1、Designation: E1215 93 (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 revis
2、ion, 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 measur
3、ing 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
4、 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
5、 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
6、: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 St
7、andard: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 S
8、uspension 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 de
9、sign 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).
10、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 ap
11、ply 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 thewe
12、ights 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
13、 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 onMet
14、hods 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
15、 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
16、 C700, West Conshohocken, PA 19428-2959. United States1line 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 hitchconnection
17、s 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, two wheels mounted on a rig
18、id axle, and a towhitch.5.1.1 Suspension SystemThe trailer frame shall be sus-pended on the axle by a system that includes the followingcomponents:5.1.1.1 Horizontal Linkages shall separately constrain theaxle in the longitudinal and lateral directions while allowingfree vertical excursion.5.1.1.2 S
19、pringsTwo coil springs connecting the axle andframe, shall be mounted vertically over the centerline of theaxle. The force constant of each spring shall be 200 6 20lbf/in. (3506 35 N/mm or m). The springs shall be equidistantfrom the longitudinal centerline of the trailer at a distance notless than
20、15 in. (0.38 m).5.1.1.3 Shock AbsorbersTwo shock absorbers, mountedvertically from the axle to the trailer frame, shall be equidistantfrom the longitudinal centerline of the trailer. The ratios of theshock absorbers damping value over12 the sprung mass(2C/MS) shall be in the range of 5.5 to 13 s1wit
21、h a mean valueof 8 s1.4The performance requirement for the damping rate ofthe suspension system in 4.1 may be used as an alternative tothis requirement.5.1.2 Axle and WheelsThe trailer shall have a two-wheelrigid axle in accordance with the following requirements:5.1.2.1 WheelsThe wheels shall be 15
22、 by 6 in. rims.Radial run-out at the bead seats of the wheels when installed onthe axle shall be less than 0.01 in. (0.25 mm) peak-to-peak. Therim shall be marked to indicate the “low-point for matchingwith the tire. The low-point is established by determining thepoints of minimum radius on each bea
23、d seat and locating thelow-point intermediately between those points in proportion totheir relative magnitudes.5.1.2.2 TiresThe tires shall be size P215/75R15, orequivalent, or Specification E1136, and shall meet the GMTPCSpecification.3Before operation, set the tire inflation pressureat the tire ma
24、nufacturers maximum recommended pressure forsize and type of tire used at ambient temperature.5.1.2.3 Optional AlternativeIf the equipment given in4.2.1 is used, the dial indicators are placed close to the tires tomeasure axle-to-road displacement. The tire pressure is ad-justed to give a116 in. (1.
25、6 mm) vertical displacement when200 lbf (890 N) is used rather than the manufacturersmaximum recommended pressure.5.1.2.4 Tire-Wheel AssemblyThe tires shall be mounted onthe wheels so that the painted dot indicating peak tire runoutreaches the low-point mark on the wheel. The tire-wheelassemblies sh
26、all be balanced within 8.0 in./oz (0.58 cm/kg).5.1.2.5 Wheel TrackThe lateral distance between the cen-ter planes of the two tires shall be 68 6 5 in. (1.73 6 0.13 m).5.1.3 Tow HitchA ball-type hitch receptacle shall bemounted at the forward end of the frame on the longitudinalcenterline of the trai
27、ler.NOTE 1The towing vehicle must have power enough to pull the trailerat whatever uniform velocity is specified, even up 6 % grades, and mustbe in good operating condition, particularly its shock absorbers.5.1.3.1 WheelbaseThe trailer shall be designed so that thelongitudinal distance between the c
28、enter of the ball-hitch andthe centerline of the axle shall be 120 6 1 in. (3.05 6 0.03 m).5.1.4 Total MassThe mass of the fully assembled trailershall be 1660 6 50 lbm (753 6 23 kg), and it shall bedistributed so that the ground load at each of the wheels will be780 6 20 lbf (3470 6 89 N), and the
29、hitch load shall be 1006 10 lbf (445 6 44 N). The center of percussion in the verticalplane shall be located as near to the axle as possible.5.1.5 Unsprung MassThe total mass of the axle, wheels,and tires, together with that of the suspension system, shall be320 6 30 lbm (145 6 14 kg).5.1.6 Sprung M
30、assshall normally be 1340 lbm (608 kg).NOTE 2The ratio of the unsprung mass to the sprung mass (Mu/Ms)ishigher than many automobiles.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standar
31、d are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif
32、not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, whic
33、h you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,Un
34、ited States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E17-1002.E1215 93 (2012)2
