[Code of Federal Regulations]

[Title 49, Volume 5]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR325.59]



[Page 15]

 

                        TITLE 49--TRANSPORTATION

 

                      DEPARTMENT OF TRANSPORTATION

 

PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS

--Table of Contents

 

        Subpart E_Measurement of Noise Emissions; Stationary Test

 

Sec. 325.59  Measurement procedure; stationary test.



    In accordance with the rules in this subpart, a measurement shall be 

made of the sound level generated by a stationary motor vehicle as 

follows:

    (a) Park the motor vehicle on the test site as specified in Sec. 

325.53 of this subpart. If the motor vehicle is a combination 

(articulated) vehicle, park the combination so that the longitudinal 

centerlines of the towing vehicle and the towed vehicle or vehicles are 

in substantial alinement.

    (b) Turn off all auxiliary equipment which is installed on the motor 

vehicle and which is designed to operate under normal conditions only 

when the vehicle is operating at a speed of 5 mph (8 kph) or less. 

Examples of such equipment include cranes, asphalt spreaders, liquid or 

slurry pumps, auxiliary air compressors, welders, and trash compactors.

    (c) If the motor vehicle's engine radiator fan drive is equipped 

with a clutch or similar device that automatically either reduces the 

rotational speed of the fan or completely disengages the fan from its 

power source in response to reduced engine cooling loads, park the 

vehicle before testing with its engine running at high idle or any other 

speed the operator may choose, for sufficient time but not more than 10 

minutes, to permit the engine radiator fan to automatically disengage 

when the vehicle's noise emissions are measured under stationary test.

    (d) With the motor vehicle's transmission in neutral and its clutch 

engaged, rapidly accelerate the vehicle's engine from idle to its 

maximum governed speed with wide open throttle. Return the engine's 

speed to idle.

    (e) Observe the maximum reading on the sound level measurement 

system during the time the procedures specified in paragraph (d) of this 

section are followed. Record that reading, if the reading has not been 

influenced by extraneous noise sources such as motor vehicles operating 

on adjacent roadways.

    (f) Repeat the procedures specified in paragraphs (d) and (e) of 

this section until the first two maximum sound level readings that are 

within 2 dB(A) of each other are recorded. Numerically average those two 

maximum sound level readings. When appropriate, correct the average 

figure in accordance with the rules in subpart F of this part.

    (g) The average figure, corrected as appropriate, contained in 

accordance with paragraph (f) of this section, is the sound level 

generated by the motor vehicle for the purpose of determining whether it 

conforms to the Standard for Operation Under Stationary Test, 40 CFR 

202.21. (Table 1 in Sec. 325.7 lists the range of maximum permissible 

sound level readings for various test conditions.)



[40 FR 42437, Sept. 12, 1975, as amended at 41 FR 10226, Mar. 10, 1976]



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