Coastdown test method of motor vehicles
1Key Takeaways
This standard specifies the test conditions and test methods for road coasting tests on various types of vehicles. This standard is applicable to various types of vehicles.
2Expert Interpretation
In-depth analysis of GB/T 12536-2017 "Motor Vehicle Coasting Test Method", covering the test background, technical requirements, implementation steps and comparative analysis, to help you fully understand the industry standard.
Interpretation of GB/T 12536-2017 National Standard of the People's Republic of China
Foreword and revision background
GB/T 12536-2017 "Automobile Coasting Test Method" was drafted according to the rules given in GB/T1.1-2009, and replaced the old standard GB/T12536-1990. The main technical changes of the new standard include adding term definitions, refining test conditions and methods, and especially adding test requirements for automatic transmission vehicles.
Test conditions and environmental requirements
The test road surface must be a hard, straight, clean, dry and sufficiently long asphalt or concrete road surface. The longitudinal slope shall not exceed 0.1%, and the transverse slope shall not exceed 3%. At the same time, the wind speed during the test shall not exceed 3.0m/s, the relative humidity shall be less than 95%, and the atmospheric temperature shall be between 0℃ and 40℃.
Vehicle Conditions and Preparations
| Vehicle Category | Test Mass Requirements | Load Distribution Requirements |
|---|---|---|
| M1-category vehicles and N1-category vehicles with a maximum design gross mass of less than 2t | When 50% of the maximum permissible load mass does not exceed 180kg, the test mass is the vehicle curb mass plus 180kg; when it exceeds 180kg, the test mass is the vehicle curb mass plus 50% of the maximum permissible load mass. | Load distribution should be as uniform as possible. |
| M2, M3-category vehicles and N-category vehicles with a maximum design gross mass of not less than 2t | Full load conditions apply, M2, M3-category city buses are 65% of the load mass; other vehicles are fully loaded. | Uniformly distribute according to the requirements of GB/T12428 and GB/T12534. |
Test method and data recording
The test vehicle should stop accelerating before entering the coasting section and maintain a stable driving state. The manual transmission gear position is in neutral and the clutch pedal is released, and the automatic transmission gear position is in N gear. During the test, the vehicle needs to drive in a straight line, and the coasting distance and initial speed from 50km/h coasting to complete stop are recorded.
Comparison with the old standard
| Comparison dimensions | New standard GB/T12536—2017 | Old standard GB/T12536—1990 |
|---|---|---|
| Terms and definitions | Added detailed term definitions. | Term definitions were not clarified. |
| Test conditions | Detailed requirements for roads, environment, measurement parameters, etc. | Only basic test conditions were mentioned. |
| Test methods | Added test requirements for automatic transmission vehicles, and clarified the way to record the coasting distance and speed. | The test steps were not described in detail. |
Implementation recommendations
To ensure the accuracy of test data:
- Strictly comply with vehicle preparation and test conditions, especially wind speed, humidity and temperature control.
- Use high-precision measuring instruments and record parameters in accordance with standard requirements.
- For automatic transmission vehicles, ensure that the energy recovery device does not interfere with the coasting test in N gear.