ASTM_E_1215_-_93_2012.pdf

Designation:E121593(Reapproved 2012)Standard Specification forTrailers Used for Measuring Vehicular Response to RoadRoughness1This standard is issued under the fixed designation E1215;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 specification covers the design,performance,andoperating features of a trailer used for measuring response toroad roughness.1.2 The specified trailer is a two-wheeled,single-axle ve-hicle that is towed on highways at typical traffic speeds whilethe relative movement between the axle and body is transducedand recorded as an indication of road roughness.1.3 The instrumentation for sensing the movements of thetrailer is not covered in this specification.One example ofinstrumentation is described in Test Methods E1082.1.4 The values stated in inch-pound units are to be regardedas the standard.1.5 The following caveat pertains only to Section 5 of thisspecification:This standard does not purport to address all ofthe safety 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:2E1082 Test Method for Measurement of Vehicular Responseto Traveled Surface RoughnessE1136 Specification for P195/75R14 Radial Standard Refer-ence Test Tire2.2 Other Document:A4082 TPC Tire Performance Criteria,Procedures andSpecifications33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 sprung massthe total mass minus the unsprungmass.3.1.2 suspension deflectionthe change in the vertical dis-tance between the axle at its centerline and a hypotheticalreference line directly above the axle centerline on the rigidframe structure.4.Other Requirements4.1 Damping Ratio of Suspension SystemThe dampingratio of the suspension system on the assembled trailer shall beevaluated by measuring the accumulated suspension movementon the trailer as it is towed over a known or standard calibrationtest surface.It must be verified that it meets one of theacceptance criteria.3The design requirements for the shockabsorbers(5.1.1.3)may be used as an alternative to thisrequirement.4.2 Spring RateThe spring force constant(spring rate)ofthe assembled suspension shall be measured as follows:4.2.1 Apparatus:4.2.1.1 Dial Indicators,with a nominal accuracy of 0.001in.(0.025 mm).Two are required.4.2.1.2 Loading Weights,permitting load increments ofapproximately 20 lbf(89 N)are required.4.2.2 ProcedureMeasure the vertical deflections of thesuspension by placing the dial indicators at points proximate tothe coil springs.With the trailer parked on a level surface,gently apply the weights,in approximately 20-lbf(89-N)increments,on the longitudinal centerline of the trailer directlyabove the centerline of the axle while recording the suspensiondeflection values observed on each dial indicator.Take care notto jar the trailer when applying the weights.Once all theweights have been applied up to the total mass,remove them inthe same manner while recording the deflection measurementsat each increment.4.2.3 Data ReductionSeparately plot the load-deflectionvalues for each suspension system(left and right)on rectilineargraph paper.Draw a straight line that best reflects the slope ofthe upward(loading)and downward(unloading)data points,ignoring the initial data point if necessary.The slope of that1This specification is under the jurisdiction ofASTM Committee E17 on Vehicle-Pavement Systems and is the direct responsibility of Subcommittee E17.31 onMethods for Measuring Profile and Roughness.Current edition approved Dec.1,2012.Published December 2012.Originallyapproved in 1987.Last previous edition approved in 2007 as E1215 90(2007).DOI:10.1520/E1215-93R12.2For 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.3Available from General Motors Engineering Staff,GM Proving Ground,Milford,MI 48042.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 line is the spring rate and must fall within the range of 180 to220 lbf/in.(32 to 39 N/mm).4.3 Legal Requirements:4.3.1 The vehicle and trailer shall comply with all appli-cable state and federal laws,including those related to hitchconnections and lighting of towed vehicles.4.3.2 Reasonable precautions shall be taken beyond thoseimposed by laws and regulations to ensure maximum safety ofoperating personnel and other traffic.5.Design Requirements5.1 ChassisThe chassis shall consist of a rigid framesuspension