GB/T 3871.8-1993 Test methods for agricultural wheeled and tracked tractors Part 8: Noise measurement GB/T3871.8-1993 Standard download decompression password: www.bzxz.net

UDC531.371 629.114.2
National Standard of the People's Republic of China
GB/T 3871. 1~3871. 1293
Test methods for agricultural wheeled and track tractorsTest methods for agricultural wheeled and track tractors1993-03-03 Issued
1993.10-01 Issued
National Standard of the People's Republic of China
Test methods for agricultural wheeled and track tractorsPart 8: Noise measurement
Test methods for agricultural wheeled and track tractorsPurt BMeasurements of noise
GBT 3971.8 93
Generation police H8-
This standard refers to [5] 5131-1982 Yilin tractor and chain conveyor noise measurement. 1 Main content and applicability
This standard specifies the method for measuring the noise of agricultural wheeled and belted tractors. This standard is applicable to agricultural wheeled and belted tractors. 2 Reference standards
GB6235 Agricultural tractor seat marking points GB/T3871.1 Agricultural wheeled and belt tractors test methods Part 1 General requirements 3 Test instruments and equipment and recommended measurement accuracy 3.1 Test equipment
mainly includes: precision sound level meter, dynamometer, load car, tachometer, five-wheel instrument, counter, gauge, durometer and steel tape measure. 3.2 Most measurement accuracy
should meet the following requirements: force ±1.0%. Degree ±0.5%, speed U.5%, speed ±3.C%, noise level ±0.5dB(A), etc. 4 Test items
4.1 The general requirements for the technical condition and environmental test of the test tractor should comply with the relevant provisions of GB/T3871.1. 2.2 The test site is a quiet, open, horizontal site (with a slope of no more than 0.5). The site should be able to ensure that the difference in the hemispherical propagation of sound between the noise source and the microphone is no more than 1A (A). A site that meets the above requirements can be such a site: within a radius of no less than 50m from the center of the test site, there are no buildings, walls, old roads and other obvious sources of sound waves. 1.3 The runway of the test site should be a clean, dry, straight road with a length of no less than 15m. For wheeled ground vehicles, the road surface should be filtered concrete or bluestone; for belt trailers, it should be compressed soil. 4.4 The length of the test site should not be less than 10m. The surface should be made of mixed poles or other hard materials. There should be no noise, noise and high sound absorbing materials on the surface. 4.5 The ambient temperature of the test site is - 530℃, 1.2% above sea level. The wind speed is not more than 5m/6. When the wind speed is greater than 1m/s, in order to avoid the influence of wind noise, the microphone should be covered with a windshield, but it shall not affect the accuracy of the measurement. 4.6 The tractor under test is not equipped with a gear, and the noise (including wind noise) during measurement should be at least 1dB lower than the total noise (A National Supervision and Administration Commission approved on March 3, 1993 and implemented on October 1, 1993). Cn/T3871.B93 48. The sound level meter should be tested at a distance of less than 1dB. There should be no people in the place where the sound level meter is tested. When the noise is in the driving operating position, no other people are allowed in the driving room except the driver. 4.9 Before and after each measurement, use A sound level meter is calibrated with a sound source of 25~-]05011z and a sound level within 0.5dB (4). If the difference between the two is greater than 1H (A), the test is invalid and the test is repeated. 5 Test methodWww.bzxZ.net
5. Dynamic environmental noise measurement (only for wheeled tractors) 5.7.1 The center of the test site is shown on the ground. The center of the test area is marked on the ground. The measurement area starts at A4 and ends at B. The device is placed at P and P.
5.1.2 A sound level meter is fixed with a tripod at PP and P respectively. Its diaphragm is placed at P, F and F. The microphone is placed 1.2m above the ground to the line of sight. The microphone is perpendicular to CC and is aligned with the ground. The sound level is measured in reverse with the "A" weighted and fast gear. .13 Before the test starts, first measure the prohibited test points. The high-altitude overtaking is accurate, and the speed is recorded as the speed of three-quarters of the time.
5.1.4 During the test, the tractor is in the lowest gear and driving along the center line of the runway. It approaches the AA line at a speed of three-quarters of the speed. When the front of the tractor reaches the AA line, the throttle is increased to the maximum and the rear end of the tractor leaves the B line. As soon as possible, the throttle is lowered to the lowest speed position and the highest reading of the sound meter is recorded when the tractor passes the measuring area. The sound transmission difference
The test is repeated twice in a row. The difference between the two consecutive measurement results should not be greater than 2dB (A), including the difference between the two consecutive measurement results.
5.1.5 For a two-wheeled tractor, if the instruction manual stipulates that the front wheel drive should be opened during transportation operations, the test should be carried out with both wheels in the state of two-wheeled driving. 5.2 Noise measurement at the driver's operating position 52.1 Place the microphone on a dedicated frame (with vibration reduction measures) in the driver's operating position. The microphone's diaphragm is 200 + 20 mm above (or 700 ± 50 mm above) and 10 mm in front of the driver's operating position. The microphone is fixed horizontally on the side of the driver's operating position: the "A" weight and compensation of the meter are measured. 36 GB/T 3871. 8-93 5.2. When testing a tractor equipped with a cab, all doors should be closed. If the tractor can operate with the doors tightly open, the test should be carried out in both closed and open states. During the test, various equipment in the cab are in normal operation. The tractor travels along the track in reverse, maintaining a theoretical speed of 4~10km/h for the tractor and 4~16km/h for the wheeled tractor. In each gear, the engine throttle is fully opened and the traction load is increased until the engine speed drops to the rated speed of 15 for the wheeled tractor. In slow mode, the noise level is maximum. After the noise level is reduced by 5%, the corresponding noise caused by the traction and towing machine is read. For stepless tractors, the noise caused by the four speed changes should be evenly distributed within the speed range specified above, and the peak noise caused by the traction and towing machine during the test shall not be recorded.
Finally, the maximum noise level of the tractor when it is running empty shall be measured at the gear closest to the theoretical speed, /h (wheel type) or / (track type).
5.2.3 For four-wheeled tractors, if the front drive can be disengaged, the noise level shall be measured in accordance with Article 5.2.2 under the two-wheel drive and four-wheel drive conditions.
5.3 At the end of each test, measure the background noise level. 6 Test Results and Report
6.1 Record the test conditions of each test in the summary table. For the measurement results in Article 5.1, enter the maximum value in the table. For the measurement results in Article 5.2, enter the theoretical maximum value of 7.5m/h [wheel type>6km/h (track type)] and the value shall be 1dB higher than that of the gear.
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