Agricultural tractors. Test procedures - Low temperature starting
1Key Takeaways
1 Scope This part of ISO 789 specifies the test procedure for determining the lowest temperature at which the tractor starter motor is able to start the tractor engine.
2Expert Interpretation
Professional interpretation of BS ISO 789-12:2000 agricultural tractor cold start test standard, covering test conditions, fuel specifications, lubrication system requirements and cold start judgment criteria, suitable for agricultural machinery research and development and quality inspection fields.
Standard Overview and Scope of Application
BS ISO 789-12:2000 specifies the test method for the engine starting performance of agricultural tractors in low temperature environments, and evaluates the reliability of the starting system under extreme temperature conditions through scientific quantitative indicators. This standard is applicable to wheeled and crawler tractors with a rated power of ≤100kW.
Core Test Parameters
| Test Items | Technical Indicators | Allowable Deviation |
|---|---|---|
| Ambient Temperature | -15℃ Reference Value | ±2℃/h Fluctuation |
| Fuel Temperature | Measurement in the middle of the tank | ±2℃ |
| Start Judgment | Autonomous Operation within 30 Seconds | 5 Trials |
Key Test Conditions
4.1 Fuel System Requirements
Before the test, the original fuel system must be completely drained and replaced with low-temperature fuel that meets the ISO 3675 density standard and ISO 5163/5164 octane number requirements, and the pour point (ISO 3016) must be recorded. Diesel engines must also measure the cetane number (ISO 5165).
4.2 Lubrication system specifications
The engine and transmission must use low-temperature lubricants recommended by the manufacturer, and the oil level must be confirmed again after warm-up. Typical low-temperature engine oil viscosity grades include 5W-30 or 0W-40.
Key points for test implementation
5.1 Temperature stability control
The tractor must be left stationary in the test environment for more than 24 hours to ensure that the temperature change of fuel, oil and coolant is ≤2℃/h. The ambient temperature measurement points must be arranged at 4 positions at the center height of the engine crankshaft.
5.2 Criteria for Starting
A successful start is defined as: within 30 seconds after the starter is activated, the engine can run autonomously under the control of the governor. Auxiliary devices such as preheating plugs and battery insulation sleeves certified by the manufacturer are allowed.
Technology Evolution Analysis
The 2000 edition of this standard for the first time made low-temperature starting performance a separate chapter. Compared with the early comprehensive test standards, its innovations include:
- Introduction of temperature gradient test method (±2.5℃ step)
- Clear battery pretreatment requirements
- Standardize multi-position temperature monitoring scheme
Implementation suggestions
- Complete fuel system replacement 72 hours before testing
- The backup battery needs to be treated with low temperature synchronously with the equipment under test
- It is recommended to cooperate with ISO 789-4 for emission performance correlation testing