Document ID: chunk:federal_register_of_legislation:F2021C00509:front:0:p27
Version: federal_register_of_legislation:F2021C00509
Segment Type: other
Provision Reference: 
Character Range: 80002–82906

close when this pressure does not differ by more than 10 %from its stabilized value with the valve open.

           1.3.4. The time-delay switch shall be set for the duration of gas exhaust resulting from the provisions laid down in paragraph 1.3.3 above.

           1.3.5. Engine speed must be 75 % of the speed (S) at which the engine develops maximum power.

           1.3.6. The power indicated by the dynamometer must be 50 % of the full-throttle power measured at 75 % of engine speed (S).

           1.3.7. Any drainholes must be closed off during the test.

           1.3.8. The entire test must be completed within 48 hours.
            If necessary, one cooling period will be observed after each hour.
           Annex 5 – Appendix

         Figure 3. Test apparatus for conditioning by pulsation

    1. Inlet flange or sleeve for connection to the rear of the test exhaust system.
    2. Hand-operated regulating valve.
         3. Compensating reservoir with a maximum capacity of 40 1 and filling time of not less than one second.
    4. Pressure switch with an operating range of 0.05 to 2.5 bar.
    5. Time delay switch.
    6. Pulse counter.
         7. Quick-acting valve, such as exhaust brake valve 60 mm in diameter, operated by a pneumatic cylinder with an output of 120 N at 4 bar. The response time, both when opening and closing, must not exceed 0.5 second.
    8. Exhaust gas evacuation.
    9. Flexible pipe.
         10. Pressure gauge.
           Annex 6

           COMPRESSED AIR NOISE

           1. Method of Measurement

            The measurement is performed at microphone positions 2 and 6 according to Figure 1, with the vehicle stationary . The highest A-weighted noise level is registered during venting the pressure regulator and during ventilating after the use of both the service and parking brakes.
            The noise during venting the pressure regulator is measured with the engine at idling speed. The ventilating noise is registered while operating the service and parking brakes; before each measurement, the air-compressor unit has to be brought up to the highest permissible operating pressure, and then the engine switched off.

           2. Evaluation of the results

            For all microphone positions two measurements are taken. In order to compensate for inaccuracies of the measuring equipment, the meter reading is reduced by 1 dB(A), and the reduced value is taken as the results of measurement. The results are taken as valid if the difference between the measurements at one microphone position does not exceed 2 dB(A). The highest value measured is taken as the results. If this value exceeds the noise limit by 1 dB(A), two additional measurements are to be taken at the corresponding microphone position. In this case, three out of the four results of measurement obtained at this position have to comply with the noise