1、Designation: E1337 90 (Reapproved 2012)Standard Test Method forDetermining Longitudinal Peak Braking Coefficient of PavedSurfaces Using Standard Reference Test Tire1This standard is issued under the fixed designation E1337; the number immediately following the designation indicates the year oforigin
2、al adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of peakbraking coefficien
3、t of paved surfaces using a standard referencetest tire (SRTT) as described in Specification E1136 thatrepresents current technology passenger car radial tires. Gen-eral test procedures and limitations are presented for determin-ing peak braking coefficient independent of surface conditions.Actual s
4、urface test conditions are determined and controlled bythe user at the time of test. Test and surface conditiondocumentation procedures and details are specified. This mea-surement quantifies the peak braking coefficient at the time oftest and does not necessarily represent a maximum or fixedvalue.1
5、.2 This test method utilizes a measurement representingthe peak braking force on a braked test tire passing over a roadsurface. This test is conducted with a tire under a nominalvertical load at a constant speed while its major plane isparallel to its direction of motion and perpendicular to thepave
6、ment.1.3 The measured peak braking coefficient obtained with theequipment and procedures stated herein may not necessarilyagree or correlate directly with those obtained by other surfacecoefficient measuring methods.1.4 The values stated in inch-pound units are to be regardedas standard. The values
7、given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establi
8、sh appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE556 Test Method for Calibrating a Wheel Force or TorqueTransduc
9、er Using a Calibration Platform (User Level)E867 Terminology Relating to Vehicle-Pavement SystemsE1136 Specification for P195/75R14 Radial Standard Refer-ence Test TireF377 Practice for Calibration of Braking/Tractive MeasuringDevices for Testing Tires3F408 Test Method for Tires for Wet Traction in
10、Straight-Ahead Braking, Using a Towed TrailerF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentation3. Terminology3.1 Definitions:3.1.1 chirp testthe progressive application of brake torquerequired to produce the maximum value of longit
11、udinal brak-ing force that will occur prior to wheel lockup, with subsequentbrake release to prevent any wheel lockup (tire slide).3.1.2 For other definitions pertaining to this standard, seeTerminology E867 and Method F408.3.2 Definitions of Terms Specific to This Standard:3.2.1 braking force coeff
12、cient, tirethe ratio of brakingforce to vertical load.3.2.2 braking force coeffcient, tire, peak the maximumvalue, as defined in 12.2, of tire braking force coefficient thatoccurs prior to wheel lockup as the braking torque is progres-sively increased.3.2.3 braking force coeffcient, tire, slide the
13、value of thebraking force coefficient obtained on a locked wheel.3.2.4 braking force, tirethe negative longitudinal forceresulting from braking torque application.1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcom
14、mittee E17.21 onField Methods for Measuring Tire Pavement Friction.Current edition approved Dec. 1, 2012. Published December 2012. Originallyapproved in 1990. Last previous edition approved in 2008 as E1337 90 (2008).DOI: 10.1520/E1337-90R12.2For referenced ASTM standards, visit the ASTM website, ww
15、w.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United S
16、tates13.2.5 braking torquethe negatively directed wheel torque.3.2.6 longitudinal force, tire (Fx) the component of a tireforce vector in the X direction.3.2.7 tire-axis systemthe origin of the tire-axis system isthe center of the tire contact. The X axis is the intersection ofthe wheel plane and th
17、e road plane with a positive directionforward. The Z axis is perpendicular to the road plane with apositive direction downward. The Y axis is in the road plane,its direction being chosen to make the axis system orthogonaland right-hand (see Fig. 1 in Method F408).3.2.8 tire forcesthe external forces
18、 acting on the tire by theroad.3.2.9 torque wheel (T)The external torque applied to a tirefrom a vehicle about the wheel spin axis. Driving torque ispositive wheel torque; braking torque is negative wheel torque.3.2.10 vertical load (Fz)the downward vertical compo-nent of force between the tire and
19、the road.4. Summary of Test Method4.1 The measurements are conducted with a standard refer-ence test tire (Specification E1136) mounted on a test trailertowed by a vehicle. The trailer contains a transducer,instrumentation, and actuation controls for the braking of thetest tire. See 6.6 for trailer
20、instrumentation.4.2 The test apparatus is normally brought to a test speed of40 mph (64 km/h). The brake is progressively applied untilsufficient braking torque results to produce the maximumbraking force that will occur prior to wheel lockup. Longitu-dinal force, vertical load, and vehicle speed ar
21、e recorded withthe aid of suitable instrumentation and data acquisition equip-ment.4.3 The peak braking coefficient of the road surface isdetermined from the ratio of the maximum value of brakingforce to the simultaneous vertical load occurring prior to wheellockup as the braking torque is progressi
22、vely increased.5. Significance and Use5.1 Pavement surfaces have different tractioncharacteristics, depending on many factors. Surface texture,binder content, usage, environmental exposure, and surfaceconditions (that is, wet, dry) are some of the factors.5.2 The measured values represent peak braki
23、ng coefficientsfor tires of the general type in operation on passenger vehicles,obtained with a towed test trailer on a prescribed road surface,under user defined surface conditions. Such surface conditionsmay include the water depth used to wet the road surface andthe type of water application meth
24、od. Variations in theseconditions may influence the test results.6. Apparatus6.1 The apparatus consists of a tow vehicle and test trailer.The vehicle and trailer must comply with all legal requirementsapplicable to state laws when operated on public roads.6.2 Tow VehicleThe vehicle shall have the ca
25、pability ofmaintaining a test speed of 40 mph (64 km/h) within 60.5 mph(60.8 km/h) even at maximum level of application of brakingforces.6.3 Test TrailerThe test wheel shall be equipped with asufficient braking torque to produce the maximum value ofbraking test wheel longitudinal force at the condit
26、ions speci-fied.6.3.1 Each of the trailer wheels shall have a suspensioncapable of holding toe and camber changes to within 60.05with maximum vertical suspension displacements under bothstatic and dynamic conditions.6.3.2 The rate of brake application shall be sufficient tocontrol the time interval
27、between initial brake application andpeak longitudinal force to be between 0.3 and 0.5 s.6.4 Vertical LoadThe trailer shall be of such a design as toprovide a static load of 1031 6 15 lbf (4586 6 67 N) to the testwheel and on detachable trailers a static down load of 100 to200 lbf (445 to 890 N) at
28、the hitch point.6.5 Tire and RimThe test tire shall be the standardreference test tire (SRTT) for pavement tests, as specified inSpecification E1136, mounted on a suitable 14 by 6-in. rim.6.5.1 When irregular wear or damage results from tests, orwhen wear or usage influences the test results, the us
29、e of thetire should be discontinued.6.6 Instrumentation:6.6.1 General Requirements for Measuring SystemTheinstrumentation system shall conform to the following overallrequirements at ambient temperatures between 40 and 100F (4and 38C):6.6.1.1 Overall system accuracy of 61.5 % of applied loadfrom 200
30、 lbf (890 N) to full scale; for example, at 200 lbf (890N), applied calibration force of the system output shall bedeterminable within 63 lbf (613 N).6.6.1.2 The exposed portions of the system shall tolerate100 % relative humidity (rain or spray) and all other adverseconditions, such as dust, shock,
31、 and vibrations which may beencountered in highway operations.6.6.1.3 Braking ForcesThe braking force measuringtransducer shall measure longitudinal reaction force within arange between 0 and 2000 lbf (0 and 8.9 kN) generated at thetire-pavement interface as a result of brake application.The tirefor
32、ce-measuring transducer shall be of such design as tomeasure the tire-pavement interface force with minimuminertial effects. Transducers are recommended to provide anoutput directly proportional to force with hysteresis less than1 % of the applied load, nonlinearity less than 1 % of theapplied load
33、up to the maximum expected loading, andsensitivity to any expected cross-axis loading or torque loadingless than 1 % of the applied load. The force transducer shall bemounted in such a manner as to experience less than 1 angularrotation with respect to its measuring plane at the maximumexpected load
34、ing.6.6.1.4 Vertical LoadThe vertical load measuring trans-ducer shall measure the vertical load at the test wheel duringbrake application. The transducer shall have the same specifi-cations as those described in 6.6.1.3.NOTE 1Other transducer systems may be used to determine peakbraking coefficient
35、s if they can be shown to correlate with the force-measuring transducer system with the same overall accuracy.E1337 90 (2012)26.6.1.5 Vehicle Speed-Measuring TransducersTransducers such as “fifth wheel” or a free-rolling wheelcoupled tachometer shall provide speed resolution and accu-racy of 61.5 %
36、of the indicated speed or 60.5 mph (60.8km/h), whichever is greater. Output shall be directly viewableby the driver and shall be simultaneously recorded. Fifth wheelsystems shall conform to Method F457.6.6.1.6 Signal Conditioning and Data AcquisitionAll sig-nal conditioning and recording equipment s
37、hall provide linearoutput and shall allow data reading resolution to meet therequirements of 6.6.1.1.6.6.1.7 All strain-gage transducers shall be equipped withresistance shunt calibration resistors or equivalent that can beconnected before or after test sequences. The calibration signalshall be at l
38、east 50 % of the normal vertical load and shall berecorded.6.6.1.8 A digital data acquisition system shall be employedto individually digitize the braking force, vertical load, andvehicle speed analog outputs. The braking force, vertical load,and test wheel speed input signals to be digitized shall
39、besampled (as close to simultaneous as possible to minimizephase shifting) at 100 samples per second for each channelfrom unfiltered analog signals. Vehicle speed can be analogfiltered, if necessary, to remove noise since this is a steady-statesignal.NOTE 2Experience indicates that data sampling at
40、100 samples persecond of unfiltered analog skid trailer data will properly describe thesignificant frequencies. To prevent “aliasing,” caution must be exercisedin digitizing skid trailer data which contains any significant frequenciesabove 50 Hz or other types of analog data.7. Hazards7.1 The test v
41、ehicle, as well as all attachments to it, shallcomply with all applicable state and federal laws.All necessaryprecautions shall be taken beyond those imposed by laws andregulations to ensure maximum safety of operating personneland other traffic. No test shall be made when there is dangerthat disper
42、sed water may freeze on the pavement.8. Preparation of Apparatus8.1 Preparation of Test Tire:8.1.1 Trim the test tires to remove all protuberances in thetread area caused by mold air vents or flashes at moldjunctions.8.1.2 Test tires should be stored in such a location that theyall have the same amb
43、ient temperature prior to testing andshield them from the sun to avoid excessive heating by solarradiation.8.1.3 Mount the test tire onTire and RimAssociation (TRA)recommended rim4(6.5) by using conventional mountingmethods. Caution: Assure proper bead seating by the use of asuitable lubricant. Exce
44、ssive use of lubricant should be avoidedto prevent slipping of the tire on the wheel rim.8.1.4 Check the test tires for the specified inflation pressureat ambient temperature (cold), just prior to testing. The test tireinflation pressure shall be 35 6 0.5 psi. (241 6 3 kPa)9. Calibration9.1 Vehicle
45、SpeedCalibrate the test vehicle speed indicatorat the test speed by determining the time for traversing atconstant speed a reasonably level and straight, accuratelymeasured pavement of a length appropriate for the method oftiming. Load the test trailer to its specified operating weight forthis calib
46、ration. Record speed variations during a traverse withthe test system. Make a minimum of three runs at each testspeed to complete the calibration. Other methods of equivalentaccuracy may be used. Calibration of a fifth wheel shall beperformed in accordance with Method F457.10. Conditioning10.1 Prete
47、st Tire Conditioning:10.1.1 Test tire pretest conditioning shall be performed toprecondition all tires prior to initial testing. Pretest condition-ing is to be done only once per tire and prior to any actual testmeasurements. This process is recommended because the newtire burnish effect may have an
48、 influence on the peak brakingcoefficient obtained and to minimize test variability caused bytransient, non-preconditioned, tire braking performance.10.1.2 Pretest tire conditioning shall be conducted on a dryand level surface. Each tire shall be chirped ten times at 20mph (32 km/h) under test load.
49、10.2 General Test Conditions:10.2.1 The test surface shall be free of loose material orforeign deposits.10.2.2 Do not test when wind conditions interfere withwetted test repeatability. Test results may be influenced bywind speed, or direction, or both. The magnitude of thisdependence is a function of the water depth, applicationprocedures, and surface wind protection.11. Procedure11.1 Warm up electronic test equipment as required forstabilization.11.2 Install an SRTT (Specification E1136) in the testposition of the test trailer. A tire with a simila
