ASTM_E_1337_-_90_2012.pdf

Designation:E133790(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 oforiginal 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 coefficient 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 surface 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.1.2 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 thepavement.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 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 establish 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 TorqueTransducer 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 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 longitudinal 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 coeffcient,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 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 Subcommittee 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,www.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 States1 3.2.5 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 the 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 F40