GB/T 18861-2012 PDF English
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Test methods of rolling resistance for motor vehicle tyres and motorcycle tyres -- Multi-point test
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GB/T 18861-2012: PDF in English (GBT 18861-2012) GB/T 18861-2012
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.160.10
G 41
Replacing GB/T 18861-2002
Test methods of rolling resistance for motor vehicle tyres and
motorcycles tyres - Multi-point test
(ISO 18164:2005, Passenger car, truck, bus and motorcycle tyres - Methods of
measuring rolling resistance, MOD)
ISSUED ON: DECEMBER 31, 2012
IMPLEMENTED ON: SEPTEMBER 01, 2013
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
National Standardization Administration.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Measurement methods ... 7
5 Test equipment ... 7
6 Test conditions ... 9
7 Test procedures ... 10
8 Data processing ... 14
9 Data analysis ... 17
Appendix A (Informative) Comparison of chapter numbers between this standard and
ISO 18164:2005 ... 19
Appendix B (Informative) Technical differences between this standard and ISO
18164:2005 and their reasons ... 20
Appendix C (Normative) Accuracy of test equipment ... 21
Appendix D (Informative) Optional test conditions ... 24
Appendix E (Informative) Method for determining the moment of inertia of the drum
and the moment of inertia of the tyre and rim assembly - Deceleration method ... 26
Test methods of rolling resistance for motor vehicle tyres and
motorcycles tyres - Multi-point test
1 Scope
This standard specifies a method, for measuring the rolling resistance of new car, truck
and motorcycle tyres, under controlled laboratory conditions.
This standard applies to new car pneumatic tyres, truck pneumatic tyres, motorcycle
pneumatic tyres, except for tyres only for temporary replacement use.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 2977 Size designation, dimensions, inflation pressure and load capacity for
truck tyres
GB/T 2978 Size designation, dimensions, inflation pressure and load capacity for
passenger car tyres
GB/T 2983 Series of motorcycle tyres (GB/T 2983-2008, ISO 4249-1:1985,
Motorcycle tyres and rims (code-designated series) – Part 1: Tyre; ISO 4249-2:1990,
Motorcycle tyres and rims (code-designated series) -Part 2: Tyre load ratings; ISO
4249-3:2004, Motorcycle tyres and rims (code-designated series) - Part 3: Rims;
ISO 5751-1:2004, Motorcycle tyres and rims (metric series) - Part 1: Design guides;
ISO 5751-2:2004, Motorcycle tyres and rims (metric series) - Part 2: Tyre
dimensions and load-carrying capacities; ISO 5751-3:2004, Motorcycle tyres and
rims (metric series) - Part 3: Range of approved rim contours; ISO 5995-1:1982,
Moped tyres and rims - Part 1: Tyres; ISO 6054-1:1994, Motorcycle tyres and rims
(code-designated series) - Diameter codes 4 to 12 - Part 1: Tyres, NEQ)
GB/T 6326 Tyre terms and definitions (GB/T 6326-2005, ISO 4223-1:2002,
Definitions of some terms used in tyre industry - Part 1: pneumatic tyres, NEQ)
5.1.1 Drum diameter
The diameter of the drum of the testing machine is as follows: The diameter of the drum
for car and motorcycle tyres is at least 1.5 m (the standard drum diameter is 1.7 m); the
diameter of the drum for truck tyres is at least 1.7 m. The values of rolling resistance
and rolling resistance coefficient shall be expressed as values for a 1.7 m drum. It shall
be noted that the rolling resistance results are different for different drum diameters.
According to 9.3, if necessary, different drum diameters can be converted.
5.1.2 Drum surface quality
The outer surface of the drum shall be smooth steel or textured; it shall be kept clean.
The roughness of the steel surface shall comply with the requirements given in C.6. See
Appendix D.4 for textured drumheads.
5.1.3 Drumhead width
The drum surface width shall be greater than the running surface width of the test tyre.
5.2 Test rims
The tyre shall be mounted on the test rim, which is specified in Appendix C.
5.3 Load, positioning, control, instrument accuracy
The tyres, their loads and positioning shall comply with the requirements given in C.3.
The control accuracy shall comply with the provisions of C.4. The instrument accuracy
shall comply with the provisions of C.5.
5.4 Ambient temperature
5.4.1 Standard ambient temperature
The standard ambient temperature is 25 °C. The ambient temperature shall be measured
on the extension line of the wheel axle centerline, at 0.15 m ~ 1 m away from the nearest
sidewall surface of the tyre.
5.4.2 Allowable ambient temperature
If the standard ambient temperature cannot be reached, the test is allowed within the
ambient temperature range of 20 °C ~ 30 °C. However, the test data shall be corrected
to the rolling resistance value under standard ambient temperature conditions,
according to 9.2.
5.4.3 Drum surface temperature
At the beginning of the test, the temperature of the outer peripheral surface of the drum
is approximately the same as the ambient temperature.
pressure of passenger car tyres, truck tyres, motorcycle tyres shall comply with the
provisions of Table 2. The control accuracy of the test starting air pressure shall comply
with the provisions of C.4.1.
6.5 Time and velocity variables of deceleration method
When the deceleration method is selected, the increment of running time (Δt) shall not
be greater than 0.5 s; the variation of test speed shall not be greater than 1 km/h.
6.6 Selected test conditions
If it is necessary to conduct a sensitivity test of tyre pressure, load, speed to tyre rolling
resistance, please refer to the test conditions given in Appendix D.
7 Test procedures
7.1 General
The stages of the test procedure shall be carried out in the order given below.
7.2 Test run
Install the test tyre on the measuring rim. Inflate it according to the test air pressure,
which is specified in 6.4. Install it on the testing machine. Run it for at least 1 hour,
according to the test load specified in 6.3 and at a test speed not lower than that specified
in 6.2.
7.3 Thermal balance
Place the tyre and rim assembly at the test site. Place the test tyre at the test ambient
temperature, to reach thermal equilibrium, to allow the test tyre to reach the ambient
temperature. The thermal equilibrium time of car and motorcycle tyres is more than 3
hours; the thermal equilibrium time of truck tyres is more than 6 hours.
7.4 Air pressure adjustment
After thermal equilibrium, check the air pressure of the test tyre; adjust it to meet the
requirements of 6.4; recheck after 10 minutes, to ensure the specified test air pressure
of the tyre.
7.5 Warm up
Warm up the test tyre and drive it, according to the test load specified in 6.3 and the test
speed specified in 6.2, until its rolling resistance value becomes stable. The minimum
warm-up driving time shall comply with the requirements in Table 3.
- Car tyres and motorcycle tyres: Recommended value is 100 N, but no more than
200 N;
- Truck tyres (load index ≤ 121): Recommended value is 150 N. However, for
equipment specially designed for car tyres or light truck tyres, it shall not
exceed 200 N; OR for equipment specially designed for truck tyres, it shall not
exceed 500 N;
- Truck tyres (load index > 121): Recommended value 400 N, but not exceeding
500 N;
- For standard tests and calibration tests, the skim test load values shall be the
same;
b) Record the applicable data, in axle force (Ft), input torque (Tt) or input power;
c) Record the tyre load (Lm) perpendicular to the drum surface.
Note 1: In addition to the force measurement method, the measured values include bearing
losses and aerodynamic losses of the tyre rim assembly and drum.
Note 2: The bearing friction -- between the tyre shaft and the drum -- depends on the applied
load. Therefore, the value of the bearing friction when measuring the axle force under load is
different from when measuring the parasitic loss using the skim test reading. In practice,
however, the difference is negligible.
7.7.3 Machine method
The machine method is carried out, according to the following procedure:
a) Move the tyre away from the drum;
b) Record the input torque and input power at the test speed.
Note: Measurements include bearing and aerodynamic losses of the tyre rim assembly and drum.
7.7.4 Deceleration method
The deceleration method is carried out, according to the following procedure:
a) Move the tyre away from the drum surface;
b) Record the deceleration of the drum and the deceleration of the unloaded
tyre .
Note 1: Measurements include bearing and aerodynamic losses of the tyre rim assembly and
drum, which also need to be considered.
Note 2: It is well known that the bearing friction of the tyre shaft and the drum depends on the
applied load; therefore, the value of the bearing friction, when measuring the deceleration under
load, is different from that when measured by the skim test method. In practice, however, the
difference is negligible.
8 Data processing
8.1 Calculation of parasitic losses
8.1.1 General
The parasitic loss Fpl at the tyre/drum interface shall be calculated, based on the force
Ft, torque, power or deceleration, according to the formulas 8.1.2 ~ 8.1.5 below,
expressed in N.
8.1.2 Force measurement method
The parasitic loss Fpl, represented by N, is calculated according to formula (1):
Where:
Ft - Axle force (see 7.7.2), in Newton (N);
rL - The distance from the center line of the tyre shaft to the outer surface of the
drum, under steady state, in meters (m);
R - Radius of drum, in meters (m).
8.1.3 Torque method
The parasitic loss Fpl, represented by N, is calculated according to formula (2):
Where:
Tt - Input torque (see 7.7.2), in Newton meter (N·m);
R - Radius of drum, in meters (m).
8.1.4 Power method
The parasitic loss Fpl, represented by N, is calculated according to formula (3):
Where:
Ft - Axle force, in Newton (N);
Fpl - Parasitic loss calculated according to Article 8.1.2, in Newton (N);
rL - Under steady-state conditions, the distance from the center line of the tyre shaft
to the outer surface of the drum, in meters (m);
R - Radius of drum, in meter (m).
8.2.3 Drum shaft torque method
The rolling resistance Fr is calculated by formula (6), unit in N:
Where:
Tt - Input torque, in Newton meter (N·m);
Fpl - Parasitic loss calculated according to 8.1.3, in Newton (N);
R - Radius of drum, in meter (m).
8.2.4 Power method
The rolling resistance Fr is calculated by formula (7), unit in N:
Where:
V - The voltage of the driving motor of the testing machine, in volts (V);
A - The current of the driving motor of the testing machine, in amperes (A);
Un - The drum speed, in kilometers per hour (km/h);
Fpl - The parasitic loss calculated according to 8.1.4, in Newton (N).
8.2.5 Deceleration method
The rolling resistance Fr is calculated by formula (8), unit in N:
Where:
ID - Moment of inertia of the drum (see Appendix E), in kilogram square meter
(kg·m2);
R - Radius of drum, in meters (m);
Fpl - Parasitic loss calculated according to 8.1.5, in Newton (N);
Δtv - Time increment selected during measurement, in seconds (s);
Δwv - Angular velocity increment of the test drum when the tyre is loaded, in radians
per second (rad/s);
IT - Moment of inertia of the wheel shaft and tyre rim assembly, in kilogram square
meter (kg·m2);
Rr - Tyre rolling radius, in meters (m);
Fr - Rolling resistance, in Newton (N).
Note: See Appendix E for guidance and examples of measuring moment of inertia for
deceleration method.
9 Data analysis
9.1 Rolling resistance coefficient
The rolling resistance coefficient Cr is calculated by dividing the rolling resistance by
the tyre test load, using the formula (9):
Where:
Fr - Rolling resistance, in Newton (N);
Lm - Test load, in kilonewton (kN).
9.2 Temperature correction
The test temperature range is 20 °C ~ 30 °C. If the measurement is performed at a
temperature other than 25 °C, use the formula (10) for temperature correction, where
Fr25 is the rolling resistance at 25 °C, represented by N:
Appendix C
(Normative)
Accuracy of test equipment
C.1 Overview
In order to ensure the repeatability of the test results and to have good correlation
between the tyre test results, which are obtained on each test equipment, it is necessary
to stipulate the accuracy of the test equipment. The provisions in this Appendix are
necessary conditions for obtaining reliable test results; however, they are not all design
requirements for test equipment.
C.2 Test rim
C.2.1 Width
The width of the test rim shall conform to the measured rim width for the test tyre
specification, which is specified in the corresponding standard. The width of the car
tyre test rim shall comply with the requirements of GB/T 2978; the width of the truck
tyre test rim shall comply with the requirements of GB/T 2977; the width of the
motorcycle tyre test rim shall comply with the requirements of GB/T 2983.
C.2.2 Deviation
The deviation of the test rim shall meet the following requirements:
a) The maximum radial runout at the tyre seat is not greater than 0.5 mm;
b) The maximum axial runout at the rim is not greater than 0.5 mm.
C.3 Positioning
C.3.1 Loading direction
The loading direction of the test tyre shall be perpendicular to the contact center plane,
between the tyre and the drum. Meanwhile, it shall pass through the center of the wheel.
The allowable deviation is as follows:
a) In the force measurement method and deceleration method, it is not more than
0.06° (1 mrad);
b) In the torque method and power method, it is not more than 0.29° (5 mrad).
C.3.2 Tyre alignment
C.3.2.1 Wheel camber angle
The center plane of the wheel shall be perpendicular to the center plane of contact,
between the tyre and the drum. In any measurement method, the wheel camber angle
shall not be greater than 0.11° (2 mrad).
C.3.2.2 Tyre slip angle
The forward direction of the center of contact -- between the test tyre and the drum --
shall be parallel to the center plane of the wheel. In any measurement method, the slip
angle of the test tyre shall not be greater than 0.06° (1 mrad).
C.4 Control accuracy
C.4.1 Overall accuracy
In addition to disturbances due to non-uniformity of the test tyre and rim, the test
equipment shall be able to measure the changing values of each variable, within the
following range:
a) Tyre test pressure: ±3 kPa;
b) Test load: ±20 N for load index 121 and below; ±45 N for load index 122 and
above;
c) Test speed (drum outer peripheral surface speed): ±0.5 km/h in the force
measurement method; ±0.2 km/h in the torque method, power method,
deceleration method;
d) Time: ±0.02 s;
e) Angular velocity: ±0.2% of measured value.
C.4.2 Compensation for interference between load and axle force and load
direction deviation
When using the force measurement method, one of the following methods shall be used,
to eliminate the interference between the load and the axle force, as well as the influence
of the load direction deviation on the axle force.
a) By measuring the axle force of the test tyre in forward and reverse rotation,
subtract the "reverse rotation" value from the "forward rotation" value, then
divide the calculation result by 2, as the compensated axle force value;
b) Through the calibration of the test equipment, find the compensation coefficient
correction measurement value of the load and axle force.
C.5 Instrument accuracy
Instruments used to measure and record test data shall have the accuracy, which is
formula (E.1) (the friction moment of the pulley bearing is ignored):
Where:
ID - Moment of inertia of the drum, in kilogram square meter (kg·m2);
m - The mass of the weight, in kilograms (kg);
g - Acceleration due to gravity, which takes 9.81 m/s2;
R - Radius of drum, in meter (m);
C - Friction torque of drum bearing, in Newton meter (N·m);
ΔwD/Δt - Angular acceleration or angular deceleration of the drum, in radians per
square second (rad/s2);
Ip - Moment of inertia of the pulley, in kilogram square meter (kg·m2);
r - Pulley radius, in meters (m).
E.2.1.3 Method
When a weight, which has a known mass, is hung on one end of the wire rope, the drum
rotates under the gravity of the weight. The angular acceleration of the drum can be
measured through an angle encoder and a timer, which are installed on the drum shaft.
After the weight has gained sufficient momentum, separate the wire rope from the drum;
then measure the angular deceleration of the drum. Its relationship with the friction
moment of the drum bearing can be expressed by formula (E.2), as follows:
Where:
C - Friction torque of drum bearing, in Newton meter (N·m);
ID - Moment of inertia of the drum, in kilogram square meter (kg·m2);
ΔwD/Δt - Angular deceleration of the drum, in radians per square second (rad/s2).
E.2.2 Estimation method
First calculate the moment of inertia of each component of the drum. Then find their
sum, using the formula (E.3):
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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