QC/T 239-2015Technical requirements and bench test methods for service brakes of commercial vehicles (English PDF)
商用车辆行车制动器技术要求及台架试验方法
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Issued by
MIIT
Level / Type
Industry · Recommended
Issue date
April 30, 2015
Implementation date
October 1, 2015
Scope
QC/T 239-2015 is the English-translated version of 商用车辆行车制动器技术要求及台架试验方法.
QC/T 239-2015 covers the service brake assembly of a commercial vehicle: terms, performance requirements and bench test methods. Clause 1 applies it to brake and friction lining (brake block) assemblies for categories M2, M3 and N of GB/T 15089, and lets category O brakes refer to it.
Clause 4 fixes the pass marks: a fade rate between -20% and 40% in the first fade test and between -20% and 60% in the second, a recovery rate whose absolute value stays within 20%, braking noise below 80 dB(A) for M2, M3 and N1 samples and below 85 dB(A) for the others, and an average braking torque within ± 15% of its pre-wear value.
Clause 5 wants an inertia bench with line pressure rates of (1.5 ± 0.3) MPa/s for pneumatic brakes and (25 ± 5) MPa/s for hydraulic ones, cooling air at 11 m/s and control errors within ± 3%.
Issued by MIIT on 30 April 2015, it replaces QC/T 239-1997 and has applied since 1 October 2015.
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Document preview — QC/T 239-2015
National Standard of the People's Republic of China
- Replacing
- QC/T 239-1997
Issued by: Ministry of Industry and Information Technology of the People's Republic of China
Contents
- Foreword
- 1 Scope
- 2 Normative References
- 3 Terminologies and Definitions
- 4 Performance Requirements
- 5 Relevant Requirements for Test
- 6 Test Preparation
- 7 Test Methods and Conditions
- Appendix A (Normative) Evaluation Method of Braking Torque
1 Scope
This standard specifies the terminologies and definitions, performance requirements as well as bench test methods of commercial vehicle service brake assembly.
This standard applies to the service brake assembly for Categories M2, M3 and N vehicles specified in GB/T 15089 as well as friction lining (brake block) assembly. The brake assembly for Category O vehicles may also refer to the provisions of this standard.
2 Normative References
The following documents for the application of this document are essential. Any dated reference, just dated edition applies to this standard. For undated references, the latest edition (including any amendments) applies to this standard.
GB/T 5620 Road Vehicles - Braking of Automotive Vehicles and Their Trailers - Vocabulary
GB/T 15089 Classification of Power - Driven Vehicles and Trailers
QC/T 556 Automotive Brake - Temperature Measurement and Thermocouple Attachment
3 Terminologies and Definitions
For the purposes of this standard, the terminologies and definitions specified in GB/T 5620 and the following ones apply.
3.1 Braking period
The time from stating a braking to the next braking in a continuous braking procedure.
4 Performance Requirements
4.1.3.3 The variation trend of the average braking torque at each initial braking speed along with brake pressure shall be stable, and shall be free from jumping.
4.1.4 The first fade recover test.
4.1.4.1 Tested according to 7.1.7, the fade rate of its sample shall be within the scope of -20 % ~ 40%, and the absolute value of the recover rate shall not be larger than 20%.
4.1.4.2 The average braking torque value of thermal braking efficiency test shall not be less than 60% of that under the equivalent conditions in the second efficiency test.
4.1.4.3 At the end of the test, brake shall work normally, and shall not have obvious dragging.
4.1.5 The third efficiency test. The same as 4.1.3.
4.1.6 The second fade test.
4.1.6.1 Tested according to 7.1.11, the fade rate of its sample shall be within the scope of -20% ~ 60%.
4.1.6.2 The average braking torque value of thermal braking efficiency test shall not be less than 40% of that under the equivalent conditions in the third efficiency test.
4.1.6.3 At the end of the test, the brake shall work normally, and shall not have obvious dragging; brake drum or brake disc friction surface shall be free from obvious scratch and crack.
4.1.7 The second normal temperature efficiency test.
The average braking torque value of sample under the specified braking pressure shall not be less than 75% of the average braking torque value under the same braking pressure in the fourth efficiency test.
4.1.8 The fourth efficiency test. The same as 4.1.3.
4.1.9 Braking noise requirements
During the test process in 7.1, when measurement is conducted according to 5.2.4, the braking noise of the samples for Categories M2, M3 and N1 vehicles shall be less than 80dB (A), while that of the samples for other categories shall be less than 85dB(A).
4.1.10 Requirements of samples after test
After the test specified in 7.1, the brake shall work normally and shall meet the following requirements.
a) The working surface of brake drum or brake disc shall be free from obvious scratch;
b) Brake backing plate or brake caliper shall be free from any deformation affecting the braking performance;
c) Friction lining (brake block) surface shall be complete, free from defects such as obvious missing edge, blistering, pit, peeling, cracking, scratch and burn, slight cracks are allowed;
d) Friction lining (brake block) and brake shoe (backboard) shall be free from segregation;
e) Brake cylinder brake caliper shall be free from leakage.
4.2 Brake wear test
4.2.1 Wear requirements
4.2.1.1 The wear requirements for brake friction lining (brake block) and brake drum (disc) shall be subject to negotiation between supplier and purchaser.
4.2.1.2 After the whole wear test is finished, friction lining (brake block) and brake drum (disc) shall meet the following requirements.
a) The working surface of brake drum or brake disc shall be free from obvious scratch;
b) Friction lining (brake block) surface shall be complete, free from defects such as obvious missing edge, blistering, pit, peeling and cracking;
c) Friction lining (brake block) and shoe (backboard) shall be free from separation;
d) Friction lining (brake block) surface shall be free from any crack penetrating the whole friction surface.
4.2.2 Braking efficacy inspection
Compared with that before wear test, the average braking torque variation under the specified braking pressure shall not exceed ±15%.
5 Relevant Requirements for Test
5.1 Test equipment requirements
5.1.1 The test equipment is inertia brake test bench (both single-wheel and double-wheel are allowed), its performance index shall meet the requirements of all tests in this standard.
5.1.2 The brake pressure supply system of test equipment shall meet the requirements of braking pressure under various braking conditions and shall remain stable. The pressure rise and reduction rate of brake line shall meet the following requirements.
a) It shall be (1.5±0.3) MPa/s for pneumatic brake;
b) It shall be (25±5) MPa/s for hydraulic brake.
5.1.3 The brake cooling system of test equipment shall make the wind speed at the tested brake reach 11m/s, and cover the whole brake assembly.
5.1.4 The control error of braking pressure, braking torque and rotation speed of test bench main shaft shall not be larger than ±3%. The relative error of rotational inertia (including the inertia of test bench rotating part) shall not be larger than ±5%.
5.1.5 The test equipment shall be able to continuously record the following parameters, and the measuring error shall meet the following requirements.
a) It shall be ±1.5% for output torque;
b) It shall be ±1.5% for braking pressure;
c) It shall be ±1.5% for the rotation speed of test bench main shaft;
d) It shall be ±0.01s for the braking time;
e) It shall be ±3°C when the brake drum (disc) or friction lining (brake block) temperature is below ±3°C, and ±1% when the temperature is higher than 300°C.
5.1.6 The device and thermocouple used for measuring the temperature of brake drum (disc) or friction lining (brake block) shall meet the relevant requirements of QC/T 556.
5.1.7 For the instruments or meters indicating various parameters, the accuracy grade shall not be lower than Grade 2.5.
5.2 Other requirements
5.2.1 All test speeds shall be rounded off to the integral multiple of 5.
5.2.2 Except for fade test and unless otherwise specified, the test cooling air velocity shall be 11 m/s, and the temperature of cooling air shall be the room temperature.
7 Test Methods and Conditions
7.1.8 The third running-in test. The same as 7.1.6.
7.1.9 The third efficiency test. The same as 7.1.5.
7.1.10 The fourth running-in test. The same as 7.1.6.
7.1.11 The second fade test.
7.1.11.1 The brake drum (or brake disc) rotates at the constant speed of 30 km/h (40 km/h for Category N1 and Category M2 vehicles), then cycling brake test is conducted, for which a test period is braking 12 s, and braking off 18 s. The brake control mode is invariable output mode, the output braking torque is corresponding to the braking deceleration of 0.7m/s².In the braking process, the speed fluctuation of brake drum (or brake disc) shall not exceed ±5% of the test speed.
7.1.11.2 The initial braking temperature during the first braking is (40±5) °C. The test bench cooling device is closed before the first braking. In the test process, its dedusting system may be started in order to discharge the smoke generated in the test, however, the maximum wind velocity shall not exceed 3m/s.
7.1.11.3 The total braking times is 60.
7.1.11.4 After the end of the last braking (brake off), the test bench cooling system shall be started without delay to cool the test piece, simultaneously, its drive device is started, 60 s later, the thermal braking efficiency test is conducted once according to the following conditions.
a) For Category N1 vehicles, the initial braking speed is 80 km/h; for other categories of vehicles, it is 60 km/h;
b) The braking pressure is that specified for braking torque assessment in efficiency test or corresponding to braking deceleration of 5.0 m/s².
7.1.11.5 At the end of the test, open test bench cooling device, make the brake rotate at a low speed until its temperature approximates the room temperature, then inspect the brake's dragging condition. Inspect the friction lining (brake block) for cracks, carbon deposit, scorch or bright film on the surface; inspect the friction surface of brake drum (disc) for scratch or cracks, etc.
7.1.11.6 Record the initial braking speed, initial braking temperature, braking final temperature, braking time, braking pressure and output braking torque of each braking.
Observe and record the times of braking when scorch, smoke and other abnormal phenomena occur on the friction lining (brake block) in the process of fade test; for hydraulic brake, record the times of braking when air resistance occurs, and the temperature of friction lining (brake block) during air resistance.
7.1.11.7 If the test equipment can't be tested according to the above method, the following alternatives may be adopted, but shall be noted in the report.
a) For Category M2 and Category N1 vehicles, the initial braking speed is 56 km/h; for other categories of vehicles, it is 50 km/h;
b) For Category M2 and Category N1 vehicles, the final speed of braking is 27 km/h; for other categories of vehicles, it is 25 km/h;
c) Braking pressure is corresponding to braking deceleration of 3.0 m/s²;
d) Braking period is 30s;
e) The initial braking temperature during the first braking is (40±5) °C;
f) Braking times is 60.
7.1.12 The fifth running-in test. The same as 7.1.6.
7.1.7.3 Thermal braking efficiency test
a) After the end of the last braking in the fade test (speed is reduced to zero), the test bench cooling system is started without delay to cool the test piece, simultaneously, its drive device is started, 60 s later, the thermal braking efficiency test is conducted according to the following conditions.
1) For Category N1 vehicles, the initial braking speed is 80 km/h; for other categories of vehicles, it is 60 km/h;
2) Braking pressure is that specified for braking torque assessment in efficiency test or corresponding to braking deceleration of 5.0 m/s².
b) At the end of the test, the brake drum (disc) rotates at the initial braking speed in the recover test, 180s later, the first braking is conducted.
7.1.7.4 Recover test
a) For Category N1 and Category M2 vehicles, the initial braking speed is 50 km/h; for other categories of vehicles, it is 30 km/h.
b) The braking pressure is the same as that in the reference test.
c) The braking period is 60 s.
d) The braking times is 15.If the initial braking temperature of the last recover test is higher than 100°C, braking times may be added, however, the total braking times shall not be larger than 20.
7.1.7.5 Test record and inspection after test
a) Record the initial braking speed, initial braking temperature, braking final temperature, braking time, braking pressure and output braking torque of each braking.
Observe and record the times of braking when scorch, smoke and other abnormal phenomena occur on friction lining (brake block) in the process of fade test; for hydraulic brake, record the times of braking when air resistance occurs, and the temperature of friction lining (brake block) during air resistance.
b) At the end of the test, the friction lining (brake block) shall be inspected for cracks, carbon deposit, scorch or bright film on the surface; the friction surface of brake drum (disc) shall also be inspected for scratch or cracks, etc.
7.1.13 The second normal temperature efficiency test
The same as 7.1.4.
7.1.14 The fourth efficiency test
The same as 7.1.5.
7.1.15 Final inspection
At the end of the test in 7.1.14, the brake is cooled to the room temperature, then the following inspection and record shall be conducted.
a) Inspecting the surface of friction lining (brake block) for cracks, blistering, pit, cracking, peeling, scratch, carbon deposit or burn;
b) Inspecting the friction lining (brake block) and braking shoe (backboard) for […]
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 25 pages — is available in the English PDF.
Referenced standards
Normative references
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Editions of QC/T 239
| Edition | Title | Revision | Status |
|---|---|---|---|
| QC/T 239-2015 | Technical requirements and bench test methods for service brakes of commercial vehicles | current edition | Current |
| QC/T 239-1997 | Technical requirements and bench test methods for service brakes of commercial vehicles | previous edition | Superseded |
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Related Standards
GB/T 15089-2001 — Classification of power-driven vehicles and trailers
GB/T 5620-2020 — Road vehicles - Vocabulary and definition for braking of automotive vehicles and their trailers
QC/T 556-1999 — Automotive brakes - Temperature measurement and thermocouple installation
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