degassing of the organic binder can be described. These concepts allow the material developer to systematically and virtually compare material variants in the early stage of a development process and to reduce the need for extensive prototyping and testing.

Bode, Kai, Ostermeyer, Georg-Peter

Automotive Air Brake Line Couplers (Gladhands)

J318_201206 (Historical)6/11/2012

Truck and Bus Brake Supply and Control Components Committee

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

J1707_201111 (Historical)

11/21/2011

Brake Fluids Standards Committee

How Do Nonlinearities Influence Brake Squeal?

2011-01-23659/18/2011

Brake squeal is usually investigated using linearized models and the eigenvalues of the linear equations of motion. Eigenvalues with positive real parts are interpreted as the onset of squeal. Nonlinearities are commonly neglected due to the high effort associated with the corresponding calculations. Following the linear theory, the vibration amplitude should increase exponentially. On the other hand experimental results and overall experience show, that brake squeal is a stationary or quasi-stationary vibration phenomenon with approximately constant amplitude. This can only be explained by introducing nonlinearities into the model. These nonlinearities are limiting the increasing vibration amplitudes to a stationary limit cycle. Considering experimentally identified material properties of the brake lining as the main source of nonlinearities in the system a nonlinear disk brake model is introduced. Using the eigenvalues and eigenvectors of the linearized system, the bifurcation of the nonlinear system is investigated by normal form theory. This complements the stability boundary obtained from an analysis of the linearized system. It is shown that the linear model can result in incorrect stability boundaries even with perfectly identified parameters. On the other hand, the nonlinear model predicts stability boundaries that are consistent with experimental results.

Hochlenert, Daniel, Von Wagner, Utz

The Effect of Metal Pickup to the Friction Interfaces

2011-01-23489/18/2011

Metal pickup is a phenomenon that can be observed during dynamic braking with automotive disc brakes. Hard metallic particle agglomerations embedded in the friction materials rubbing surface can lead to severe disc scoring, accelerated wear and deterioration of the friction surface of either brake disc or brake pad. Such kind of surface conditions are also suspected for generating brake squeal, even if a direct root cause effect had not been proven so far. Disc scoring effects have been reported for all kinds of applications, reaching from small passenger cars up to commercial vehicles as well as railroad brakes. Although such phenomena are known since long, they still appear causing problems in brake systems of today. Some recent papers have described the effect and mentioned preferable conditions for the appearance of metal pickup. Specific procedures have been proposed for provocation of the effect to allow a better and more systematic investigation of the influencing parameters. Observations on results of such experiments were described and several working hypotheses put forward with influences going back to the brake rotors metallurgy and surface finish as well as to the friction materials ingredients. This paper gives an overview to the actual situation of the research and developments about the effect of metal pickup generation. An investigation of a multitude of MPU cases from real car driving is used to cluster and structure the principal phenomena and discuss the various aspects. The discussion of the experimental results and the previous findings, lead to a new experimental set up which is proposed for further investigation and future works. This shall lead to a better way of investigating and understanding the influencing parameters within the brake system, rotor and brake lining for their effect to the phenomena.

Lange, Jürgen, Ostermeyer, Georg

Experimental Identification of Brake Lining Material Properties Subjected to Combined Static and High Frequency Loading - A Step Towards a Better Prediction of Disc Brake Squeal?

2011-01-23539/18/2011

Brake lining material is one of the main factors influencing brake squeal. Actual simulation of brake squeal suffers on the missing of correct material parameters identified under conditions relevant for squeal. The comparison of different measurement methods for friction material characterization, e.g. compressibility tests, modal analyses or ultrasonic measurements shows that the material properties strongly vary depending on the testing conditions which are static preload, dynamic amplitude, frequency range and the loading direction. The different results obtained from these various test procedures show a nonlinear and transversely isotropic material behavior of the brake lining. In order to identify the correct material parameters for successful brake squeal simulation it is necessary to reproduce the operating conditions during the squealing state as close as possible in experimental setups. The present paper introduces a measurement technique and an identification procedure for brake lining material properties in the out-of-plane direction reproducing the load parameters typical for brake squeal. These are preloaded configurations corresponding to squeal typical brake pressures and sinusoidal dynamic loading producing displacements in the micrometer range with frequencies in kHz-range corresponding to the noise emitting oscillations. Furthermore the identified linear and nonlinear brake lining material properties are presented and discussed.

Hornig, Sylwia Agnes, Von Wagner, Utz

Hot Judder - An Investigation of the Thermo-Elastic and Thermo-Plastic Effects during Braking

2011-01-15755/17/2011

Thermo-elastic and thermo-plastic behaviour takes place with a disc brake during heavy braking and it is this aspect of braking that this paper considers. The work is concerned with working towards developing design advice that provides uniform heating of the disc, and equally important, even dissipation of heat from the disc blade. The material presented emanates from a combination of modeling, on-vehicle testing but mainly laboratory observations and subsequent investigations. The experimental work makes use of a purpose built high speed brake dynamometer which incorporates the full vehicle suspension for controlled simulation of the brake and vehicle operating conditions. Advanced instrumentation allows dynamic measurement of brake pressure fluctuations, disc surface temperature and discrete vibration measurements. Disc run-out measurements using non-contacting displacement transducers show the disc taking up varying orders of deformation ranging from first to third order during high speed testing. This surface interrogation during braking identifies disc deformation including disc warping, “ripple” and the effects of “hot spotting”. The mechanical measurements are complemented by thermal imaging of the brake, these images showing the vane and vent patterns on the surface of the disc. The results also include static surface scanning, or topographical analysis, of the disc which is carried out at appropriate stages during testing. The work includes stress relieving of finished discs and subsequent dynamometer testing. This identifies that in-service stress relieving, due to high heat input during braking, is a strong possibility for the cause of disc “warping”. It is also seen that an elastic wave is established during a braking event, the disc returning to its original form on release of the brake.

Fieldhouse, John David, Bryant, David, Talbot, Chris John

Tire Chain Clearance - Trucks, Buses (Except Suburban, Intercity, and Transit Buses), and Combinations of Vehicles

J683_201105 (Current)

5/17/2011

The purpose of this SAE Information Report is to set up a guide as to body, frame, and wheel housing clearance to accommodate tire chains, and also the minimum bogie spacing to permit using chains on both axles. These dimensions apply to trucks, buses, and combinations of vehicles 10 001 lb (4535.06 kg) GVW and over, and are based upon recommendations of the Tire and Rim Association and of the National Association of Chain Manufacturers. The diagram shows clearance for chains over the tire ONLY and allowance must be made for spring deflections in determining fender clearance. See Figure 1 and Table 1.

Truck and Bus Total Vehicle Steering Committee