1、Designation: E 1215 93 (Reapproved 2003)Standard Specification forTrailers Used for Measuring Vehicular Response to RoadRoughness1This standard is issued under the fixed designation E 1215; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This document covers the design, performance, andoperating features of a trailer used for measurin
3、g 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 m
4、ovements of thetrailer is not covered in this specification. One example ofinstrumentation is described in Test Methods E 1082.1.4 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、E 1082 Test Method for Measurement of Vehicular Re-sponse to Traveled Surface Roughness2E 1136 Specification for a Radial Reference Test Tire22.2 Other Document:A4082 TPC Tire Performance Criteria, Procedures andSpecifications33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 sp
7、rung 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 Syste
8、mThe 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 requiremen
9、ts 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 require
10、d.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
11、 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
12、 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 s
13、lope ofthe upward (loading) and downward (unloading) data points,ignoring the initial data point if necessary. The slope of thatline is the spring rate and must fall within the range of 180 to220 lbf/in. (32 to 39 N/mm).4.3 Legal Requirements:1This specification is under the jurisdiction of ASTM Com
14、mittee E17 onVehicle-Pavement Systems and is the direct responsibility of Subcommittee E17.31on Methods for Measuring Profile and Roughness.Current edition approved July 15, 1993. Published November 1993. Originallyapproved in 1987. Last previous edition approved in 1990 as E 1215 90.2Annual Book of
15、 ASTM Standards, Vol 04.03.3Available from General Motors Engineering Staff, GM Proving Ground,Milford, MI 48042.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3.1 The vehicle and trailer shall comply with all appli-cable state an
16、d 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 consi
17、st of a rigid framesuspension, two wheels mounted on a rigid 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
18、directions while allowingfree vertical excursion.5.1.1.2 SpringsTwo 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 longitud
19、inal centerline of the trailer at a distance notless than 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 s
20、prung mass(2C/MS) shall be in the range of 5.5 to 13 s1with a mean valueof8s1.4The 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 fol
21、lowing requirements:5.1.2.1 WheelsThe wheels shall be 15 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 establishe
22、d by determining thepoints of minimum radius on each bead 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 E 1136, and shall meet the GMTPC Specification.3Befor
23、e operation, set the tire inflationpressure at the tire manufacturers maximum recommendedpressure for size 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 displac
24、ement. The tire pressure is ad-justed to give a116 in. (1.6 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 mountedon the wheels so that the painted dot indicating peak tire runoutreaches th
25、e low-point mark on the wheel. The tire-wheelassemblies shall 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
26、end of the frame on the longitudinalcenterline of the trailer.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
27、be designed so that thelongitudinal distance between the center 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
28、 of the wheels will be780 6 20 lbf (3470 6 89 N), and the 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
29、 system, shall be320 6 30 lbm (145 6 14 kg).5.1.6 Sprung Massshall 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
30、 any item mentionedin this standard. Users of this standard 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 techni
31、cal committee and must be reviewed every five years andif 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 consideratio
32、n at a meeting of theresponsible technical committee, which 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 Harb
33、or Drive, PO Box C700, West Conshohocken, PA 19428-2959,United 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).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: E-17-1002.E 1215 93 (2003)2
