1、Designation: F457 04 (Reapproved 2010)Standard Test Method forSpeed and Distance Calibration of Fifth Wheel EquippedWith Either Analog or Digital Instrumentation1This standard is issued under the fixed designation F457; the number immediately following the designation indicates the year of originala
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of vehiclespeed and cumulat
3、ive distance traveled using a device termeda fifth wheel and using appropriate associated instrumentation.1.2 This test method also describes the calibration techniqueapplicable to digital or analog speed and distance measurementsystems employing a fifth wheel.1.3 The values stated in SI (millimetre
4、-kilogram) units areto be regarded as the standard.1.4 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
5、regulatory limitations prior to use. For specificprecautionary statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2F538 Terminology Relating to the Characteristics and Per-formance of TiresF1082 Practice for TiresDetermining Precision for TestMethod Standards33. Terminology3.1 Refer
6、 to Terminology F538.4. Summary of Test Method4.1 Vehicle speed and distance determinations are made byuse of a fifth wheel, signal transducer(s), and compatibledisplay devices.4.2 The fifth wheel assembly and signal transducer(s) areattached to the vehicle or the test trailer so that the fifth whee
7、lremains in contact with the normal roadway surface while theequipment is in motion. The rotation of this wheel is detectedin a suitable manner and is translated into measurements ofvehicle speed and distance with auxiliary equipment.4.3 The speed is to be communicated to the vehicle operatorat all
8、times, and should be visible without undue distraction ora requirement for physical movement on the part of theoperator.4.4 Fifth wheel calibration is performed by operating thedevice at a fixed speed over a known distance and comparingthe speed and distance readout to a known speed and distance.5.
9、Significance and Use5.1 This test method may be used for calibration of speedand distance measurement systems used on tire test vehiclesand tire test trailers, or any land-based vehicle that contacts theroad and that uses a trailing-wheel system for measurement ofspeed and distance. This test method
10、 applies only to hard, dry,smooth surfaces and is not accurate for highly curved vehiclepaths. This test method does not encompass optical types ofdevices.6. Apparatus6.1 Fifth WheelThe fifth-wheel assembly shall be ofsufficient mechanical integrity to withstand long periods ofsustained operation wi
11、th minimal maintenance. The wheelvertical pivot assembly shall be sufficient to permit directionalchanges without inducing lateral skidding of the fifth-wheeltire. The fifth-wheel assembly shall be equipped with asuspension capable of minimizing bounce and wheel hop, dueto roadway irregularities, to
12、 the extent necessary to ensuremeasurement accuracy. The wheel shall be equipped with asuitable tire, preferably of a straight-ribbed design. The tiresshall have a minimum (new) size of 34937 (16 3 138). Tireand wheel shall be balanced statically each time the tire isreplaced.6.2 InstrumentationFift
13、h-wheel systems shall beequipped with either analog or digital instrumentation fordetermining wheel rotation. Suitable readouts shall be pro-vided.1This test method is under the jurisdiction of ASTM Committee F09 on Tiresand is the direct responsibility of Subcommittee F09.10 on Equipment, Facilitie
14、sand Calibration.Current edition approved Feb. 1, 2010. Published May 2010. Originallyapproved in 1976. Last previous edition approved in 2004 as F457 04. DOI:10.1520/F0457-04R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
15、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, P
16、A 19428-2959, United States.6.2.1 Analog Instrumentation:6.2.1.1 Generator (tachometer)The generator shall becoupled to the fifth wheel to produce an electrical outputproportional to the angular velocity (converted into linearvelocity expressed in km/h (mph) of the fifth wheel. Thegenerator output s
17、hall be continuously proportional to therotational velocity within the required tolerance. The generatoroutput shall be biased after engineering unit conversion by anamount less than or equal to 0.5 % of the converted speed, or0.3 km/h (0.2 mph), whichever is greater. The generatorresponse to change
18、s in speed shall not exceed 0.5 s throughput.Generator operation shall not be degraded by direct or con-densed moisture, road film, petroleum residue, dust, salt, orother environmental contaminates and ambient temperatureextremes.6.2.1.2 Speed ReadoutThe display shall measure the gen-erator output a
19、nd display the output as kilometres per hour(miles per hour). The generator output readout shall beequipped with a low pass active filter that will reduce the rippleoutput of the generator to less than or equal to 1 % of themeasured signal or 0.8 km/h (0.5 mph) peak to peak, which-ever is greater. T
20、he maximum propagation delay of thefilter/readout combination shall not exceed 0.5 s. The readoutshall be biased to an amount less than or equal to 1.0 % of thetrue speed, 0.5 km/h (0.3 mph), whichever is greater.6.2.1.3 Distance ReadoutThe distance measuring deviceshall consist of a counter actuate
21、d by the fifth wheel with anoutput of at least 31 counts per metre (10 counts per foot).Distance traveled is calculated by multiplying the distance perpulse by the number of pulses indicated. The count shall berestorable to zero and possess sufficient digit capacity tominimize the need for recycling
22、 the count during testing. Theanalog integration of an electrical generator signal to yield adistance measurement is not recommended. The distancemeasuring device shall have a capability of a resolution of 8 cm(3 in.).6.2.2 Digital Instrumentation:6.2.2.1 TransducerThe digital transducer shall produ
23、ce aperiodic electrical signal whose period is some integer fractionof the revolution rate of the fifth wheel, and there shall be aminimum of ten signal counts per 0.3 m (1 ft) of travel of thefifth wheel along the vehicle path. The transducer shall becapable of providing the periodic electrical sig
24、nals at speedsfrom zero to the maximum speed necessary for the test beingconducted. Transducer operation shall not be degraded bydirect or condensed moisture, road film, petroleum residue,dust, salt, or other environmental contaminates and ambienttemperature extremes.6.2.2.2 Distance ReadoutThe dist
25、ance display presentedto the operator shall consist of a digital number representingthe distance traveled. The use of analog integration is notrecommended unless equipment adjustments can be main-tained within the tolerances stated below, over the expectedambient temperature range. The distance meas
26、uring deviceshall have a capability of a resolution of 0.076 6 0.038 m (0.256 0.125 ft).6.2.2.3 Speed ReadoutThe speed display device shallconsist of a digital number. The use of analog integration orsuccessive approximation techniques of speed determination,or both, are not recommended unless equip
27、ment adjustmentscan be maintained within tolerances stated below, over theexpected temperature range of the instrumentation environ-ment. The speed readout displays shall be communicated to thevehicle operator at all times without causing undue distractionsor requiring physical movement on the part
28、of the operator. Theminimum increment of the digital speed readout shall be 1km/h, if the readout displays in km/h, or 1 mph, if the readoutdisplays in mph.6.3 Tire Pressure, to be accurate to 3 kPa (0.5 psi).6.4 Stopwatch (required only for analog instrumented fifthwheel).7. Safety Precautions7.1 F
29、ifth-wheel assemblies shall be inspected periodically toassure security of attachment. A safety chain is recommendedto prevent loss under extreme operating conditions. Wheelassemblies should not be subjected to undue side forces, orother conditions that may either impair accuracy or present ahazard
30、to adjacent vehicles.8. Calibration Procedure8.1 Since analog instrumentation measures fifth-wheel an-gular velocity and digital instrumentation measures angulardisplacement, follow different calibration procedures for eachsystem. In either case, accomplish calibration by adjustmentsof electronics r
31、ather than tire pressure or other mechanicalmeans. Adjustment of tire pressure may affect the dynamics ofthe fifth-wheel suspension and may disrupt optimum tire-roadcontact. However, small tire inflation pressure changes lessthan 5 psi may be used for small recalibration adjustments.8.2 Fifth-Wheel
32、Preparation:8.2.1 Install the fifth wheel according to the manufacturersinstructions and as near as possible to the mid-track position ofthe vehicle.8.2.2 Adjust the fifth-wheel tire pressure to the manufactur-ers specification.8.2.3 It is common practice that the fifth wheel be preparedfor testing
33、by running at least 8 km (5 miles) at approximately64 km/h (40 mph) immediately before use. Normal travel inpreparation for calibration fulfills this requirement.8.3 Analog CalibrationThe ultimate accuracy of speedmeasurements is determined principally by the accuracy towhich the speed per volt or c
34、urrent calibration can be estab-lished and how constant this calibration remains over the rangeof speed and over time. The accuracy of the distance measure-ment is dependent primarily upon the accuracy to which thedistance traveled per revolution of the fifth wheel can bedetermined. The number of fi
35、fth wheel revolutions should bedeterminable to 60.1 revolution in 0.8-km (0.5-mile) distance,measured using a device whose calibration is traceable to theNational Institute of Standards and Technology (NIST). Thiscalibration should be accomplished by adjustments of electron-ics rather than tire pres
36、sure or other mechanical means.Adjustment of tire pressure may affect the dynamics of the fifthwheel suspension and may disrupt optimum tire-road contact.However, tire pressure changes of less than 34 kPa (5 psi) mayF457 04 (2010)2be used for recalibration. Initial and final tire pressure shouldbe r
37、ecorded for future reference and calibration verification.8.3.1 Speed Calibration:8.3.1.1 Prepare the fifth wheel in accordance with 8.2.8.3.1.2 Adjust the speed indicator and graphic recordermeter, if necessary, to zero while the vehicle is stationary.8.3.1.3 For analog systems, drive the test vehi
38、cle at aconstant speed, 60.8 km/h (0.5 mph), along a straight testcourse of at least 0.8 km (0.5 miles) measured using a devicewhose calibration is traceable to the National Institute ofStandards and Technology (NIST), at the speed(s) at which tiretests are to be conducted. Measure the time(s) requi
39、red totraverse this distance with a stopwatch, record fifth wheeloutput, and compute vehicle speed(s). For digital systems,drive the test vehicle in accordance with 8.4.1 through a trap ofcalibrated distance of at least 0.8 km (0.5 miles) measuredusing a device whose calibration is traceable to the
40、NationalInstitute of Standards and Technology (NIST). Record thenumber of counts for the distance and repeat four times.Average the runs and compute the number of pulses per secondat 1 km/h if the calibration is being performed in km/h, or 1mph if the calibration is being performed in mph. Using afr
41、equency generator monitored by a frequency counter, input afrequency equivalent to the highest speed expected duringtesting. Adjust the output of the readout or signal conditionerfor engineering conversion to an easily readable display.Repeat this for several (at least five) different frequenciesthr
42、ough the range expected during the test. Record the resultsfor future reference and calibration verification.8.3.1.4 If the speed readout and recorder are not equal to thecomputed speed to within 60.5 km/h (0.3 mph), adjust eitherthe recorder gain or meter gain, or both, to achieve correspon-dence.
43、Repeat 8.3.1.3 until this requirement is met.8.3.1.5 Following compliance with the accuracy require-ment of 8.3.1.4, four additional test runs shall be made (two ineach direction). Compliance with 8.3.1.4 in all four runs shallconstitute a satisfactory speed calibration if the data repeats to60.8 km
44、/h (60.5 mph) or to 1 % of the speed to be used forthe tests, whichever is greater.8.3.2 Distance Calibration:8.3.2.1 Paragraphs 8.2.1-8.2.3 should be followed if thespeed calibration was not performed.8.3.2.2 Position the test vehicle at one end of a test course ofat least 0.8-km (0.5-mile) certifi
45、ed length. Record the relativeposition of the vehicle and course beginning marker.8.3.2.3 After recording the fifth-wheel revolution counterreading, smoothly accelerate the test vehicle to the tire testingspeed and stop smoothly at the other end of the course with theend marker in the same relative
46、position as at the beginning ofthe course.8.3.2.4 Note the fifth-wheel revolution counter reading andcalculate the number of revolutions.8.3.2.5 Calculate the distance calibration factor F as fol-lows:F 5Test course lengthNumber of fifth wheel revolutions8.3.2.6 Four such test runs shall be performe
47、d (two in eachdirection) with the final calibration factor (F) being the averageof the four calculations. Unknown distances may now bemeasured by multiplying the calibration factor (F)bythenumber of fifth-wheel revolutions in the unknown distance.8.4 Digital CalibrationThe ultimate accuracy of digit
48、alspeed and distance measurements is determined principally bythe accuracy to which the distance per pulse is adjusted over acourse of known length. Periodic calibration is required tocompensate for such factors as tire treadwear, tire aging andgrowth, rolling resistance, and temperature at various
49、speeds.This calibration should be accomplished by adjustment ofelectronics rather than tire pressure or other mechanical means.Adjustment of tire pressure may affect the dynamics of thefifth-wheel suspension and disrupt optimum tire-road contactconditions. However, tire inflation pressure changes may beused for small recalibration adjustments. Initial and final tirepressure should be recorded for future reference and calibrationverification.8.4.1 Distance Calibration:8.4.1.1 Prepare the fifth wheel in accordance with 8.2.1-8.2.3.8.4.1.2 Set the instrumentation in the
