1、Designation: F 457 04Standard Test Method forSpeed and Distance Calibration of Fifth Wheel EquippedWith Either Analog or Digital Instrumentation1This standard is issued under the fixed designation F 457; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, 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 test method covers the determination of vehiclespeed and cumulative distance tr
3、aveled 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-kilogram) unit
4、s 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 regulatory limi
5、tations prior to use. For specificprecautionary statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2F 538 Terminology Relating to the Characteristics and Per-formance of TiresF 1082 Practice for TiresDetermining Precision for TestMethod Standards3. Terminology3.1 Refer to F 538, Sta
6、ndard Terminology Relating to theCharacteristics and Performance of Tires.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 t
7、he vehicle or the test trailer so that the fifth wheelremains 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
8、 is to be communicated to the vehicle operatorat all 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 a
9、nd distance readout to a known speed and distance.5. 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 f
10、or measurement ofspeed and distance. This test method 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 integri
11、ty to withstand long periods ofsustained operation with 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 b
12、ounce and wheel hop, dueto roadway irregularities, to 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
13、each time the tire isreplaced.6.2 InstrumentationFifth-wheel systems shall beequipped with either analog or digital instrumentation fordetermining wheel rotation. Suitable readouts shall be pro-vided.6.2.1 Analog Instrumentation:1This test method is under the jurisdiction of ASTM Committee F09 on Ti
14、resand is the direct responsibility of Subcommittee F09.10 on Equipment, Facilities,and Calibration.Current edition approved Dec. 1, 2004. Published January 2005. Originallyapproved in 1976. Last previous edition approved in 1999 as F 457 94 (1999).2For referenced ASTM standards, visit the ASTM webs
15、ite, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Stat
16、es.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 shall be continuously proportional to therotational vel
17、ocity 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 changes in speed shall not exceed 0.5 s throughput.Generator
18、 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 and display the output as kilometres per hour(miles per
19、 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. The maximum propagation delay of thefilter/readout comb
20、ination 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 actuated by the fifth wheel with anoutput of at least 31 coun
21、ts 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 the count during testing. Theanalog integration of an
22、 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 produce aperiodic electrical signal whose period is some in
23、teger 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 signals at speedsfrom zero to the maximum speed necessary
24、 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 distance display presentedto the operator shall consist of
25、 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 measuring deviceshall have a capability of a resolution of
26、 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 equipment adjustmentscan be maintained within tolerances st
27、ated 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 of the operator. Theminimum increment of the digital s
28、peed 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 Fifth-wheel assemblies shall be inspected periodically
29、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 to adjacent vehicles.8. Calibration Procedure8.1 Since
30、 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 rather than tire pressure or other mechanicalmeans. Adj
31、ustment 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 Preparation:8.2.1 Install the fifth wheel according to
32、 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 by running at least 8 km (5 miles) at approximately64
33、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 current calibration can be estab-lished and how constan
34、t 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 fifth wheel revolutions should bedeterminable to 60.1 re
35、volution 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 pressure or other mechanical means.Adjustment of tire pres
36、sure 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) maybe used for recalibration. Initial and final tire pressure shouldbe recorded for future reference and calibration verification.F4570428.3.
37、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 vehicle at aconstant speed, 60.8 km/h (0.5 mph), along a straight
38、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) required totraverse this distance with a stopwatch, record fifth wh
39、eeloutput, 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 NationalInstitute of Standards and Technology (NIST). Record t
40、henumber 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 afrequency generator monitored by a frequency counter, input afre
41、quency 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 frequenciesthrough the range expected during the test. Record the resultsfor
42、 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. Repeat 8.3.1.3 until this requirement is met.8.3.1.5 Following
43、 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/h (60.5 mph) or to 1 % of the speed to be used forthe tests,
44、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) certified length. Record the relativeposition of the vehicle and cour
45、se 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 position as at the beginning ofthe course.8.3.2.4 Note the fif
46、th-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 performed (two in eachdirection) with the final calibration factor (F)
47、 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 digitalspeed and distance measurements is determined principally by
48、the 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 speeds.This calibration should be accomplished by adjustment o
49、felectronics 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 distance mode (ifrequired) and reset the display to zero.8.4.1.
