Browse Topic: Brake linings
This recommended practice covers the attachment of bonded anti-noise brake pad shims only. Mechanically attached shims (those without bonding) are not covered by this procedure.
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.
During validation of a new brake lining on a light duty truck application, the brake rotor exhibited high lateral runout on the friction surfaces. As the engineering team investigated the issue more carefully, they noticed the rotor lateral runout was also changing from revolution to revolution. The team ran testing on multiple light pickup vehicles and found differences in the amount of rotor runout variation. The rotor lateral runout and runout variation can cause vibration and pulsation of the passenger seat and the steering wheel. To identify the root cause of the high level of rotor lateral runout and runout variation, measurement data was collected and analyzed from the vehicle level test. During further analysis, some of the runout variation corresponded to a wheel bearing internal frequency. The bearing internal geometry was studied to confirm what factors affected the runout variation. The team also conducted testing to see how the mating components may have affected the wheel
This SAE Standard specifies a method for testing and measuring elastic constants in friction materials by precise ultrasonic velocity measurements. Measurement methods are also described for measurement of the out-of-plane modulus as a function of pre-load as well as the measurement of engineering constants as a function of temperature. Finally, methods are formulated to produce all engineering constants as a function of pre-load and temperature.
Test procedure for anti-lock brake system (ABS/anti-lock) performance for trucks, truck-tractors, and buses over 4536 kg (10000 pounds).
This SAE Recommended Practice (RP) establishes uniform powered vehicle-level test procedure for forward collision warning (FCW) and automatic emergency braking (AEB) used in trucks and buses greater than 10000 pounds (4535 kg) GVWR equipped with pneumatic brake systems for detecting, warning, and avoiding potential collisions. This RP does not apply to electric powered vehicles, trailers, dollies, etc., and does not intend to exclude any particular system or sensor technology. These FCW/AEB systems utilize various methodologies to identify, track, and communicate data/information to the operator and vehicle systems to warn, intervene, and/or mitigate in the momentary longitudinal control of the vehicle. This specification will test the functionality of the FCW/AEB (e.g., ability to detect objects in front of the vehicle), its ability to indicate FCW/AEB engagement and disengagement, the ability of the FCW/AEB to notify the human machine interface (HMI) or vehicle control system that an
This SAE Recommended Practice is intended for qualification testing for brake drums used on highway commercial vehicles with air brakes using an inertia-dynamometer procedure. This document consists of two distinct tests: Part A, durability and speed maintenance test, and Part B, heat check drag sequence test. Each test can be considered to be an independent evaluation of the brake drum which tests different properties.
This SAE Recommended Practice is intended for measuring the static brake torque performance of a pnuematically actuated brake assembly, friction material, and drum/disc combination on an inertia brake dynamometer.
The SAE J2521 procedure applies to high-frequency squeal noise occurrences for on-road passenger cars and light trucks below 4540 kg of GVWR. The procedure incorporates high-temperature and low-temperature test matrixes but does not fully account for the effects of the environment on brake squeal. For this test procedure, squeal occurs when the peak noise level is at least 70 dB(A) between 1.25 kHz and 16 kHz for tests using full suspension corners or full axle assemblies or between 2 kHz and 16 kHz for brakes not using a full suspension corner. Before using this recommended practice for chassis dynamometer testing, review in detail the specifics related to at least (a) instrumentation, including in-cabin microphones, (b) threshold levels for noise detection, (c) temperature control priority between the front and rear axles, (d) vehicle loading and load distribution, (e) cooling air and environmental conditioning, and (f) detailed nomenclature and labeling of channels and sensors.
This SAE Recommended Practice provides a field test procedure and instructions for air braked single unit trucks, buses, and combination vehicles. Brake force distribution field testing with systems post-reduce stopping distance changes is still appropriate, however, vehicles with electronically controlled braking systems are not covered in this document and may need to be addressed in the future. It also provides recommendations for: a Instrumentation and equipment. b Vehicle preparation. c Test of air-braked single and combination vehicles. d Calculation of brake force distribution. e This test procedure is intended to be used as a field procedure. If a more refined method, utilizing laboratory equipment, is required, refer to SAE J1505.
With the spread of new trends such as autonomous driving and vehicle subscription service, drivers may pay less attention to the maintenance of the vehicle. Brake pads being safety critical components, the wear condition of all service brakes is required by regulation to be indicated by either acoustic of optical devices or a means of visually checking the degree of brake lining wear [1]. Current application of the wear indicator in the market uses either sound generating metal strip or wire harness based pad wear sensor. The former is not effective in generating clear alarm to the driver, and the latter is not cost effective, and there is a need for more effective and low cost solution. In this paper, a pad wear monitoring system using MOC(Motor On Caliper) EPB(Electric Parking Brake) ECU is proposed. An MOC EPB is equipped with a motor, geartrain and an ECU. The motor current when applying the parking brake is influenced by the mechanical load at the brake pad side of the system. So
This SAE Recommend Practice specifies a method for measuring the deflection of friction materials and disc brake pad assemblies in a manner more consistent with classical material compressive strain testing. This SAE test method differs from SAE J2468 in the preload and maximum load applied to the test sample when deflection is measured. It adopts the material applied stress levels found in ISO 6310 (0.5 to 8.0 MPa) using a 25 mm diameter flat plunger.
In Brazil, 20% of the accidents involve commercial vehicles, the high load capacity and the big dimension of commercial vehicles, such bus and trucks, become this situation even more dangerous. To prevent crashes, robust parts and product validation methodologies are essential for a safer and cheaper transport. The drum brake is widely used in commercial transport, due to the cheaper cost of production. The disadvantage of the drum brake system it’s his low thermal dissipation, to decrease the vehicle velocity, the brake converts kinetic energy in thermal energy, causing loss of efficiency, degradation of material mechanical properties and life reduction, these thermal effects can be even more dangerous under extreme conditions, as overload, speeding, over adjustment (dragging), and bad system maintenance. Due the fact that the temperature affects significantly the vehicle performance, especially in drum brakes system, the friction pair is tested under the worst road scenarios
In order to have a detailed insight of a vehicle dynamics and performance of a car and its influencing parameters, it is common to use simulation programs to get this job done. The purpose of this work is to model the longitudinal dynamics of a Formula SAE prototype in Matlab/Simulink® environment, focusing on the braking dynamics and on the incorporation of collected data from the brake lining materials. The model was designed to receive data from a Formula SAE prototype, which are used in the interaction of subsystems, such as, brakes, sprung mass, aerodynamics and tires. The implementation of the three degrees of freedom for the sprung mass and the non-linear model used for the tires assure a better precision in the model. The brake bench tests were made in a machine that simulates the braking process and was defined as a Krauss testing procedure, which could be used to evaluate the coefficient of friction variation versus temperature. This data was implemented in the model, and
The aim of this paper was the proposal of a numerical procedure for the structural evaluation and durability validation of brake shoes, employing fatigue and finite element softwares that are able to predict the failure locations (and number of cycles to failure) with acceptable accuracy. The software Abaqus was used in the calculation of the stress and strain fields whereas the software fe-safe was employed in the evaluation of fatigue life. Accelerated tests were performed on a bench test that has been designed to match the operating conditions of the vehicles were the brake shoes are assembled. In those cases where only local plasticity is expected (rather than generalized plasticity) the procedure can somewhat be simplified by running linear elastic finite element analysis (instead of full non-linear), which is often called pseudo-elastic analysis [1]. Then the pseudo stresses and strains are corrected at post-processing time by means of the Neuber’s rule and Ramberg-Osgood
The static coefficient of friction between lining and shoe plays a fundamental role in the lining fixing project, which is the most important parameter for the riveted joint calculation. For the lining riveting, the rivet needs to ensure that friction material and shoe remain in contact through the normal force applied on the surfaces, but the rivet should not be exposed to shear forces. Thus, the brake torque transmission must occur through the static coefficient of friction between lining and shoe, not allowing relative slips or movements between the pair in contact. Therefore, the present study aims to understand the influence of the static friction coefficient between lining and shoe as a function of the lining internal superficial roughness, from the evaluation of different roughness conditions - contact area with shoe -. The static coefficient of friction between lining and shoe is a complex measurement to be performed, due to the cylindrical geometry of the drum brake system, so
This SAE Recommended Practice establishes a method of testing the structural integrity of the brake system of all new trucks, buses, and combination vehicles designed for roadway use and falling in the following classifications: a Truck and bus: Over 4500 kg (10000 pounds) GVWR b Combination vehicle: Towing vehicle over 4500 kg (10000 pounds) GVWR The test consists of two distinct tests: a structural endurance test followed by a structural ultimate strength test. NOTE: These two tests originated from separate procedures, and were combined in this recommended practice. Each test can be considered to be an independent evaluation of the service brake’s structure. Based on time available, cost limitations, and the desired evaluation and historical data available, either of these tests could be considered as a complete evaluation of the brake’s structure.
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
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.
This study evaluated the performance of a new approach for detecting problems with commercial vehicle brakes based on the analysis of sounds emitted during braking. Commercial vehicle brakes emit ultrasonic energy inaudible to humans as part of the friction process, and the spectral distribution of these sounds is highly dependent on the mechanical condition of the brakes. Data collected from a commercial vehicle fleet found that the acoustic signature changes as friction linings wear. This conforms with the acoustic theory that the resonant frequency of an object increases with its decrease in mass. The use of this information to inform maintenance operations is promising in that the scheduling of visual brake inspections could be based on acoustic wear patterns rather than arbitrary time intervals and the observation of anomalous signals that might indicate more immediate concerns. This could reduce maintenance labor and address issues more quickly as compared to visual inspections
It is important for assessing the service life of the braking mechanisms of passenger cars that are in operation is the establishment of the speed and the value of the permissible wear of the friction surfaces, which ensures the durability of the brake. The purpose of the study is to assess effect of area friction surfaces on resource of vehicle braking mechanisms. This will extend the service life of the disc brakes on cars. In the work, the regularities of wear of mating parts of disc brakes were established depending on the change in the geometric parameters of the friction surfaces and operating modes during their operation. It was found that the service life of disc brakes can be increased by 1.16 times with an increase in the area of frictional contact by 15 %, for passenger cars DAEWOO LANOS and LADA PRIORA. A comparative assessment of the wear of the new DAEWOO LANOS and LADA PRIORA brake pads, which perform cyclic emergency braking, is provided. Recommendations have been
Accurate measurements of brake friction materials are critical to understanding brake behaviors during testing. Current methods typically utilize a hand gauge (or a machine, in some cases) to sample various discrete points on the brake lining. This approach limits measurements to planar wear characteristics, taper and thickness, and excludes more complex measurements such as cupping. The limited number of points means that a single errant point measurement or the choice of point locations can have a large impact on the reported wear measurement. This paper will describe a method for utilizing a Coordinate Measurement Machine (CMM) fitted with a laser line scanning tool to generate a point cloud of data that can then be compared to an earlier measurement of the same piece or to a math model. This method produces thousands of data points which allows for more accurate volumetric wear calculations and color maps of the entire friction face. A gage R&R for this method is presented along
The mechanism of automobile brake hot spots is unclear, which is a problem in the brake industry. Complex coupling between friction, heat, contact, and structure is the main difficulty in revealing the mechanism of brake hot spots. This paper proposes a new way to study the mechanism of hot spots by analyzing the deformation behavior of brake discs under asymmetric mechanical loading. The actual brake is simplified into a brake disc and friction lining system, and a transient dynamic finite element model under asymmetric mechanical loads is established to analyze the deformation characteristics of the brake disc. The normal deformation of the brake disc under asymmetric mechanical loads consists of two parts: low-frequency bending deformation and high-frequency waviness deformation, which are caused by the squeezing effect of the asymmetric brake pressure on the brake disc and the constraint modal vibration of the brake disc. The influence of the rotation speed, magnitude and
One of the top problems that every Indian automobile manufacturer struggles to manage is the clutch early failure less than 30000 Km. This is mainly due to the extreme heating of the friction lining due to the real-world user profile in the Indian market and users inappropriate driving behaviors like Overloading the goods more than the manufacturer’s recommendation, non-recommended attachments and increased wheel size, Thick traffic leading to high level of clutch modulation and Clutch riding while running and launching the vehicle at higher gears. Although many simulation and testing are done during the development phase, above listed real world user profile and customer driving habits are inevitable by any automobile manufacturer. Hence the prime goal of this experimental research is to indicate or alert the user on the clutch thermal condition due to the driving habit and to encourage the user on right driving habits. This objective is met through a standalone electronic system that
Agricultural Tractors consisting of a conventional manual transmission and dry friction clutch are mostly assembled with a mechanical type of clutch release mechanism where a defined amount of free play needs to be maintained between the clutch and Release Mechanism. A defined free play is required for efficient operation of clutch, Release Bearing as well as to ensure the durability of the system. As the clutch disc wears the free play between diaphragm spring or levers (as the case may be) and the release bearing is reduced. The rate at which the clutch disc wears is dependent on many factors like working condition of the tractor, grade of the friction lining material, experience of the driver, etc. This makes it very difficult to predict the exact timeline when the free play needs to be adjusted even though an approximate indication is given in instruction manuals. In today’s situation the adjustment of the free play is carried out manually and approximately. Many times, the
A new approach for detecting problems with vehicle brakes by analyzing sounds emitted during braking events is proposed. Vehicle brakes emit acoustic energy as part of the braking process; the spectra of these sounds are highly dependent on the mechanical condition of the brake and can be used to detect problems. Acoustic theory indicates that as brake linings wear thinner the resonant frequency of the shoe or pad increases, potentially enabling the monitoring of lining wear through passive acoustic sensors. To test this approach, passive acoustic sensors were placed roadside at the exit of a transit bus facility for 9 months. The sensors collected almost 10,000 recordings of a fleet of 160 vehicles braking over a variety of conditions. Spectra of vehicles that had brake work performed during this period were analyzed to compare differences between new and worn friction linings. It was found that the spectra changes as friction linings wear, in concurrence with acoustic theory, where
This SAE Recommended Practice (RP) specifies a dynamometer test procedure to characterize wear rates of automotive service brake linings (brake shoes) and disc brake pads.
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.
This SAE Recommended Practice is intended for testing of external automatic brake adjusters as they are used in service, emergency, or parking brake systems for on-highway vehicle applications.
A study was performed to compare the performance of small and large automotive, semi-metallic, friction pads, each manufactured with one of two different calcined coke fillers. Coke #1 is a conventional calcined petroleum coke, and Coke #2 a proprietary, calcined coke manufactured from a non-petrochemical feedstock and sold by Asbury Carbons under the trade name “EcoGreen”. The subject coke materials were fully characterized, physically and chemically. Chemical characterization included a modified TCLP leaching study performed on each coke. Both coke materials are similar in their respective physical properties, including morphology, hardness, and crush strength. However, there is a significant difference in the trace metal content of the two materials, with Coke #1 containing a higher content of sulfur, calcium, iron, nickel, and vanadium than Coke #2. Nickel, vanadium, and sulfur are considered potential environmentally hazardous substances. Initial friction element evaluation was
Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed. Subsequently, the predictions are compared with
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.
Automotive clutches are rotary components which transmits the torque from the engine to the transmission. During the engagement, due to the difference in speed of the shafts the friction lining initially slips until it makes a complete engagement. Enormous amount of heat is generated due to the slippage of the friction lining, leading to poor shift quality and clutch failure. Depending on the road & traffic conditions, and frequency of engagement and disengagement of the clutch, it generates transient heating and cooling cycles. Hill fade test with maximum GVW conditions being the worst case scenario for the clutch. A test was conducted to understand the performance of the clutch, in which clutch burning was observed. The clutch lining got blackened and burning smell was perceived. The friction coefficient drops sharply to a point until it cannot transmit the torque required to encounter the slope. This further worsen clutch slippage and lead to more severe temperature rise. The major
This procedure describes a method for generating, preparing and analyzing samples of new and unused brake friction materials for their chemical constituents.
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