1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J3006_201410 SURFACE VEHICLE RECOMMENDED PRACTICE J3006 OCT2014 Issued 2014-10 Lo
5、w-duty Inertia Dynamometer Hydraulic Brake Wear Test Procedures for Vehicles Above 4536 kg (10 000 lb) of GVWR RATIONALE Certain vehicle applications (like flat-bed recovery vehicles) have driving patterns which are considered light-duty with (a) friction material temperatures remaining under 232.0
6、C (450 F) 2.03 to 2.54 mm (0.08 to 0.1 inch) below the braking surface for at least 90% of the time, and (b) brake applications which require 2690 kPa (390 lbf/in) or less of hydraulic pressure. This Recommended Practice provides two inertia-dynamometer test procedures, which are repeatable and cost
7、-effective to assess, screen, benchmark, troubleshoot, or fingerprint a given foundation brake regarding low-duty brake wear. The first procedure (or Method A) is a wear versus temperature test from 93.0 to 427.0 C (200 to 800 F) to determine if there are potential wear rate issues under low tempera
8、ture conditions and a low-duty driving cycle. If deemed required after the initial wear versus temperature test (Method A), or upon direct customer request, the second procedure (or Method B) provides an extensive wear test at a constant temperature of 79.0 C (175 F) to determine the wear rates and
9、behavior of the friction couple. Data from this Recommended Practice may be combined with other brake system and vehicle characteristics for a comprehensive product characterization program. Since other wear test procedures cover a different (higher) range of operating temperatures, kinetic energies
10、, and levels, the accelerated wear rate behavior of certain friction materials under low-duty regimes is not properly determined or estimated using test conditions which can affect the transfer layer behavior. The wear test method implemented in this Recommended Practice was derived from prior field
11、 testing and correlation investigation. Hence, careful attention was given to not alter the sequence and test conditions which have demonstrated correspondence to the vehicle behavior. The SAE Truck and Bus Hydraulic Brake Committee considers laboratory test procedures useful in supporting harmoniza
12、tion to improve the overall performance, durability, and safety of motor vehicle braking systems using relevant and cost-effective protocols. SAE INTERNATIONAL J3006 Issued OCT2014 Page 2 of 18 TABLE OF CONTENTS 1. SCOPE 3 1.1 Purpose . 3 2. REFERENCES 3 2.1 Related Publications . 3 3. DEFINITIONS .
13、 3 4. TEST CYCLE 6 4.1 Dynamic Brake Application . 6 4.2 Time t0 . 6 4.3 Time t1 . 6 4.4 Time t2 . 6 4.5 Time t3 . 7 4.6 Time t4 . 7 5. TEST EQUIPMENT . 7 6. TEST CONDITIONS . 7 7. TEST PARTS PREPARATION AND TEST SETUP . 8 8. BRAKE DRAG, FLUID DISPLACEMENT, AND BRAKEAWAY TORQUES 12 9. TEST PROCEDURE
14、S . 12 9.1 Low-Duty Wear versus Temperature Test Method A 12 9.2 Low-Duty Wear at Fixed Temperature Test Method B 14 10. TEST REPORT . 15 11. NOTES 16 11.1 Marginal Indicia . 16 APPENDIX A GUIDELINES FOR TARGET WEAR VALUES (INFORMATIVE) . 17 APPENDIX B SAMPLE TABULAR WEAR REPORTS FOR DISC BRAKES UND
15、ER METHOD A 18 FIGURE 1 TYPICAL BRAKE APPLICATION TIME STAMPS . 6 FIGURE 2 COOLING AIR FLOW DIRECTION RELATIVE TO CALIPER POSITION . 8 FIGURE 3 PLUG-TYPE THERMOCOUPLE FOR BRAKE ROTOR 9 FIGURE 5 WEAR MEASUREMENT POSITIONS FOR DRUM BRAKES (A) LEADING SHOE; (B) TRAILING SHOE . 10 TABLE 1 WEAR VERSUS TE
16、MPERATURE TEST SEQUENCE METHOD A 13 TABLE 1 WEAR VERSUS TEMPERATURE TEST SEQUENCE METHOD A (CONTINUED) 14 TABLE 2 FIXED TEMPERATURE WEAR TEST SEQUENCE METHOD B . 14 TABLE 2 FIXED TEMPERATURE WEAR TEST SEQUENCE METHOD B (CONTINUED) 15 SAE INTERNATIONAL J3006 Issued OCT2014 Page 3 of 18 SCOPE This Rec
17、ommended Practice is derived from OEM and tier-1 laboratory tests and applies to two-axle multipurpose passenger vehicles, or trucks with a GVWR above 4536 kg (10 000 pounds) equipped with hydraulic disc or drum service brakes. Before conducting testing for a specific brake sizes or under specific t
18、est conditions, review, agree upon, and document with the test requestor any deviations from the test procedure. Also, the applicable criteria for the final test results and wear rates deemed as significantly different require definition, assessment, and proper documentation; especially as this will
19、 determine whether or not Method B testing is needed. This Recommended Practice does not evaluate or quantify other brake system characteristics such as performance, noise, judder, ABS performance, or braking under extreme temperatures or speeds. Minimum performance requirements are not part of this
20、 recommended practice. Consistency and margin of pass/fail of the minimum requirements related to wear rates and wear behavior can be assessed as part of the project in coordination with the test requestor. NOTE: This Recommended Practice uses the unit conversion and rounding techniques from the NIS
21、T Special Publication 811. This to ensure the use of standard conversion factors and to determine the appropriate number of significant digits to ensure the Rounding Error (RE) of the converted unit is smaller than or similar to the RE of the original English or Imperial unit. Purpose The purpose of
22、 this procedure is to assess wear levels and wear rates at different brake temperatures or at fixed temperature with extended wear cycles during conditions that correspond to low-duty braking using single-ended inertia dynamometer tests. REFERENCES Related Publication The following publication is pr
23、ovided for information purposes only and are not a required part of this SAE Technical Report. 2.1.1 NIST Publications Available from NIST, Gaithersburg, MD 20899, http:/physics.nist.gov/cuu/pdf/sp811.pdf NIST Special Publication 811; 2008 Edition - Guide for the Use of the International System of U
24、nits (SI) Besides internal or proprietary information or requirements, no other publications constitute a required part of this document. DEFINITIONS APPARENT FRICTION FOR DISC BRAKES Per Equation 1: L- 6: ? ; (Eq. 1) where: = apparent friction for disc brakes. unitless SAE INTERNATIONAL J3006 Issue
25、d OCT2014 Page 4 of 18 DRUM BRAKE EFFECTIVENESS (C*) Per Equation 2: %L- : ? ; (Eq. 2) where:*C = effectiveness for drum brakes. unitless T= output torque. Nm, lbft p = brake pressure. kPa, lbf/in Thresholdp= minimum pressure required to start developing braking torque. kPa, lbf/in PA = total piston
26、 area acting on one side of the caliper for disc brakes; total wheel cylinder area for drum brakes mm2, in effR= radial distance from centerline of the piston to the axis of rotation for disc brakes; internal drum diameter divided by 2 for drum brakes, unless other dimensions are provided by the req
27、uestor. mm, in K= Brake efficiency 100 unitless G5= Unit conversion factor; G5= 1x106for SI units; and G5= 12 for English units BRAKE CORNER Assembly of the foundation brake including friction material, caliper or wheel cylinder assembly with mounting hardware, brake rotor or drum, and wheel hub ass
28、embly excluding wheel and tire. BRAKING FORCE DISTRIBUTION Ratio between the braking force of each axle and the total braking force for the vehicle, expressed as a percentage for each axle (e.g. 50% front, 50% rear). For the decelerations of interest in this procedure, the total braking force distri
29、bution between the front and the rear axle is a function of the corresponding brake sizes, tire sizes, and the coefficient of friction (or brake effectiveness for drum brakes). BREAKAWAY AND SUSTAINED ROTATIONAL TORQUE Torque required to initiate brake rotation and measured for one complete revoluti
30、on, measured 30 seconds after releasing any pressure acting on the brake. DECELERATION-CONTROLLED BRAKE APPLICATION Inertia-dynamometer control algorithm which adjusts brake pressure in real time to maintain a constant torque output calculated from the instantaneous deceleration specified in the tes
31、t procedure. PRESSURE-CONTROLLED BRAKE APPLICATION Inertia-dynamometer control algorithm that maintains a constant input pressure to the brake irrespective of the torque output. SAE INTERNATIONAL J3006 Issued OCT2014 Page 5 of 18 TORQUE-CONTROLLED BRAKE APPLICATION Inertia-dynamometer control algori
32、thm which adjusts brake pressure in real time to maintain a constant torque output independently from the instantaneous deceleration. INITIAL BRAKE TEMPERATURE IBT Brake rotor (or drum) temperature at the start of the service brake application. C, F GROSS VEHICLE WEIGHT RATING GVWR Maximum vehicle w
33、eight declared by the vehicle manufacturer. kgf, lbf GROSS AXLE WEIGHT RATING GAWR Maximum axle sprung weight declared by the manufacturer. When multiple axle component ratings are available instead of a unique value for the axle, use the lowest rating declared. kgf, lbf LIGHTLY LOADED VEHICLE WEIGH
34、T LLVW Unloaded vehicle weight plus 227.0 kg (500 lbf) (including driver and test instrumentation). kgf, lbf TIRE DYNAMIC ROLLING RADIUS Equivalent tire radius that generates for a specific tire size the revolutions-per-mile published by the tire manufacturer. Use Equation 3 for SI units and Equatio
35、n 4 for English units. Use the tire dynamic rolling radius to calculate the dynamometer rotational speed for a given linear vehicle speed and the test inertia. SI units 4UJ L5 : 4 = 7 8 86 (Eq. 3)English units 4UJ L: 7 7 : 46 (Eq. 4) where:dynR= tire dynamic rolling radius. mm using Equation 3; in u
36、sing Equation 4 Revolutions Per Mile = tire manufacturer specification for revolutions per mile. Typically shown for the tire size on the manufacturers website WHEEL LOAD Portion of the total vehicle weight braked by the tested corner. Wheel load is a function of the vehicle load condition (LLVW or
37、GVWR) and the brake force distribution per item 3.4. Unless otherwise specified, use 25% of the GVWR. kg, lb TEST INERTIA Mechanical or simulated (electrical) inertia to replicate the rotational energy input as a function of the reflected wheel load braked by the corner and the tire dynamic rolling
38、radius using Equation 5. kgm, lbfft + LG694 6(Eq. 5)SAE INTERNATIONAL J3006 Issued OCT2014 Page 6 of 18 where:+ = test inertia. kgm, slugft G6= unit conversion factor. G6= 1 for SI units. G6= 2.16 x 10-4for English units 9 = wheel load per item 3.14 4 = tire dynamic rolling radius per item 3.13 SNUB
39、 A service brake deceleration from a higher reference speed to a lower reference speed equal to or greater than 5 km/h (3.1 mph). STOP A service brake deceleration from a higher reference speed to a lower reference speed equal to or lower than 0.8 km/h (0.5 mph). TEST CYCLE Dynamic Brake Application
40、 Figure 1 illustrates the main time-stamps used to characterize the brake application. FIGURE 1 TYPICAL BRAKE APPLICATION TIME STAMPS Time t0 Brake application initiation. At this time, the pressure starts to rise. Time t1 Time at level reached. At this time, the brake reaches its target level for d
41、eceleration, pressure, or torque control. At time t1, the calculation of average-by-time and the average-by-distance begins. Time t2 Time at the end of the averages. At time t2, the inertia-dynamometer data acquisition system terminates the calculation of average-by-time and average-by-distance. Tim
42、e t2 is the end of the stable portion of the brake application. t2 is defined as the time at which speed is 0.5 km/h above the release speed (t3). SAE INTERNATIONAL J3006 Issued OCT2014 Page 7 of 18 Time t3 Time at dynamometer release speed. At time t3, the inertia-dynamometer servo controller relea
43、ses the brake. Time t4 Time at brake pressure and torque lost and there is no measurable braking force. At time t4, pressure and torque are below the minimum thresholds. The inertia-dynamometer considers the braking event complete and the foundation brake is fully released. TEST EQUIPMENT Single-end
44、ed brake inertia-dynamometer capable of performing deceleration-, pressure-, and torque-controlled brake applications, and capable to accelerate from zero to 450 revolutions per minute in 60 seconds or less. Automatic data acquisition system capable of recording digitally the following channels at 2
45、00 Hz minimum: 5.1.1 Brake equivalent linear speed. km/h, mph 5.1.2 Brake input pressure. kPa, lbf/in 5.1.3 Brake output torque. Nm, lbfft 5.1.4 Brake fluid displacement, if available. mm3, in Automatic data collection system capable of recording digitally the following channels at 50 Hz minimum: 5.
46、2.1 Brake rotor (or drum) temperature. C, F 5.2.2 Brake pad(s) or brake shoe(s) temperature (optional). C, F 5.2.3 Cooling air temperature (optional). C, F 5.2.4 Cooling air relative humidity (optional). %RH 5.2.5 Cooling air speed or flow. km/h, ft/s, m/min, ft/min Global (continuous) data recordin
47、g for the entire duration of the test (including brake-off operation) at 2 Hz. TEST CONDITIONS Use vehicle-specific hardware and components to fabricate the corresponding brake fixture. The fixture design and mounting on the inertia-dynamometer need to reflect as close as feasible in-service conditi
48、on. Unless otherwise specified, control cooling air temperature to 24.0 to 38.0 C (75 to 100 F) when a cooling air temperature control system is available. Cooling air speed shall be 40 km/h 3.2 km/h (25 mph 2 mph) and directed uniformly and continuously over the brake assembly. Unless otherwise specified by the test requestor, direct the cooling air on
