1、Designation: E2793 10Standard Guide for theEvaluation, Calibration, and Correlation of E274 FrictionMeasurement Systems and Equipment1This standard is issued under the fixed designation E2793; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 guide describes the evaluation, calibration, andcorrelation of Test Method E274 friction me
3、asurement systemsas conducted at a Field Test Center (FTC)2. The evaluation,calibration and correlation process; using the specializedequipment, facilities, surfaces, trained personnel, and AreaReference Friction Measurement Systems (ARFMS) availableat each FTC; are conducted using the procedures de
4、scribedbelow.1.2 The FTC complies with the requirements of GuideE1890. Guide E1890 requires a more stringent calibrationprocess and requires all ARFMS system be correlated togetheronce a year on three surfaces at three speeds with twelverepeats each for a total of 108 pairs.1.3 This guide is offered
5、 as a process to identify andquantify the variables that affect system performance, tominimize the effect of these variables, and to provide a meansto relate Test Method E274 friction measurement systems toreference skid measurement systems.1.4 The values stated in inch-pound units are to be regarde
6、das 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
7、 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:3E274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE501 Specification for Rib Tire for Pav
8、ement Skid-Resistance TestsE556 Test Method for Calibrating a Wheel Force or TorqueTransducer Using a Calibration Platform (User Level)E867 Terminology Relating to Vehicle-Pavement SystemsE1890 Guide for Validating New Area Reference SkidMeasurement Systems and EquipmentF377 Practice for Calibration
9、 of Braking/Tractive Measur-ing Devices for Testing TiresF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentation3. Terminology3.1 Definitions:3.1.1 Area Reference Friction Measurement System(ARFMS), na Test Method E274 type measurement
10、systemthat meets the requirements of Guide E1890.3.1.2 Calibration Platform, na frictionless moving plat-form for applying a tractive force in the contact plane of a tire,and associated means for measuring the applied horizontal andvertical force. Also referred to as a “force plate.”3.1.3 Field Test
11、 Center (FTC), na facility with the neededtest equipment, Area Reference Friction Measurement System,test pavements and expertise to evaluate, calibrate and corre-late Test Method E274 skid measurement systems.3.2 Other terminology used in this guide conforms to thedefinitions in Terminology E8671Th
12、is guide is under the jurisdiction of ASTM Committee E17 on Vehicle -Pavement Systems and is the direct responsibility of Subcommittee E17.21 on FieldMethods for Measuring Tire Pavement Friction.Current edition approved Dec. 1, 2010. Published December 2010. DOI:10.1520/E2793102Currently, one FTC is
13、 located at Texas Transportation Institute (TTI) nearCollege Station, Texas. A similar Center is located among the facilities of theTransportation Research Center Inc. (TRC) in East Liberty, Ohio3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
14、serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Guide4.1 There are three phases to th
15、is guide. Phase one recordsand reports the static and dynamic condition and accuracy ofthe visiting system in an “as arrived” condition with nochanges being made. During phase two, each subsystem isevaluated and if necessary, adjusted to insure compliance withtolerances outlined in Test Method E274.
16、 Phase three is thefinal dynamic correlation between the visiting system and theARFMS.4.2 An additional service of the FTC will be to calibrate thecalibration platform or force plate used by the visiting agency.4.3 A detailed report will be generated and presented to thevisiting agency describing al
17、l static and dynamic test results.5. Significance and Use5.1 Friction characteristics of road surfaces are monitoredby friction measurement systems, and the operating procedurefor the use of these systems is found in Test Method E274.However, mechanical or electronic system anomalies, overtime, coul
18、d result in measurement errors or inaccuracies. Thisrequires that each of these systems be evaluated, calibrated andcorrelated on a regular basis.5.2 This guide defines the process of ensuring that TestMethod E274 systems produce consistent and accurate dataand correlating the Test Method E274 syste
19、ms to nationalbenchmark Test Method E274 systems.6. Apparatus6.1 Area Reference Friction Measurement System(ARFMS), a Test Method E274 type measurement system thatmeets the requirements of Guide E1890.6.2 Three Test Pavements (pads), with an asphalt, concreteor seal coat surface having a uniform low
20、, medium, and highfriction that spans the typical operating range and used tocorrelate multiple Test Method E274 systems. Similar macrotexture, of the pads, should be avoided. A recommended rangeof SN40R for the low friction pad to be below 30, the mediumfriction pad between 30 and 50 and the high f
21、riction pad above50. The length and width shall be suitable for the entirewater/lockup cycle of Test Method E274 systems at the highestdesignated test speed. The test surfaces shall be homogeneous,level, and free of contaminants and traffic. A nonpolishingsurface is recommended. A suggested length a
22、nd width is 400ft (122 m) by 12 ft (4 m).6.3 Two Load Cells, calibrated annually and National Insti-tute of Science and Technology (NIST) traceable, 1000 lb(4448 N) and 2000 lb (8900 N). Accuracy is required inaccordance with Practice F377.6.4 Two Calibration Platforms, with digital instrumentationa
23、s described in Test Method E556 and have been calibrated inaccordance with Practice F377. The top surfaces of theplatforms are to be installed at the same height as thesurrounding floor.6.5 Two Air Jacks, for lifting each test wheel.6.6 Voltmeter, Oscilloscope, Strain Indicator, and other testinstru
24、ments capable of accurate measurement of voltages, andsignals common in strain gauge instrumentation.6.7 Water Volume Measurement System, to calibrate thewater pumping ability of the water system. Consists of: acollector to capture all water pumped during a fixed timeinterval, a device to measure th
25、e volume of water pumped, anda stopwatch.6.8 Static Water Distribution gauge (SDG), a collector, setat floor level, which is divided into twenty-two sections ofequal width, 58 in. (16 mm), so that each section catches waterfrom the water nozzle and feeds it into a separate reservoir andviewing tubes
26、 thus allowing the water nozzle distribution to beevaluated and photographed.6.9 Speed Measurement System, to measure vehicle speed,60.1 mph (0.2 km/h). A fifth wheel calibrated to Test MethodF457, precision GPS or precision radar is recommended.6.10 Precision Pressure Gauge, and air system for thec
27、alibration of tire pressure gauges. Accuracy of 60.25 % fullscale or better.6.11 Inclinometer, with a measuring resolution of 1 min.6.12 Force Plate Calibration Fixture, a system, capable ofdeveloping a precision longitudinal and vertical force sufficientfor the calibration of a calibration platform
28、 throughout itsoperating range as described in Practice F377.NOTE 1The following procedures (Sections 7, 8, 9 and 14) are for onetest wheel, usually the left. On systems using two test wheels, theseprocedures must be repeated for the opposite side.7. As Arrived Correlation7.1 Visiting systems, upon
29、arrival, will be correlated withthe FTC ARFMS on three surfaces at the systems normal testspeed and optionally at one to two additional test speeds (seeNote 2), with twelve repeats each. This will be done with eithera Specification E501 or Test Method E556 test tire on eachsystem as requested by the
30、 visiting personnel. The visitingsystem and theARFMS should attempt to measure in the samelateral and longitudinal location for each pair of skids. Thetwelve repeats will be averaged and the mean and standarddeviation will be reported, for each system, for each of thethree surfaces. These values wil
31、l be referred to as the “AsArrived Correlation Data.”8. Physical Measurements8.1 Physical measurements of the visiting system will beconducted and recorded in the as arrived condition, beforeany changes are made. These measurements consist of: waternozzle height, horizontal angle, and lateral positi
32、on relative totire centerline, for each nozzle used.Also the distance from thecenter of the hitch ball to the floor, distance from the end of thenozzle to the trailer axle center, distance from the trailer axlecenter to the floor and the distance from the center of the hitchto the center of the trai
33、ler axle will be recorded.8.2 Angle of the trailer tongue and direction (up or down)along with the trailer lean angle will be recorded.8.3 Hitch height, above ground level, versus water load ismeasured and recorded at a full tank of water, a half tank andan empty tank.8.4 The angular rotation of the
34、 force transducer(s) shallexperience less than 1 degree angular rotation with respect toits measuring plane. This may be measured on the calibrationplatform, during the Static Force Evaluation and Calibration,E2793 102using a precision inclinometer attached to the test wheel andoperating the platfor
35、m from 0 to 800 lb (0 to 362 kg) horizontalforce.8.5 Any changes to these measurements, to comply withTest Method E274, are to be made and recorded as “Final.”9. Static Force Evaluation and Calibration9.1 Determine that the calibration platform has been suit-ably calibrated within a one year in acco
36、rdance with PracticeF377.9.2 Drain or fill the water tank to obtain one-half tank ofwater onboard the friction measurement system truck.9.3 Back the trailer onto the calibration platforms ensuringit is square and centered.9.4 Set truck tire, trailer tire and air shock pressures to userspecified pres
37、sures (trailer tires are always set to 24 psi (1.65bars).9.5 Separate trailer from truck and install the tongue loadcell fixture under the trailer hitch.9.6 With both platforms floating, weigh and record the “AsArrived” weight of each wheel and the tongue weight. Anychanges to these weights, after t
38、he “As Arrived” data runs, arerecorded as “Final.”9.7 Reconnect truck and trailer and check trailer alignment.9.8 Apply external air and power to skid system.9.9 Start the truck data system and go to the bridge forcesscreen.9.10 Record the as arrived calibration values (for example:bias, zero, gain,
39、 shunt, or static) for the horizontal force andvertical force channels.9.11 Make an “As Arrived” run, with the plate floating andthe brake locked, from 0 to 800 lb (0 to 362 kg) in 100 lb (45kg) steps recording horizontal and vertical force from platformand horizontal and vertical force from truck d
40、ata system as wellas skid number if available.9.12 Adjust the truck data system to read forces directly andaccurately from the wheel transducer with no computer cor-rection, that is, reset the computer to a gain of 1 and offset ofzero.9.13 Set zero and span on the friction system vertical andhorizon
41、tal force channels, if necessary, to match the calibrationplatform values at zero and 500 lb (226 kg) horizontal and zeroand full vertical force vertical.9.14 Measure horizontal force-into-vertical force cross talkby first recording vertical force on test wheel and plate withzero horizontal force ap
42、plied then lock the brake and pull 500lb (226 kg) horizontal force. Compare the difference in verticalforce value on the platform to the difference in vertical forcevalue from the test wheel transducer. The difference betweenthe change in the transducer force and platform force should beless than 1
43、% or 5 lbs (2.2 kg). If not, rotate the wheeltransducer or adjust the hitch height, within manufactureslimits.9.15 With zero horizontal force applied, measure thevertical-into-horizontal cross talk by first recording the wheeltransducer horizontal force at full vertical force (approximately1085 lb (
44、492 kg) then reduce the wheel weight by 500 lb (226kg) and record wheel horizontal force again. The differencebetween two horizontal force values should be less than 5 lb(2.2 kg). If not, rotate the wheel transducer or adjust the hitchheight slightly, within manufactures limits.9.16 If any mechanica
45、l changes were made, repeat steps9.13, 9.14 and 9.15 until both axes exhibit a cross talk less than1 %. Record the changes and new values.9.17 With additional weights on the test wheel fender,evaluate the vertical force transducer with emphasis on therange from 1250 to 800 lb (566 kg to 362 kg). Mak
46、e three runs,in steps of approximately 50 lb (23 kg), or less, with an air jackunder the test wheel axle, recording platform and systemvertical force, with the last run being in the opposite direction,800 to 1250 lb (362 to 566 kg), to check for hysteresis whichshould be less than1%oftheapplied load
47、. Nonlinearityshould be less than1%oftheapplied load.9.18 Using the air bearing platform, calibrate the frictionmeasurement system vertical and horizontal force channels inaccordance with the manufacturers instructions.9.19 Make three “Final” runs, with the plate floating and thebrake locked. Two fr
48、om zero to 800 lb (362 kg) in 100 lb (45kg) steps and one from 800 lb (362 kg) to zero, recordinghorizontal and vertical force from platform and horizontal andvertical force from truck data system at each step as well asskid number if available9.20 Test Method E274 recommends overall system accu-rac
49、y (applied vs. measured SN) be 1 % of reading from 200lb (91 kg), horizontal force, to full scale. If the calibrationprocess indicates the system is outside these recommendationsremedial action should be taken.9.21 When finished, save the calibration values developedin the system computer. Record the horizontal and verticalforce calibration shunt and other computed constants.9.22 Print out the computer cycle time. Verify with graphi-cal run data, if available or physical observation of eventsduring the final correlation.10. Tire Pressure gauge Calibration10.1 Using the
