1 Subject Content and Application Scope
This standard specifies the test method of motor vehicles' coastdown.
This standard is applicable to all kinds of motor vehicles.
2 Normative References
GB/T 12534 Motor Vehicles-General Rules of Road Test Method
3 Testing Conditions
3.1 Measuring apparatus
The fifth wheel gauge or the corresponding recording device of speed and travel distance, with an accuracy of not less than 0.5%.
3.2 The door and window of the motor vehicle shall keep closing.
3.3 Other test conditions and test vehicles are prepared according to the requirements of GB/T 12534.
4 Test Methods
4.1 The surveyor's poles shall be erected at both ends of the test road section about 1 000 m long, acting as the coastdown section. The motor vehicle shall keep a speed slightly exceeding 50 km /h before it enters into the coastdown section.
4.2 Before the motor vehicle enters into the coastdown section, the driver shall change the gearshift into free position (disconnecting the clutch pedal), and then start the coastdown. As the speed reaches 50 km /h (the motor vehicle shall enter into the coastdown section), the record shall be kept on with the help of the fifth wheel gauge until the motor vehicle stops completely. The driver shall not rotate the steering wheel in the process of coastdown.
4.3 The initial speed (shall be 50±0.3 km /h) and the coastdown distance shall be recorded.
4.4 The coastdown testing shall be carried out at least once both fro. And to; and the section of both direction shall be superposed as much as possible .The result shall be recorded in Table 1.
