Link Report

		How to read and understand the aftermarket standard SAE J2430/B.E.E.P.^Ó test report
Formulators, process designers, plant managers, application engineers, quality control managers, purchasing agents and business unit managers can benefit from SAE J2430/B.E.E.P.^Ó testing		Introduction Brake effectiveness evaluation has always been a demanding automotive engineering task. The introduction of the SAE-J2430 SURFACE VEHICLE STANDARD in 1999 [1] and the adoption of it by the Brake Manufacturers Council as the basis for the Brake Effectiveness Evaluation Procedure for friction material used on passenger cars and light truck brake systems makes this task easier. It is a single-ended inertia dynamometer test reviewed and endorsed by the brake industry and supported by almost 1,000 dynamometer tests and 50 fully instrumented vehicle tests. The SAE J2430/B.E.E.P. Test procedure resembles the main sections of the Federal Motor Vehicle Safety Standards 105 [2] and 135 [3]. Not having a reference material on the other axle, it gives a high degree of repeatability and consistency from test to test. Further introduction of the Brake Effectiveness Evaluation Procedure by the BMC friction materials committee, creates a reliable framework to assess actual performance of a friction material. The acceptance criteria are derived from the FMVSS requirements and studies performed by the University of Michigan Transportation Research Institute. Driving forces for this industry effort are: stringent new brake performance requirements, increasing interest in the aftermarket customers in standardized test procedures open to the industry as a way to reduce testing costs and reduce development times, recent safety issues and the industry interest in self-verification and overall technological improvement.
The BMC/FMC recognizes and supports the use of the SAE J2430 as a basis for meeting the BMC/FMC objective		"The BMC Friction Material Committee resolves that aftermarket brake friction materials should not deteriorate vehicle braking performance below the applicable federal motor vehicle safety standard, and recognizes that on-vehicle, dynamometer, or other equivalent testing, engineering or computer analyses may be employed by manufacturers of replacement friction in making good faith efforts to determine FMVSS performance."[4]

Note:		This is a document for technical reference only. Link Engineering Co., Link Testing Laboratories., Inc. or the BMC shall be held harmless for product liability including, but not necessarily limited to, product design, manufacture, performance and acceptability for use.
SAE J2430 tests friction materials one at a time, following the market practice of changing brake linings one axle at a time.		Why a SAE standard for dynamometer testing “SAE J2430 is an improvement over SAE J661/J866 as a friction material effectiveness characterization test of replacement brake linings. SAE J661 uses a one-inch square sample running against a large drum and is known to have shortcomings for characterizing the vehicle performance of different types of automotive brake linings.” [1] A single-ended inertia dynamometer test has among others, the following advantages over other types of tests [5]: · Uses vehicle specific hardware and test conditions derived from detailed vehicle tests. · Tests only one material at a time without the influence of a reference material on the other axle that affects repeatability and accurate assessment of the material tested. · Specifies, in detail, control inputs and permits in-depth assessment on how the test was performed. Brake cooling, which is critical in performance tests, is also properly defined. · Cost-effective when compared to a full vehicle test. · Developed in more than 7 years of continuous testing and close analysis of results by Original Equipment Manufacturers, suppliers, consultants and friction manufacturers. · Takes advantage of the expertise available through the SAE committees structure and approach to develop and validate testing protocols with detailed peer reviews in an open discussion forum. Periodical updates keep standards current with the application and testing industry. · Can be run on single-ended dynamometers. Single-ended dynamometers far exceed the amount of dual-ended dynamometers available throughout the industry.
Performance limits are based on stopping distance and maximum pedal force defined on the federal requirements.		Why the Brake Manufacturers Council performance limits? As a second phase of the SAE J2430/B.E.E.P.^Ó program, the friction materials committee developed a set of criteria consistent with the FMVSS vehicle test requirements [5]. SAE J2430 does not include acceptance or performance limits, so its applicability for effectiveness characterization required a mathematical modeling of the vehicle dynamics and its corresponding relationship with the federal stopping distance and pedal force requirements. The BMC also developed a test report format in order to present test data in a consistent and repeatable way. Performance criteria include [4]: · Average of ramp applications should be within the FMVSS effectiveness space requirements. Regressed specific torque within the limits allowed for stopping distance requirements, maximum pedal force and brake balance. Over-effective performance is also compared to maximum limits on pedal force and deceleration limits. · Cold Effectiveness and fade snubs within acceptable limits of deceleration and maximum pedal force. · Hot Effectiveness stops above the minimum deceleration requirements within pedal force limits. · Post-test structural integrity to assure friction material is able to go through the test without mechanical failure or detachment from the backing plate.
Brake balance between front and rear axles is the basic criteria for the inertia split calculation The BMC has external consultants to audit how a valid test is run Control program parameters, performance limits and acceptance criteria are defined based on the federal requirements, not the original equipment friction material or any reference material		How a vehicle is made available for SAE J2430/B.E.E.P.^Ó testing SAE J2430/B.E.E.P.^Ó testing requires specific test conditions and hardware information before the actual test can be performed. Vehicles to be tested should meet some initial criteria: · Current production on-road vehicle · Up to 3,500 kg gross vehicle weight · Be available for the corresponding floor-checks and measurements Vehicles can be added based on BMC platform development committee request to any approved testing facility or direct customer requirement as part of their engineering or marketing validation programs. Link Testing Laboratories., Inc. also develops vehicles independently to make them available to the industry for regular testing. Information is used to: gather hardware information to build fixtures for front and rear axle friction materials testing, define the required inertia for regular testing based on brake balance, determine the vehicle specific parameters for the control program and performance limits for the acceptance criteria shown on the report. Procedures for obtaining the vehicle information follow Federal Test Codes requirements. [5]. Vehicle data can be grouped as follows: · Physical dimensions and weights: wheelbase, tire rolling radius, brake effective radius, brake disc or drum dimensions, center of gravity height, gross and lightly loaded vehicle weight. · Hydraulic system pressure levels with and without power assist, pressure profiles for 135 N/s pedal force ramp rate, knee point when proportioning valve available, booster runout pressure, pressure levels at 667 N and 500 N pedal force for FMVSS 105 and 135 respectively certified vehicles and 1,000 N maximum pedal force corresponding pressure for the effectiveness section per FMVSS pedal force limit. · Brake hardware part numbers and FMSI identification for friction materials, both front and rear. Link Testing Laboratories, Inc. performs internal testing using the original equipment friction material to fine-tune the computer control program for the dynamometer and have an exemplar data set to develop the test report format. Control program parameters, performance limits and acceptance criteria are defined based on the federal requirements, not the original equipment friction material or any other friction product. Other options to develop a vehicle for regular SAE J2430/B.E.E.P.^Ó testing is via a testing program agreement with Link Testing Laboratories., Inc. Customers with floor check capabilities and the proper inertia dynamometer with the technical capabilities specified in the current SAE J2430 SURFACE VEHICLE STANDARD can develop vehicles for testing on their own. *Link Testing Laboratories B.E.E.P.^Ó task force* can assist with training, control program development and screening programs ranging from basic awareness sessions to full in-house testing capabilities.
SAE J2430/B.E.E.P.^Ó test can be used to characterize effectiveness on friction materials -brake pad or brake lining- or components –rotors, drums, calipers-		What is needed to perform a SAE J2430/B.E.E.P.^Ó test Running a regular SAE J2430/B.E.E.P.^Ó on any of the available vehicles only requires sending parts, indicating the amount of tests to be performed and arranging the test schedule by phone or e-mail. Unlike other test procedures where test conditions may vary from customer to customer, SAE J2430/B.E.E.P.^Ó test conditions are pre-defined for each vehicle. Parts required to run a test are: · Friction material for effectiveness characterization. Rotor or drum and hardware used are original equipment level. · Rotor or drum for effectiveness characterization. Friction material and hardware used are original equipment level. Test report is submitted in Adobe Acrobat format along with a Microsoft Excel spreadsheet. Typical turnaround for a SAE J2430/B.E.E.P.^Ó test is one to two weeks.
	Brake inertia dynamometers Inertia dynamometers are brake-testing equipment used to perform a variety of testing ranging from quick friction coefficient analysis for coated rotors to FMVSS 105 or 135 simulations. Performance, durability, capacity and noise tests are the most common tests performed. Single-ended dynamometers utilize brake components from one corner of the vehicle in order to subject the components to a series of brake applications defined in the test procedure. The vast majority of inertia dynamometers procedures (SAE, JASO, ISO, AK, FMVSS, JIS or proprietary) used by original equipment suppliers, friction vendors and component manufacturers are designed for single-ended dynamometers. Main components of an inertia dynamometer are: main drive, inertia section, brake enclosure, cooling air system, computer control console and fixture with brake components for testing. The main drive accelerates the mass inertia that simulates the vehicle’s kinetic energy and then the brake is applied to stop or reduce the speed of the mass. The motor can be also used to drag the brakes to simulate a constant downhill descent. If the brake is applied without rotation, parking brake forces can be measured. Typical sensors and signal conditioning include channels for reading speed, torque, pressure, fluid displacement and temperature. Noise testing requires a noise enclosure and microphones for brake noise data collection. Modern Inertia dynamometers are controlled with Microsoft Widows based software and can simulate certain levels of inertia. Pressure profiles and complex control algorithms are also available. Typical brake applications can be controlled by pressure, torque, deceleration or drag by pressure. The start of the brake application can be by initial temperature or cycle time. The release of the brake application can be by speed, torque, temperature or elapsed time.

Maximum value for front brake regressed specific torque.

Minimum value for front brake regressed specific torque.

Actual friction material performance level.

UMTRI Line

Brake Balance Line

Stopping Distance Line

No-power Line

Figure 1. Effectiveness space for Ford Taurus 2000 with height sensing proportioning valve. FMVSS 105 certified. Being within the upper and lower limits, this friction material meets the BMC Effectiveness space criteria. When a brake is tested using SAE J2430/B.E.E.P.^Ó, test report for a front axle will be always shown as a horizontal line corresponding to the average of 27 effectiveness ramps applied during the test. When a rear brake is tested, a vertical line will indicate the same average on that axle.

Effectiveness space assessment is based on the Effectiveness ramps run at 50, 100 and 160 kph up to 0.8 g, maximum pedal force of 1,000 N or release speed per the federal requirement-

Simplified effectiveness space analysis and performance limits

Figure 1 illustrates the effectiveness space derived from the vehicle dynamics and hydraulic system pressure level limits. A given vehicle should be able to meet stopping distance requirements without exceeding limits on the pedal force at the same time, based on the FMVSS requirements. The former is expressed as torque or deceleration level requirements and the latter as pressure limits.

Figure 1 illustrates the typical effectiveness space or performance window for a given vehicle. Each line indicates, for a given regressed specific torque in one brake (front or rear) what is the minimum regressed specific torque required on the other. The only exception to this is the UMTRI line that indicates the maximum level of regressed specific torque on both axles. In order to obtain torque levels, specific torques values need to be multiplied by a given pressure, which may vary depending upon the analysis or limit you need to assess.

Basic mathematical relationships between front and rear axles for performance limits definition

Basic physical laws of motion and vehicle dynamics govern the relationship between the braking forces on both axles of a given vehicle. Even though the general equations are the same and the federal requirements on which they are based are valid for vehicles up to 3,500 kg of gross vehicle weight, parameters needed to determine the specific numerical values are obtained on the vehicle floor-checks and measurements.

Following we illustrate the main equations useful for determining the different curves and lines that create the effectiveness space on a given vehicle. In order to keep this section simple, analysis is made only for vehicles not equipped with proportioning valve. Detailed mathematical analysis can be found in the extensive brake systems literature. [6] And [7].

F_x = W x a

Equation 1

F_x

Force developed when a mass changes speed in the longitudinal direction (direction of travel). In SAE J2430/B.E.E.P.^Ó forces are equated to braking or deceleration forces.

Weight undergoing a change in speed. In SAE J2430/B.E.E.P.^Ó mass can be the gross vehicle weight (curb weight plus driver, instrumentation and payload up to rated capacity on each axle) or the lightly loaded vehicle weight (curb weight plus driver, instrumentation, full fuel tank and 182 kg for FMVSS 105 vehicles [2] or 180 kg for FMVSS 135 vehicles [3]).

Rate of change in speed. In SAE J2430/B.E.E.P.^Ó is taken as declaration up to 0.8g.

Multiplying by the tire rolling radius (rr) on both sides of the equation, we obtain braking torque for one axle or half vehicle.

M = F_x x rr = (W x rr x a) / 2

Equation 2

Total braking torque for half the vehicle. Can apply for one axle at a time.

Total braking torque in half the vehicle is equal to the braking torques coming from axles, front and rear.

M = M_f + M_r

Equation 3

Total braking torque expressed as the sum of both braking torques.

M_f

Total braking torque on the front brake.

M_r

Total braking torque on the rear brake.

Dividing torque by the pressure at the same point in time, we obtain what is called in SAE J2430/B.E.E.P.^Ó specific torque. This term is equivalent to the brake factor in FMVSS 135 when calculated as a linear regression.

RST = M / p or M = RST x p

Equation 4

RST

Regressed specific torque.

Pressure at the same point in time that torque is measured.

Replacing equations 2 and 4 on equation 3 gives a generic relation between the specific torques, pressures and deceleration for half vehicle taking into account front and rear brakes.

RST_fx p_f + RST_rx p_r= (W x rr x a) / 2

Equation 5

Braking force as a function of specific torques and hydraulic pressures. When the vehicle is equipped with a proportioning valve, pressures between front and rear axles may differ depending upon the pressure level.

Performance limits and the effectiveness space

The effectiveness space has basically four limiting conditions that can be used to assess if a particular friction material meets the BMC acceptance criteria, giving consistency with the federal requirements.

The sections from the test used to assess this performance are:

0008: Effect. #1. Post Burnish at 50 km/h Ramp

5 stops

0009: Effect. #1. Post Burnish at 100 km/h Ramp

5 stops

0015: Recovery ramp at 100 km/h

2 stops

0017: Final Effectiveness at 50 km/h Ramp

5 stops

0018: Final Effectiveness at 100 km/h Ramp

5 stops

0019: Final Effectiveness at 160 km/h Ramp

5 stops

“To meet this FMVSS 135 acceptance criterion, a line representing the measured regressed specific torque average for ramp applications, should fall within the calculated effectiveness space requirement. The use of a line emphasizes that effectiveness of the material on the other axle is typically unknown at the time of a brake job.” [4]

· University of Michigan Transportation Research Institute (UMTRI) Limit for maximum pedal gain of 178 N and 1.0 g deceleration level at the lightly loaded vehicle weight. The purpose of this limit is to establish a level at which a friction material would become too effective and would make braking uncomfortable or too prone to locking even at low decelerations levels encountered in regular driving situations. The UMTRI effectiveness limit was based on an extensive research performed on vehicles tested under FMVSS test codes.

RST_fx p_f ^UMTRI + RST_r x p_r^UMTRI=
( W^LLVW x rr x a^UMTRI) / 2

Equation 6

General equation for relating front and rear regressed specific torques based on the UMTRI values.

p_f ^UMTRI

Pressure at the front brake at 178 N pedal force.

p_r ^UMTRI

Pressure at the rear brake at 178 N pedal force.

W^LLVW

Lightly loaded vehicle weight.

a^UMTRI

Deceleration level for the UMTRI limit taken as 1.0g

No intersecting point for a front and rear brakes combination is considered feasible above this line. For front brakes tested independently, the line representing the averaged regressed specific torque should not be above the intersecting point between the FMVSS stopping distance limit and the UMTRI line.

· FMVSS No-power assist stopping distance limit. The full deceleration developed by the brake (braking torque) should be able to stop a vehicle in 168 m from an initial speed of 100 kph without exceeding a pedal force of 667 N on FMVSS 105 or 500 N on FMVSS 135 certified vehicles at its gross vehicle weight with the power assist system fully depleted. Using the vehicle dynamics equations defined in the FMVSS code, the following relationship between stopping distance, initial speed, deceleration and reaction time can be established.

a ^NP = V² / [ 2 x (X ^NP – 0.72 x V / 2)]

Equation 7

a ^NP

Average deceleration after reaction time or ramp time is elapsed. The term 0.72 x V / 2 accounts for the increased traveled distance during the drivers reaction time. In SAE J2430/B.E.E.P.^Ó testing this distance is compensated by the ramp time required to get to the target deceleration. a^NPis required to be 0.249g following the FMVSS requirements.

Initial vehicle speed at the start of the braking operation. 96.6 km/h for FMVSS 105 vehicles and 100 km/h for FMVSS 135 certified vehicles.

X ^NP

Maximum allowable stopping distance. 139 m for FMVSS 105 vehicles and 168 m for FMVSS 135 certified vehicles.

RST_f x p_f^NP + RST_rx p_r^NP=
( W^GVW x rr x a^NP ) / 2

Equation 8

General equation for relating front and rear regressed specific torques based on the FMVSS no-power assist stopping distance limit.

p_f ^NP

Pressure with power assist fully depleted at the front brake at 667 N pedal force for FMVSS 105 certified vehicles and 500 N pedal force for FMVSS 135 vehicles

p_r ^NP

Pressure with power assist fully depleted at the rear brake at 667 N pedal force for FMVSS 105 certified vehicles and 500 N pedal force for FMVSS 135 vehicles

No intersecting point should fall on the left side of this limit.

In any case, front axle regressed specific torque shall not fall below the intersecting point of this limit and the FMVSS brake balance limit. even for ABS or FMVSS 105 vehicles. If this happens, it would mean brake is not capable of meeting the no-power assist stopping distance due to rear wheel lock-up and the consequential reduced total braking force.

· FMVSS stopping distance limit. The federal requirement states that a vehicle shall be capable of stopping in 70 m or less from an initial speed of 100 kph and initial brake temperature at or below 100 ^oC for an FMVSS 135 certified vehicle at its gross vehicle weight. This line can be a straight or curved line. Straight-line limits apply to vehicles not equipped with proportioning valves or vehicles using height sensing proportioning valves. Curved-line limit apply to vehicles with proportioning valve.

a ^SD = V² / [ 2 x (X ^SD – 0.72 x V / 2)]

Equation 7

a ^SD

Average deceleration after reaction time or ramp time is elapsed. The term 0.72 x V / 2 accounts for the increased traveled distance during the drivers reaction time. In SAE J2430/B.E.E.P.^Ó testing this distance is in fact compensated for the ramp time required to get to the target deceleration. a^SD is calculated as 0.656g following the FMVSS requirements.

Initial vehicle speed at the start of the braking operation. 96.6 km/h for FMVSS 105 vehicles and 100 km/h for FMVSS 135 certified vehicles.

X ^SD

Maximum allowable stopping distance. 62.2 m for FMVSS 105 vehicles and 70 m for FMVSS 135 certified vehicles.

RST_f = RSTrx (1-Φ) / Φ

Equation 8

General equation for relating front and rear regressed specific torques based on the FMVSS no-power assist stopping distance limit. For vehicles equipped with proportioning valve, additional mathematical analysis is required.

Φ = T_r/ T_t

Equation 9

Braking torque distribution calculated using a peak friction value of 0.9 and a deceleration of 0.656g. Peak friction also represents the ratio between the horizontal braking force and the vertical load, applied on the wheel. The vertical load comprises static loading plus dynamic weight transfer due to deceleration.

T_r

Front brake torque. See equation 2

T_t

Total braking torque for half vehicle. See equation 2

No intersecting point should fall on the left side of this limit.

FMVSS brake balance limit. During the ramp applications up to 0.8 g deceleration, vehicle should not exhibit a rear brake lock up prior to lock up in the front wheels. Vehicles certified to FMVSS 105 do not need to fulfill this requirement. FMVSS 135 certified vehicles equipped with ABS could exhibit an impending rear lock-up condition, shown as an intersecting point between front and rear regressed specific torque lines on the rigth hand side of this line.

RST_f = RSTrx (1-Φ) / Φ

Equation 10

General equation for relating front and rear regressed specific torques based on the FMVSS brake balance limit. For vehicles equipped with proportioning valve, additional mathematical analysis is required.

Φ = T_r/ T_t

Equation 11

Braking torque distribution calculated using a deceleration of 0.8g.

No intersecting point should fall on the right side of this limit for vehicles FMVSS 135 certified not equipped with ABS. FMVSS 135 certified vehicles equipped with ABS could exhibit an impending rear lock-up condition, shown as an intersecting point between front and rear regressed specific torque lines on the rigth hand side of this line.

In SAE J2430/B.E.E.P.^Ó pedal force limits are expressed as hydraulic pressure levels-

Cold Effectiveness

Cold Effectiveness assessment serves the purpose of determining the brake capability to meet the stopping distance requirement without exceeding the maximum allowable pedal force on the FMVSS. See figure 2.

Test section used to assess this criteria is:

0010: Post Burnish Cold Effectiveness

6 stops

“To meet this criterion, each of the six cold effectiveness stops should meet the specified sustained torque within a prescribed maximum pressure corresponding to the FMVSS specified pedal force.” [4]

Actual torque developed

Maximum pressure allowed

Actual pressure required

Figure 2. Cold Effectiveness assessment. With actual pressure required lower than the maximum allowed, this friction material meets the BMC Cold Effectiveness criteria.

Fade snubs are used to heat the brakes for assessing its effectiveness at high temperature.

Fade snubs

Fade snubs assessment serves the purpose of determining the brake capability to meet the FMVSS heating cycle requirement without exceeding the maximum allowable pedal force. See figure 3.

Test section used to assess this criteria is:

0011: Fade Heating Cycles

15 snubs

“To meet this acceptance criterion, each fade snub should meet the specified sustained torque within the applicable pedal force requirement.” [4]

Actual torque developed

Maximum pressure allowed

Actual pressure required

Figure 3. Fade snubs assessment. With actual pressure required lower than the maximum allowed, this friction material meets the BMC fade snubs criteria.

Hot Effectiveness is useful to assess how a friction material performs at high temperatures.

Hot Effectiveness stops

Hot Effectiveness stops are performed immediately following the heating snubs. They are based also on stopping distance requirements and pedal force limits. See figure 4.

· First stop is run with a pressure control from the best cold effectiveness stop. For this purpose, since all cold effectiveness stops are run at the same torque level, the best cold effectiveness is the one requiring the least amount of sustained pressure.

· Second stop is run at the maximum allowable pedal force: 667 N for FMVSS 105 certified vehicles and 500 N for FMVSS 135 vehicles.

Test section used to assess this criteria is:

0012: Hot Performance Effectiveness

2 stops

“Acceptance criteria for both hot stops are that the sustained torque meet or exceed 60% of the six stop average cold effectiveness sustained specific torque.” [4]

Lowest cold effectiveness pressure.

60% of cold effectiveness average torque.

Actual torque developed by the brake

Figure 4. Hot effectiveness stops assessment. Lower left hand window. With actual torque output higher than the minimum level required, this friction material meets the BMC hot effectiveness criteria.

FMVSS tests or SAE J2430/B.E.E.P.^Ó are not intended to replicate regular street driving conditions

Structural integrity

Experience shows that a material should be able to withstand the different stops with its corresponding speed, torque and temperature stresses seen during the test.

This structural integrity assessment is performed normally at the end of the test by visual inspection

“To meet this criterion, tested friction parts should exhibit no detachment or fracture other than minor surface cracks that do not impair attachment of the friction facing. Friction facing tear out (complete detachment of the lining) should not exceed 10% of the lining on any single friction element.” [4]

FMVSS test are used to assess safety and regulatory compliance. SAE J2430/B.E.E.P.^Ó testing is consistent with the FMVSS requirements.

BMC acceptance criteria summary

Standard SAE J2430/B.E.E.P.^Ó test report includes a summary table that clearly indicates the acceptance criteria. This gives a quick summary of the different BMC acceptance criteria as to where to focus for additional detailed analysis or further testing. See figures 5 and 6.

Users of a typical test report are strongly encouraged to read and understand the report beyond the simple review of the criteria table.

Since SAE J2430/B.E.E.P.^Ó does not use a reference material on the other axle, certain materials give repeatability as high as 95% on several tests, run several years apart.

Figure 5. Friction material complying with all the BMC acceptance criteria.

Figure 6. Friction material not complying with all the BMC acceptance criteria.

SAE J2430/B.E.E.P.^Ó test report is delivered as an
e-Report via e-mail-

SAE J2430/B.E.E.P.^Ó tabular test report. Figures 7-10

Besides the initial pages of the test report that gives details on the test conditions, and the graphical pages, tabular pages give detailed values for each stop, except for every 10 stops in the burnish.

Test report column header description

Test report header

Description

Range or value reported

STOP

Stop number within a given section

Stop number

INISP

Initial speed (km/h)

Speed at start of brake applies

FNLSP

Final speed (km/h)

At end of data collection. Varies with type of brake apply

DIST

Stopping distance (m)

From brake apply to end of data collection

CYCL

Cycle time (s)

From start of one brake apply to the start of the next

SUSTQ

Sustained torque by distance (N m)

Torque averaged by distance using the mean fully developed deceleration (after 97% of setpoint), brake inertia and rolling radius

AVGTQ

Average torque by distance (N m)

Torque averaged by distance for the data collection range.

MXTQ

Maximum torque (N m)

Maximum torque during the brake applies data collection

SUPR

Sustained pressure by distance (kPa)

Pressure averaged by distance from 97% of setpoint to end of data collection range

AVPR

Average pressure by distance (kPa)

Pressure averaged by distance for the data collection range

MXPR

Maximum pressure (kPa)

Maximum pressure during the brake applies data collection

AVSPTQ

Specific torque averaged by distance (N m/kPa)

Average torque divided by average pressure

ROTI

Initial rotor or drum temperature (^oC)

Rotor or drum temperature at start of brake apply

ROTF

Final rotor or drum temperature (^oC)

Rotor or drum temperature 5 s after brake release

T2F

Final primary/leading/ inner temperature (^oC)

Temperature on the specific friction material 5 s after brake release

T3F

Final secondary/trailing/outer temperature (^oC)

Temperature on the specific friction material 5 s after brake release

RGSPTQ

Regressed specific torque (N m/kPa)

Regression analysis to find the best linear fit for the torque over pressure ratio

PHO

Hold off pressure (kPa). This is a calculated, not a measured value. The closer to 0 the more stable the friction material is.

Calculated pressure for 0 torque based on the linear regression

R²

Coefficient of determination. The closer to 1 the more stable the brake is.

Average ratio between actual and calculated values of the regression for specific torque

INERTIA

Brake inertia (kg m²)

Calculated brake inertia using the work performed during the data collection range. (Work is taken as the reduction in kinetic energy and absorbed by the brake)

Regressed specific torque, hold-off pressure and correlation are given only for ramps.

Line Callout 4: Regressed specific torque, hold-off pressure and correlation are given only for ramps.

For ramp applies, when final speed is higher than 8 km//h, means the brake reached first a pressure or a torque limit.

Line Callout 4: For ramp applies, when final speed is higher than 8 km//h, means the brake reached first a pressure or a torque limit.

Sustained levels should always be higher than average levels.

For ramp sections, sustained values are not indicated.

Line Callout 4: Sustained levels should always be higher than average levels.
For ramp sections, sustained values are not indicated.

Figure 7. Tabular data for Instrument Check sections

· Instrument check stops are useful for verifying proper dynamometer control program settings.

· Torque control instrument check stops are also used to assess torque variation and hardware conditions especially in drum brakes.

· Ramps are applied as pressure ramps corresponding to 135 N/s pedal force ramps. Link Testing Labs., Inc. control software can resemble proportioning valve and booster runout within 5% accuracy compared to the actual vehicle’s hydraulic system.

· Sections 5 and 6 can be also used to assess what is called “Green Effectiveness” in the material. Comparison with ramp sections post-burnish (sections 8 and 9) and final ramps (sections 17, 18 and 19) can give a detailed assessment of burnish sensitivity, post-fade sensitivity and speed sensitivity (50, 100 and 160 km/h)

· Burnish section goes right after these instruments check sections.

This material exhibits a very stable performance at different speeds and for the whole ramp portion.

Line Callout 4: This material exhibits a very stable performance at different speeds and for the whole ramp portion.

Heating cycles take the rotor or drum from 55 ^oC up to temperatures sometimes higher than 600 ^oC

Line Callout 4: Heating cycles take the rotor or drum from 55 oC up to temperatures sometimes higher than 600 oC

FMVSS requires sustained torque to be 60% or higher then the cold Effectiveness average

Line Callout 4: FMVSS requires sustained torque to be 60% or higher then the cold Effectiveness average

Figure 8. Tabular data for effectiveness, cold effectiveness, fade heating snubs and hot effectiveness sections.

· Cold Effectiveness is one of the most important sections during the test. It has a specific BMC criterion that applies to it and is the basis for the hot performance section and assessment.

· In-stop data analysis is a very useful tool for development engineers, raw material suppliers and formulation designers. Link Engineering Co. software Revdata Plus is available upon request for this purpose.

· Fade snubs final temperature and specific torque variation during the section, sheds light regarding the temperature performance for the friction material and the impact of different raw materials.

· An increasing pressure requirement means a higher pedal force required at high temperature stops during regular driving.

Column header description is given at the end of the test report

Line Callout 3: Column header description is given at the end of the test report

Speed sensitivity can be seen, as higher pressure required getting to the same torque level.

RGSTQ shows the same behavior.

Line Callout 4: Speed sensitivity can be seen, as higher pressure required getting to the same torque level.
RGSTQ shows the same behavior.

Figure 9. Reburnish and final effectiveness sections.

· Reburnish is used to recondition the brakes for the final effectiveness sections.

· Final effectiveness provides also insight regarding speed sensitivity up to 160 km/h.

· A stable material, should exhibit little variation after the heating sections on the torque output or effectiveness values (expressed as specific torque).

· SAE J2430/B.E.E.P.^Ó test report also has an exception report to pinpoint main variation during the test from test procedure requirements regarding pressure, temperature, cycle time and sustained torque levels.

Figure 10. Wear information.

· Even though SAE J2430/B.E.E.P.^Ó is not a wear test, detailed analysis of the wear characteristics of the friction material and also the wear imposed on the rotor or drum can be very valuable.

· For formulation comparison or process stability analysis, wear comparison between different tests can be performed.

· Detailed wear thickness measurements and weight loss are given for brake pads or brake linings, rotor or drum. Thickness and weight loss are given too along with roughness data.

· Since SAE J2430/B.E.E.P.^Ó does not use a reference material, energy input is always the same for tests performed on the same vehicle. Also SAE J2430/B.E.E.P.^Ó test is performed with new original equipment hardware and components.

Brake Manufacturers Council Members

Akebono Corporation
Anstro Manufacturing, Inc.
Balatas American Brakeblok
Better Brake Parts, Inc.
Capital Tool and Design Limited
Consorcio Mexicano de Empresas, S.A.
Continental Teves
Dana Corporation
Delphi Energy & Chassis
DMC Technical Products
Fasa Friction Laboratories Inc.
Federal-Mogul Corporation
Fricciones Tecnicas Y Maquinados S.A.
Friction Division Products, Inc.
Hawk Performance Group
Hemispheres International Mfg. Co.
Honeywell
Morse Automotive Corporation
MSC Laminates and Composites Inc.
Nisshinbo Automotive Corporation
Nucap Industries Inc.
Performance Friction Corporation
Robert Bosch Corporation
Sumitomo Electric Automotive, Inc.
Tabco Auto Brake Co. Ltd.
TMD Friction, Inc.
TRW
Universal Automotive Industries

Who is behind SAE J2430/B.E.E.P.^Ó

About SAE

What do cars, aircraft, trucks, off-highway equipment, engines, materials, manufacturing, and fuels have in common? SAE. The Society of Automotive Engineers is your one-stop resource for technical information and expertise used in designing, building, maintaining, and operating self-propelled vehicles for use on land or sea, in air or space.

Who we are & what we do

Nearly 80,000 engineers, business executives, educators, and students from more than 97 countries form our network of members who share information and exchange ideas for advancing the engineering of mobility systems. More than 16,000 volunteer leaders serve on our Board of Directors and our many other boards, councils and committees. Our technical committees write more new aerospace and automotive engineering standards than any other standards-writing organization in the world. We publish thousands of technical papers and book each year, and leading-edge periodicals and Internet and CD-ROM products too. Our Cooperative Research Program helps facilitate projects that benefit the mobility industry as a whole. Numerous meetings and expositions provide worldwide opportunities to network and share information. We also offer a full complement of professional development activities such as seminars, workshops, and continuing education programs. The meetings and activities of local sections provide an opportunity to network with colleagues near you.

About MEMA

Founded in 1904, MEMA exclusively represents and serves more than 700 North American manufacturers of motor vehicle components, tools and equipment, automotive chemical and related products used in the production, repair, and maintenance of all classes of motor vehicles. MEMA is headquartered in Research Triangle Park, N.C., and has offices in Washington, D.C.; Yokohama, Japan; Brussels, Belgium; Mexico City, Mexico; and Sao Paulo, Brazil. The Original Equipment Suppliers Association (OESA), MEMA’s affiliate association that serves automotive original equipment suppliers exclusively, is located in Troy, Michigan.

About the Brake Manufacturers Council (BMC)

Established in 1973, The Brake Manufacturers Council is dedicated to:

Providing and maintaining, for the mutual benefit of all its members, communications as appropriate with federal, state and local governmental authorities, bodies and agencies, in short, authorities - such as NHTSA - with legislative or regulatory function whose actions may affect automotive brake parts or systems.

Obtaining and disseminating to members information on topics of interest to the brake parts industry.

Conducting any further activities as may be appropriate and for the common benefit of manufacturers of automotive brake parts or systems.

Bibliography

[1]

Society of Automotive Engineers, Inc. SAE BRAKE DYNAMOMETER TEST CODE STANDARDS COMMITTEE. “SAE J2430 issued 1999-08. Dynamometer Effectiveness Characterization for Passenger Cars and Light Duty Truck Brake Friction Products.” Warrendale, PA 15096

[2]

NHTSA. “FMVSS 105 hydraulic and electric brake systems” October 1^st. 1997 edition. Baltimore, MD 21201

[3]

NHTSA. “FMVSS 135 Light vehicles brake systems”. Baltimore, MD 21201

[4]

Brake Manufacturers Council. “Aftermarket Friction Product Effectiveness Characterization Guide”. Research Triangle Park, NC 27709-3966

[5]

Society of Automotive Engineers, Inc. Jim Trainor and others. SAE Technical Paper 2001-01-3120 “SAE J2430 Recommended Practice and its application for Characterizing Aftermarket Brake Friction Material Effectiveness.” Warrendale, PA 15096

[6]

Robert Bosch GmbH, 2000 “Automotive Handbook 5^th Edition”. Postfach 30 02 20, Stuttgart, Germany

[7]

Society of Automotive Engineers, Inc. Rudolph Limpert. “Brake design and safety” Warrendale, PA 15096

Useful web sites for literature or additional information

SAE

MEMA

BMC

NHTSA

Link Engineering Co.

www.linkeng.com

Link Testing Laboratories., Inc.

None Instrument Check 80 km/h Cooling Curve

None Instrument Check
80 km/h Cooling Curve