News & Events

LINK Unites with CARB and ERG to Conduct Large Brake Emissions Campaign

Jun 30, 2020

Ongoing Brake Emissions Test

Automotive emissions regulations inspire technological advancements, more efficient vehicles, and safer and cleaner communities. While particulate matter emissions in exhaust have significantly lessened due to strict controls, non-exhaust emissions remain unregulated and lack commonly accepted test methods. Link Engineering Company is dedicated to providing customized solutions and extensive thought leadership to the testing industry. Through our partnerships, we are leading the testing and research efforts of brake emissions from our very own testing laboratories.

As a customized testing resource, LINK recently joined the California Air Resource Board (CARB) to conduct an extensive brake emissions test campaign and engineering study at our technical center in Dearborn, Michigan. The focus of the campaign was to update CARB’s emission factors model for non-exhaust emissions of on-road light-duty vehicles while selecting a sequence that is representative of vehicle usage in the state of California. A significant and unique aspect of the study was also to obtain the ability to differentiate the effects of vehicle type and loading conditions during driving.

The project involved testing brake corners from six vehicles, relying upon approved testing protocols, test system validation, adjustment of cooling airspeeds, and interlaboratory evaluation for filter weighing methods. After conducting market analysis, all selected vehicles underwent rigorous proving ground testing to measure brake and wheel well temperatures, brake pressure, and speed, on top of various garage tests. The final phase consisted of laboratory validation and brake component testing, utilizing LINK’s enclosed full-size brake dynamometer and particulate matter sampling systems.

By employing innovative speed control systems, LINK’s inertia dynamometer was able to recreate driving representative of usage in California. During each test, LINK’s instrument cluster measured the emitted particle count, mass, and size. The regular checks on the test parameters, including the ability of the dynamometer to provide repeatable brake temperatures, produces confidence in the values measured. One aspect unique to this project was the ability to integrate the knowledge obtained from Computational Fluid Dynamics simulation with the University of Michigan. The setup also incorporated recommendations and guidelines from several EPA, U.S. CFRs, and ISO standards, including proper isokinetic sampling.

Lastly, the integration of real-time data from over 100 channels of the instrument cluster helped in creating a new standard for LINK’s ProLINK control and data acquisition software. This new method stores and synchronizes all the data retrieved from the emissions measurement systems, allows data visualization using RevDATA, and enables the automation of the test report without additional manual data processing.

In close collaboration with CARB and the Eastern Research Group (ERG), LINK is coauthoring an SAE technical paper based on this project. The findings from more than 80 tests show the effects of axle position, friction couple formulation, as well as vehicle size, type, and speed. This collection of comprehensive data and reporting will be used to further understand the area of brake emissions. The paper will provide significant insight into the newly developed California Brake Dynamometer Cycle (CDBC) – derived from an extensive database of customer usage on hundreds of vehicles, driving for several thousand miles each – as well as the particulate matter laboratory results tied to running the test cycle. Despite the challenges faced due to the absence of acceptable widespread testing methods, the results obtained in this project will assist in modernizing emission factors globally.

LINK’s expertise in researching, executing, and accurately analyzing the mostly unexplored area of brake emissions proves the innovative and technical capabilities we possess for advancing the testing industry. We are dedicated to the growth and evolution of the testing industry, providing innovative solutions that our customers rely on for testing and developing the next generation of equipment and products.

Read more about our brake emissions testing efforts, including our Model 6300 Brake Emissions Test System, on our website.

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Type of TestTest HighlightsEquipment UsedExample Procedures
Chemical TestingMeasurement of copper, asbestos and other elements in brake friction materialsICP-OES / PLMJ2975
Materials TestingPhysical properties including quality control for friction, wear, compressive strain, shear strength, corrosion resistance, swell and growthChase Machine / Compressibility Machine/ Shear Machine / Corrosion Chamber / Environmental Chamber / OvenJ661, ISO 6310, ISO 6311, ISO 6312, ABNT NBR 9301, ABNT NBR 5505, ABNT NBR 5537, ASTM B117
Frequency ResponseComponent Frequency ResponseLaser Vibrometer Test StandSAE J2933, J3001, J2598, L-4375
Structural Fatigue and
Breaking strength, cyclic fatigueServo Hydraulics, Torque FlexJ2995, C419, C441, GMW18022
Caliper FingerprintingCaliper characteristics such as knockback, rollback, fluid displacement, deflection...Caliper Test Bench / Brake DynamometerL-4177, PF.90257
Brake Drag and DTVResidual drag, disc thickness variation, brake feel and vehicle fuel mileageOff Brake Drag Stand / Brake DynamometerJ2923, GMW14926, GMW14351, PF.90257, L-13080
PerformanceHydraulic, air and electric brakes, friction levels, stopping distance, corrosion, cleanability, brake torque variation, rotor cracking, regulation, stability control, coastdownBrake Dynamometer, Model 4000 DASJ2784, J2928 IS026867, GMW14985, PF.90210, PF.90244, L-405, FMVSS 121, FMVSS 122, FMVSS 105, FMVSS 135, FMVSS 126, FMVSS 136, ECE R13H, AMS
WearRotor wear, drum wear, lining wear, DTV, durability, city traffic, suburban trafficBrake Dynamometer, Model 4000 DASJ2707, USCT, L-423, PF.90244, Los Angeles, Detroit, Phoenix, Birmingham, Marquette
NVHBrake squeal during drag and decel events at different temperatures, pressure and torque levelsNVH Brake DynamometerJ2521, L420, 1430, GMW17427, PF. 90244
Brake EmissionsBrake dust particle size, count, concentration and massBrake DynamometerWLTP, CARB, Duty cycle


Type of TestTest HighlightsEquipment UsedExample Procedures
Wheel BearingWater intrusion and durability when exposed to mud and saltBearing Test StandLINK Hub and Bearing, GMW16306, GMW16310
Passenger car, sport/performance and open bed vehicle wheel bearing spallingBearing Test StandGMW16311, GMW16308, GMW16309
Brinelling resistance validates long-term reliability/durabilityBearing Test StandGMW16305
Rotary fatigue lifeRotary Fatigue MachineGMW16325
Wheel HubRotary bending fatigue life characteristicsRotary Fatigue MachineGMW14249
Hub/BearingEvaluate hub and bearing performance, durability, seals and NVH when exposed to extreme environmental effects such as temperature and mud/salt solutionBearing Test Stand/Rotary FatigueTIP-000037A, LINK Hub and Bearing, SAE J1095, LINK Impact
Hub FatigueHub fatigue using biaxial loadingBiaxial Test StandSAE J2562


Type of TestTest HighlightsEquipment UsedExample Procedures
ChemicalEvaluates filiform corrosion on painted aluminum wheels and painted aluminum trimICP-OESASTM E3061
Wheel Corrosion and CoatingsEvaluates filiform corrosion, tape adhesion, degree of rusting on painted aluminum wheels and painted aluminum trimCorrosion ChamberSAE J2635, ASTM B368, ISO 9227,
ISO 2409, ASTM D3599,
ABNT NBR 11003, ASTM D610,
ASTM D1654
Wheel FatigueLoad simulation test of aluminum alloy wheelsBiaxialBMW QV36026, SAE J2562, FORD
L-307, GMW14340
Dynamic Cornering Fatigue and Dynamic Radial Fatigue - Steel wheelsEccentric Mass and RadialABNT NBR 6750
Rotational fatigue, Radial load fatigue and biaxial load fatigue of steel and aluminum wheelsEccentric Mass, Radial and BiaxialABNT NBR 6751
Dynamic Cornering Fatigue and Dynamic Radial Fatigue and Impact resistance of temporary use and normal highway use aluminum wheelsEccentric Mass, Radial and Drop TestABNT NBR 6752
Wheel Radial FatigueRadialGMW14909
Wheel ImpactWheel Inboard Rim Flange Vertical ImpactDrop TestGMW15321
Wheel radial impactDrop TestCETP 04.04-L300
Wheel Lateral ImpactDrop TestGMW14910, SAE J175
Wheel StiffnessFrequency Response Function (FRF)Frequency ResponseGMW14876
Deformation of the wheelServo HydraulicsJ2315
Center cap heat
Center Cap deformation under elevated temperature conditionsBench TestBrake Heat Center Cap


Type of TestTest HighlightsEquipment UsedExample Procedures
Parking ForcesAllows proper sizing of power steering componentsForce and MotionLINK Parking Forces
Tire FootprintDetermines the contact patch geometryForce and MotionTire Footprint
Tire Modeling
Determine tire inertia which is then used Ftire and other models and simulationsInertia MachineLINK Tire Inertial Properties
On-center parking effort test for Ftire inputForce and MotionSWP
Determine static stiffness (X, Y, Z, Alpha) for Ftire inputStatic Stiffness MachineSAE Static Stiffness
Determine how the tire envelopes an obstacleCleat MachineJ2731
Measure the forces and moments generated at a high frequency response spindle when the tire impacts a cleatCleat MachineJ2730
Braking and Cornering PerformanceDetermine the straight line braking performance of a tireForce and MotionJ2673
Determine the free rolling cornering properties of a tireForce and MotionSAE TIME, J1987, SWP
Measure the combined cornering and braking performance of a tireForce and MotionJ2675
Tire StiffnessMeasure rolling vertical stiffness of a tire at speedRolling Vertical Stiffness
Rolling ResistanceMeasure tire rolling resistance using a drumForce and Motion, Rolling ResistanceJ1269, J2452
Tire WearAssess tire wear in the labForce and MotionLINK Wear Test
Tire NVHTest tire sizzle, cornering noise, pass-by noise, steering wheel dither, freeze crack impacts, high speed uniformity and imbalance sensitivityForce and Motion, Dynamometer, Model 4000 DASNoise, Vibration, Harshness