ASTM_F_377_-_03_2015.pdf

Designation:F37703(Reapproved 2015)Standard Practice forCalibration of Braking/Tractive Measuring Devices forTesting Tires1This standard is issued under the fixed designation F377;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice gives procedures for the calibration of:reference load cellscalibration platform systems by using a reference load cellstatic calibration of braking/tractive force on locked wheelsof tire test trailers,instrumented vehicles,and laboratory tiretesting machines by using the calibration platform system as acalibration fixture.1.2 The values stated in SI units are to be regarded asstandard.The values in parentheses are for information only.1.3 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:2E74 Practice of Calibration of Force-Measuring Instrumentsfor Verifying the Force Indication of Testing MachinesF538 Terminology Relating to the Characteristics and Per-formance of Tires3.Terminology3.1 Definitions:3.1.1 bias,nthe difference between the average measuredtest result and the accepted reference value;it measures in aninverse manner the accuracy of a test.3.1.2 longitudinal force,F,of a tire,nthe component ofthe tire force vector in the X direction.3.1.3 vertical load,nthe normal reaction of the tire on theroad which is equal to the negative of normal force.4.Summary of Practice4.1 Reference-load cells shall be calibrated using proce-dures and equipment traceable to the National Institute ofStandards and Technology(NIST),or appropriate nationalstandards organization.NOTE1Practice E74 may be used as an alternative method forload-cell calibration.4.2 The calibrated reference-load cell is used to calibrate thecalibration-platform systems or used as the longitudinal forcesensor.The tire test trailer,instrumented vehicle,or laboratorytire testing machine is calibrated with the platform.5.Significance and Use5.1 Calibration is essential in the use of various test plat-forms and devices to insure that the test results generated bythese test devices are accurate,repeatable and meaningful.Thisstandard gives the necessary instructions for the calibration ofall of the test devices cited in the Scope.6.Apparatus6.1 The calibration system consists of the following basiccomponents:6.1.1 PlatformThe platform on which the test wheel isplaced shall have a flat high friction top surface.The platformshall be of sufficient dimensions to support the entire tirecontact patch throughout the calibration process.Alow frictionbearing(an air bearing is recommended)permitting freehorizontal motion and capable of sustaining a vertical loadequal to the largest anticipated wheel load shall support theplatform.The longitudinal movement shall be sufficient toobtain the necessary required force levels.The platform mayalso be instrumented with integrated transducers(Force Sen-sors)to measure vertical and longitudinal forces.6.1.2 Force Generation ApparatusA system,capable ofdeveloping a longitudinal force sufficient for the calibration ofthe operating range of the device,shall be used.The force shallbe applied along the longitudinal centerline of the platform.6.1.3 Force SensorsSensors to measure applied forces inthe vertical and longitudinal directions that shall be used tocalibrate braking/tractive measuring devices.These sensorscan be integrated force transducers located in the platform,scales or tension load cells.Sensors shall have sufficient1This practice is under the jurisdiction of ASTM Committee F09 on Tires and isthe direct responsibility of Subcommittee F09.10 on Equipment,Facilities andCalibration.Current edition approved June 1,2015.Published September 2015.Originallyapproved in 1974.Last previous edition approved in 2009 as F377 03(2009).DOI:10.1520/F0377-03R15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 measurement range to cover the maximum anticipated testwheel forces.Sensors shall be mounted in a manner such thatcross-axis forces will not adversely affect the accuracy.Theforce sensor instrumentation shall have the capability to allowfor the recording of data,such as a chart recorder,data logger,or visual output that allows for manual logging of data.6.1.4 Reference Load CellThe forc