JT/T 711-2016Limits and measurement methods of fuel consumption for commercial vehicle for passenger transportation (English PDF)

5.2.2 The meteorological conditions and preparation of test vehicle during the

test shall comply with the provisions of GB/T 12534.

5.2.3 Vehicle's tire pressure, fuel, lubricant (grease), brake fluid, brake air-

pressure, engine coolant, etc. shall comply with the provisions of GB/T 12534 and vehicle manufacturers.

5.2.4 Test vehicle's tires are selected in order according to the following principles:

a) When the vehicle may be equipped with bias tires and radial tires, it shall select the bias tires;

b) When the vehicle may be equipped with tires of different outer diameters, it shall select the tires of small outer diameters;

c) When the vehicle may be equipped with tires of different cross-sectional widths under the same outer diameter of the tire, it shall select the tires with a large cross-sectional width.

5.2.5 The main test instruments and the requirements for the maximum

allowable error/accuracy grades are as follows:

a) Measuring instrument of vehicle's speed: the maximum allowable error is

±0.5%;

b) Fuel flow meter: the maximum allowable error is ±0.5%;

c) Timer: the minimum division value is 0.1 s;

d) Engine tachometer: the maximum allowable error is ±1%;

e) Weighing instrument: the accuracy grade is grade-3 and above.

5.2.6 During the test, it shall close the vehicle's windows, cab's vent and air- conditioners. It only allows for the equipment necessary to drive the vehicle to run.

5.3 Test methods

5.3.1 Constant-speed driving conditions

5.3.1.1 The vehicle is fully-loaded. The vehicle of manual transmission shall be in the highest gear or the second-highest gear. When the highest gear cannot meet the requirements for test speed, use the second-highest gear. The vehicle of the automatic transmission shall be in the gear-D. At each test speed, let the vehicle drive stably for at least 100 m to pass a 500 m test road at constant- speed, to measure the time and fuel consumption of the vehicle when passing measurement results.

5.3.2.3 The difference between the starting speed & final speed and the

specified speed during the test shall be within the range of -2 km/h ~ 0 km/h and 0 km/h ~ 2 km/h, respectively.

5.3.2.4 For the acceleration test, it shall make two measurements (round-trip) along the test road.

5.3.2.5 The test results shall be subjected to repeatability verification in accordance with the provisions of GB/T 12545.2.

5.3.3 Idle condition

5.3.3.1 The measurement of the fuel consumption at idle conditions shall be carried out immediately after the end of the test at constant-speed condition and the accelerated condition.

5.3.3.2 When measuring, the vehicle shall be stationary, the clutch is in the engaged position, the manual transmission is in the neutral position, the vehicle of automatic transmission shall be in the “parking” or “P” position. The accelerator pedal is in the fully-released position, the engine's speed shall be kept at the idle speed as specified by the vehicle manufacturer, with a speed variation of ±50 r/min.

5.3.3.3 The measurement of fuel consumption at idle speed shall be started

300 s after idling, made for 3 times, 300 s per measurement. Record the fuel consumption at idle speed and the engine speed, take the average of the 3 measurement results.

5.4 Correction of fuel consumption

5.4.1 Correction of fuel consumption in constant-speed conditions

Take the arithmetic mean value of the measurement results of fuel consumption which are made at the same test speed according to the test method of 5.3.1 as the measured value of the constant-speed fuel consumption of the vehicle at this speed, make correction of standard status according to the method as specified in GB/T 12545.2.

5.4.2 Correction of fuel consumption in accelerated conditions

Take the arithmetic mean value of the measurement results of fuel consumption under accelerated conditions which are made according to the test method of

5.3.2 as the measured value of the accelerated-speed fuel consumption, make correction of standard status according to the method as specified in GB/T

12545.2.