GB/T 45146-2024 PDF English
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GB/T 45146-2024: Road vehicles - Air and air/hydraulic braking systems of motor vehicles test procedures
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GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.040.40
CCS T 24
Road Vehicles - Air and Air / hydraulic Braking Systems
Motor Vehicles Test Procedures
(ISO 7635.2006, Road Vehicles - Air and Air / hydraulic Braking Systems of
Motor Vehicles, Including Those with Electronic Control Functions - Test
Procedures, MOD)
Issued on: DECEMBER 31, 2024
Implemented on: JULY 1, 2025
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative References... 5
3 Terms and Definitions... 5
4 Symbols... 6
5 Test Site and Environmental Conditions... 7
6 General Requirements... 8
7 Test Sequence... 10
8 Test Preparation... 12
9 Static Test and Inspection... 15
10 Basic Performance Test - No-load... 21
11 Failure Test - No-load... 23
12 ABS Test - No-load... 26
13 ABS Test - Full-load... 26
14 Failure Test - Full Load... 26
15 Basic Performance Test - Full Load... 26
Appendix A (informative) Table of Comparison of Structure No... 36
Appendix B (informative) Table of Technical Differences and Causes for the
Differences... 38
Bibliography... 41
Road Vehicles - Air and Air / Hydraulic Braking Systems of
Motor Vehicles Test Procedures
1 Scope
This document specifies the general requirements and describes the test methods for air and air
/ hydraulic braking systems for road vehicles.
This document applies to Category M2, M3, N2 and N3 vehicles equipped with the air and air /
hydraulic braking systems as defined in GB/T 5620 and satisfying the provisions of GB/T
15089.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 5620 Road Vehicles - Vocabulary and Definition for Braking of Automotive Vehicles and
Their Trailers (GB/T 5620-2020, ISO 611.2003, IDT)
GB 12676-2014 Technical Requirements and Testing Methods for Commercial Vehicle and
Trailer Braking Systems
GB/T 13594 Antilock Braking Performance and Testing Procedure for Motor Vehicles and
Their Trailers
GB 34660 Road Vehicles - Requirements and Test Methods of Electromagnetic Compatibility
ISO 11992 (all parts) Road Vehicles - Interchange of Digital Information on Electrical
Connections between Towing and Towed Vehicles
ISO 21069-1 Road Vehicles - Test of Braking Systems on Vehicles with a Maximum Authorized
Total Mass of over 3.5 t Using a Roller Brake Tester - Part 1.Pneumatic Braking Systems
ISO 21069-2 Road Vehicles - Test of Braking Systems on Vehicles with a Maximum Authorized
Total Mass of over 3.5 t Using a Roller Brake Tester - Part 2.Air over Hydraulic and Purely
Hydraulic Braking Systems
3 Terms and Definitions
The terms and definitions defined in GB/T 5620, GB 12676-2014 and GB/T 13594, and the
following are applicable to this document.
3.1 pressure indicated by manufacturer
The pressure in the energy storage device specified by the manufacturer.
NOTE. this is generally the cut-in pressure specified in GB/T 5620.
3.2 maximum pressure
The pressure available for normal vehicle operation.
a) If a pressure regulating device is installed, then, it is the cut-out pressure of the device;
b) For air compressors equipped with a pressure limiting function, then, it is 90% of the
ultimate pressure.
3.3 minimum pressure
The pressure available for normal vehicle operation.
a) If a pressure regulating device is installed, then, it is the re-energizing pressure of the
device;
b) For air compressors equipped with a pressure limiting function, then, it is 90% of the
limiting pressure indicated by the manufacturer.
4 Symbols
The following symbols apply to this document.
am. average braking deceleration.
E. wheelbase.
F. actuation force.
Fi. normal reaction force of the road surface on the ith axis under static conditions (the value of
i is 1, 2, 3, etc.).
FMd. total normal static reaction force of the road surface on the unbraked and driven axles of a
motor vehicle.
FMnd. total normal static reaction force of the road surface on the unbraked and non-driven axles
of a motor vehicle.
FWm. rolling resistance, 0.01 FMnd + 0.015 FMd.
g. acceleration of gravity.
h. height of center of mass.
kHpeak. maximum value on the “adhesion coefficient vs. slip ratio” curve on a high-adhesion
road surface.
kLpeak. maximum value on the “adhesion coefficient vs. slip ratio” curve on a low-adhesion road
surface.
n. number of braking operations.
PM. vehicle mass.
p1.65% of p2.
p2.pressure specified by the manufacturer to achieve the specified performance of the service
brake system.
t0.average test time.
t1, t2, t3.pumping time.
v. vehicle speed.
vmax. maximum vehicle speed.
v1.speed at the start of braking.
v2.speed at the end of braking.
t. duration of the braking cycle (the time elapsed between the start of one braking operation
and the start of the next).
5 Test Site and Environmental Conditions
5.1 Test Site
The test site should be sufficiently open and free of obstacles to ensure safety.
The test site shall have an acceleration path of sufficient length before the test area to allow
vehicles to reach the test vehicle speed.
The test site should have.
a) Sufficient length to ensure that vehicles with poor braking performance can complete
the test;
b) Sufficient width to ensure the safety of vehicles with poor directional stability during
braking.
5.2 Road Surface Conditions
5.2.1 Road surface
The test area shall be dry, flat and hard. Unless otherwise specified, the coefficient of adhesion
shall not be less than 0.8.
5.2.2 Slope
5.2.2.1 The slope over any 50 m longitudinal length of the test road shall be less than 1%.
5.2.2.2 Type II and Type IIA road surface conditions are shown in Table 1.
5.2.2.3 The parking brake system hill-hold test may be conducted on the slope specified in 10.3
and 15.1 or on a level surface.
5.2.3 Camber
The camber or transverse slope of the road surface shall not exceed 2%.
5.3 Environmental Conditions
5.3.1 Wind speed
During the test, the wind speed shall not exceed 5 m/s.
5.3.2 Ambient temperature
The ambient temperature shall not exceed 35 °C.
6 General Requirements
6.1 Braking performance tests shall adhere to the following general conditions.
a) Conduct the test at the specified vehicle speed;
b) DO NOT exceed the maximum allowable operating force;
c) Test with the engine engaged or disengaged as specified;
d) Unless otherwise specified, test results are valid only if no wheel lock occurs at a
speed greater than 15 km/h;
e) Test results are valid only if the steering wheel angle does not exceed 90° on one side
during braking;
f) Unless otherwise specified, all tests should be conducted with the vehicle fully loaded
or unloaded.
6.2 During the test, braking performance and any abnormal vehicle driving conditions, such as
deviation or abnormal vibration, shall be observed and recorded.
6.3 For vehicles equipped with a manual transmission, during the engine engagement test, the
clutch may be disengaged before the vehicle comes to a stop to avoid engine stalling.
6.4 Unless otherwise specified, the deceleration used in the test shall be the “fully developed
average deceleration” as defined in GB 12676-2014.
6.5 On the premise of ensuring safety, tests may be conducted under adverse environmental
conditions; however, such adverse conditions shall be indicated in the report. If a test fails under
adverse conditions, the test shall be repeated under specified conditions.
6.6 The test sequence should comply with the provisions of Chapter 7.
6.7 After a test failure or replacement of a braking system component, all or part of the test
shall be repeated in accordance with the test sequence. Before re-testing, appropriate actuation
checks shall be performed to confirm that the braking system is properly functioning. After
replacing the brake drum / disc and brake linings, a run-in shall be performed in accordance
with 8.2.2.
6.8 During the test, the required operating force shall be promptly applied and without
significant overshoot. Unless otherwise specified, the operating force shall remain stable
throughout the braking process. Adjustable devices should be used to control the operating force
or stroke for testing.
6.9 Except for the thermal-state braking performance test, all tests shall start in a cold state,
with the temperature measured on the brake drum / disc friction surface below 100 °C.
6.10 Unless otherwise specified, before the test starts, the initial test vehicle speed shall be
stabilized at no less than 98% of the specified test vehicle speed.
6.11 When the vehicle’s maximum speed is lower than the specified test vehicle speed, the test
shall be conducted at the vehicle’s maximum design vehicle speed.
6.12 The braking performance test with the engine engaged shall be conducted in an appropriate
gear, typically the highest gear used for the specified test vehicle speed, with the engine speed
8.2 Braking System Condition and Running-in
8.2.1 The braking system components shall be in a newly manufactured condition or have
equivalent properties and be within the vehicle manufacturer’s approved scope.
8.2.2 The brakes should be run-in in accordance with the manufacturer’s specified running-in
procedures or under the following conditions.
a) For vehicles with front / rear disc brakes.
1) Initial vehicle speed is 60 km/h, brake to 20 km/h;
2) First, brake 30 times at a braking deceleration of 2 m/s2, then, brake 30 times at
a braking deceleration of 4 m/s2.
b) For vehicles with front disc / rear drum brakes or front / rear drum brakes.
1) Initial vehicle speed is 60 km/h, brake to 20 km/h;
2) First, brake 100 times at a braking deceleration of 2 m/s2, then, brake 100 times
at a braking deceleration of 4 m/s2.
c) During the run-in process, the temperature of the brake disc and / or brake drum shall
not exceed 200 °C.
d) The contact area between the brake lining after running-in and the brake drum or
brake disc shall not be less than 80% of the total area, and the brake lining surface
shall not manifest phenomena of polishing, ablation or damage.
8.3 Brake Adjustment
The brake clearance adjustment device, including the automatic clearance adjustment device in
the brake, shall be adjusted in accordance with the vehicle manufacturer’s specifications. Before
each test, the brake may be re-adjusted. Before Type I test, perform the test in accordance with
the provisions of 15.9.3.
8.4 Tire Condition
8.4.1 Tires shall be inflated to the pressure recommended by the vehicle manufacturer.
8.4.2 Tire tread wear should not exceed 50% of total wear, and brand-new tires should not be
used.
8.5 Test Devices and Instruments
8.5.1 General
Care should be taken to ensure that the devices and instruments installed in the vehicle’s braking
system do not significantly affect the performance of the braking system.
9.1.1 Static braking force test
In accordance with ISO 21069-1 and ISO 21069-2, use a roller brake test bench to test the
maximum braking force under static conditions.
9.1.2 Operating force and control pipeline pressure test
Actuate the service, emergency, and parking brake operating devices to increase the operating
force from 0 N to the maximum. At the brake chamber or at the air / hydraulic conversion point,
measure the static pressure curve. If the pressure values are composed of a series of
independently measured data, then, at least five sets of readings should be taken, including the
initial braking pressure. If necessary, additional measurement data at different strokes should
be taken to accurately describe the relations between operating force and pipeline pressure.
9.1.3 Pressure test at trailer pipeline joint
Motor vehicles that are allowed to be coupled to Category O3 or O4 trailers shall be tested under
the following conditions.
---Respectively at the cut-off pressure and the re-energizing pressure, disconnect the
energy supply device of the brake control system. Connect a 0.5 L air reservoir to the
control pipeline joint. Under any load conditions, actuate the parking brake and
measure the pressure at the air pressure control and energy supply pipeline joint.
---When the air reservoir is at the re-energizing pressure, DO NOT actuate the service
brake and measure the pressure of the energy supply pipeline.
When electrical control circuits are provided, measure whether the corresponding digital
command is issued when the service brake system control device is actuated at full stroke in
accordance with ISO 11992 (all parts).
9.2 Energy Supply Device Capacity Test
9.2.1 Test data
The following data needs to be recorded during the test.
---The time (t1) required for the pressure to rise from 0 kPa to p1, measured at the energy
storage device with the slowest pressure rise;
---When the vehicle does not have an energy storage device for air pressure auxiliary
equipment, or when the total capacity of one or more energy storage devices used for
the same purpose does not exceed 20% of the total capacity of the energy storage
devices of the braking system, the time (t2) required for the pressure to rise from 0 kPa
to p2, measured at the energy storage device with the slowest pressure rise;
---When the vehicle is equipped with one or more energy storage devices for air pressure
auxiliary equipment, and the total capacity of which exceeds 20% of the total capacity
of the braking system, the time (t3) required for the pressure to rise from 0 kPa to p2,
measured at the brake energy storage device with the slowest pressure rise.
9.2.2 Measurement conditions
During the test, the air compressor speed shall be the engine’s maximum power speed or the
speed corresponding to the engine’s rated speed. During the test to determine t1 and t2, the
auxiliary equipment energy storage device shall be disconnected.
Vehicles capable of towing pneumatic brake trailers shall simulate the trailer through an energy
storage device connected to the energy supply pipeline, the capacity of which shall be calculated
in accordance with GB 12676-2014.
9.2.3 Basic test (for all vehicles)
For all vehicles, perform the test in accordance with 9.2.2 and measure the pumping times t1
and t2.
9.2.4 Basic test (for vehicles capable of towing pneumatic brake trailers)
For vehicles capable of towing pneumatic brake trailers, with a simulated trailer energy storage
device connected, perform the test in accordance with 9.2.2.Measure the pressure rising times
t1 and t2.
9.2.5 Additional test
9.2.5.1 If the volume of the energy storage device of the auxiliary equipment is greater than 20%
of the total volume of the braking system, then, an additional test shall be performed.
9.2.5.2 Separately measure the time t3 for the pressure in the auxiliary energy storage device to
reach the pressure specified by the vehicle manufacturer.
9.3 Service Brake System Response Time Test
9.3.1 Test condition
9.3.1.1 The response time of the service brake system shall be measured at the input port of the
pneumatic actuator (brake chamber, air / hydraulic conversion device) in the most unfavorable
position. During measurement, the brake clearance shall be adjusted to the minimum possible
(just enough to allow the wheels to be manually turned without brake rubbing).
9.3.1.2 If the vehicle is equipped with a control pipeline for pneumatic trailers, the response
time shall be measured at the end of a 2.5 m long, 13 mm inner diameter pipeline connected to
the trailer control pipeline joint. During the test, a container with a volume of (385 5) mL
(equal to the volume of a 2.5 m long, 13 mm inner diameter pipe at a pressure of 0.65 MPa)
shall be connected to the energy supply joint. If the traction vehicle has an electrical control
circuit, then, the response time of the digital control value shall also be measured in accordance
with ISO 11992 (all parts).
9.3.1.3 At the beginning of each test, the pressure in all air reservoirs shall be the minimum
pressure of the system.
9.3.1.4 If the vehicle is equipped with a load sensing device, the test shall be conducted with
the vehicle fully loaded.
9.3.2 Test procedures
9.3.2.1 The relations between the response time and the actuation time shall be determined by
a series of at least five braking operations at full stroke, starting with the shortest actuation time
and gradually increasing to an actuation time of approximately 0.4 s.
9.3.2.2 The measured results shall be rounded to the nearest 0.1 s, and a curve of the measured
response times shall be drawn.
9.3.2.3 The time value corresponding to an actuation time of 0.2 s obtained through the
interpolation method in the curve is the response time, which is rounded to the nearest 0.1 s.
9.3.2.4 For semi-trailer towing vehicles, the length and inner diameter of the connecting hose
shall be recorded.
9.3.2.5 Record the time it takes from actuation of the brake pedal to the following conditions.
---The pressure measured at the pneumatic actuator in the most unfavorable position
reaches 75% of the maximum steady-state pressure;
---The pressure measured at the connection of the pneumatic trailer control pipeline
reaches 10% and 75% of the target value;
---When an electrical control circuit is present, the digital command value measured in
accordance with ISO 11992 (all parts) reaches 10% and 75% of the target value.
9.3.3 Correspondence between pneumatic and electrical control circuit signals
Actuate the service brake and generate an electrical control circuit signal equivalent to 0.11
MPa. Check whether the pneumatic control pipeline can detect the corresponding air pressure
control signal within 1 second.
9.4 Automatic Brake Test
To verify whether the vehicle can automatically brake in the event of a fault of the trailer control
pipeline, the following test shall be performed at maximum energy supply pipeline pressure.
Simulate a rupture in the trailer control pipeline at the connection between the towing vehicle
and trailer. Actuate the service brake system control device at full stroke. Check and record the
time it takes for the pressure at the end of a 2.5 m long, 13 mm inner diameter pipeline connected
to the energy supply pipeline joint to drop below 0.15 MPa after the brake pedal is actuated.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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