Some standard content:
Mechanical Industry Standard of the People's Republic of China
Tire Loader Brake
Bench Test Method
Subject Content and Scope of Application
IB/T 7149
This standard specifies the test items, test conditions, test methods and procedures, test reports, etc. for the bench test of tire loader service brakes.
This standard applies to the performance inspection of the tire loader service brake assembly (hereinafter referred to as the brake) with a machine weight (operating weight) greater than 1.5t. Other tire-type engineering machinery can also refer to it. 2 Reference Standards
JB3936 Automobile Brake Temperature Measurement and Thermocouple Installation 3 Test Items
Brake Effectiveness Test;
Brake Thermal Decay and Recovery Test:
Brake Lining (Pad) Wear Test.
4 Test Conditions
4.1 The brake under test shall comply with the requirements of the product drawings and technical documents. 4.2 Test equipment
Inertia test bench (single-end and double-end) and measuring and recording instruments. 4.3 Instruments and their accuracy requirements
Instruments that indicate and record braking torque, braking temperature, braking distance, braking time, brake line pressure and test bench shaft speed. The accuracy requirement should not be greater than ±2% of the full scale of the instrument. 4.4 The limit deviation of the pressure of the brake line fluid and the brake temperature is ±5%; the limit deviation of the test bench shaft speed is ±2%, and the moment of inertia should include the inertia of the rotating part of the test bench, and its limit deviation is ±5%. 4.5 Brake temperature measurement
During the braking process, the temperature of the brake drum (disc) and brake lining (pad) should be measured and recorded. The measurement method and the sensor used should comply with the provisions of JB3936.
4.6 Cooling conditions
The test is carried out under room overflow conditions, and the brake is cooled by a ventilator. 5 Test method and procedure
5.1 Test preparation
5.1.1 Clean the surface of the brake lining (pad) with solvent. 5.1.2 Measure the thickness of the brake lining (pad) and weigh it. Measure at least 3 points for each brake lining (pad). The maximum pressure point must be included. Use a diagram to indicate the specific location of the measuring point. 5.1.3 According to the required test vehicle speed, calculate the corresponding speed value of the brake drum (disc) shaft installed on the test bench according to formula (1). n=2.65 -
Where: n---installed brake drum (disc) shaft speed, r/min; V
·test vehicle speed, km/h;
-~tire rolling radius, m.
5.1.4 Calculate the flywheel count (rotational inertia calculation) used on the test bench based on the inertial load borne by the brake. 5.1.4.1 When the brakes of both front wheels are tested simultaneously, calculate according to formula (2). Iu*-Gipr\.
Wuzhong: l…
-Moment of inertia of both front wheels when brakes are tested simultaneously, N·m2; front axle load at unloaded transport position, N;
front axle load transfer coefficient during unloaded braking, calculated as follows: β1+4
Where: Zhong-road adhesion coefficient;
height of center of gravity at unloaded transport position, m;
-distance from center of gravity to rear axle, m.
5.1.4.2When only single front wheel brake test is performed, calculate according to formula (3). Ir
Wu Zhong:
Moment of inertia when testing only the single front wheel brake, N·m (1)
(2)
5.1.5Install the brake under test on the inertia test bench and adjust the clearance between the brake lining (pad) and the brake drum (disc) according to the product drawing. 5.1.6Check the sealing condition of each joint and drain the air from the hydraulic pipeline and the brake wheel cylinder. 5.2 First running-in
Make the contact area between the brake lining (pad) and the brake drum (disc) reach more than 80%. 5.2.1 Test method
5.2.1.1 Initial braking speed 30km/h.
Adjust the pipeline pressure so that the deceleration reaches 0.30g, and brake from the initial braking speed to the final speed of zero. 5.2.1.21
5.2.1.3 Adjust the fan speed so that the initial temperature of the brake drum (disc) is controlled below 70C each time. 5.2.1.4 The number of running-in times is determined by obtaining the required contact area. Note: The contact area can be obtained by hand grinding and by grinding the brake drum (disc) temperature. 5.3 The first performance test
Measure the output braking torque value of the brake after running-in. 5.3.1 Test method
5.3.1.1 The initial braking speed is specified as 10, 20, 30, 40, 50 kg/h (each increase of 10 km/h is a level) to the maximum vehicle speed. 5.3.1.2 The pipeline pressure is specified as 4.9~~11.8 MFa (each increase of 0.98 MPa is a level). 5.3.1.3 The number of brakes is one at each initial braking speed, and one at each line pressure, from the initial braking speed to the final speed of zero. 5.3.1.4 The initial braking temperature is controlled at 70°C ± 5°C. 5.3.2 Measurement items
Record the initial braking speed, arm pressure, output braking torque, brake drum (disc) temperature and braking time for each braking. 5.4 The first thermal decay and recovery test
Check the performance decay of the brake during multiple continuous uses and its recovery ability after cooling. 5.4.1 Reference point inspection
5.4.1.1 The initial braking speed is 20k.m/h.
JB/T 7149-93
5.4.1.2 Adjust the line pressure so that the deceleration reaches 0.30g, from the initial braking speed to the final speed of zero, 5.4.7.3 The initial braking temperature is below 70°C.
5.4.1.4 Brake 3 times.
5.4.2 Thermal decay test
5.4.2.1 Initial braking speed 40km/h.
5.4.2.2 Adjust the line pressure so that the deceleration reaches 0.45+ from the initial braking speed to the final speed of zero. 5.4.2.3 Initial braking temperature 70C±5, turn off the fan. 5.4.2.4 Brake 15 times
5.4.2.5 Braking cycle 60s.
5.4.2.6 After the decay test, the brake drum (disc) runs at a speed equivalent to 20km/h, turn on the fan, cool at a wind speed of 10m/s for 3 minutes, and then start the recovery test.
5.4.3 Recovery test
5.4.3.1 Initial braking speed 20km/h.
5.4.3.2 Adjust the pipeline pressure to make the deceleration reach 0.30%. 5.4.3.3 Cool the brake during the whole test at a wind speed of 10m/s. 5.4.3.4 Brake 10 times.
5.4.3.5 Brake cycle 60s
5.4.4 Performance point inspection
5.4.4.1 Braking initial speed 40km/h.
5.4.4.2 Adjust the pipeline pressure to make the deceleration reach 0.45g. 5.4.4.3 Brake initial temperature 70C±5℃C.
5.4.4.4 Brake 3 times.
5.4.4.5 Measurement items
5.4.5 Reference point inspection, thermal decay test, recovery test and performance point inspection. Each time the brake is applied, the initial braking speed, line pressure J, output braking torque, brake drum (disc) temperature, brake lining (pad) temperature and braking time shall be recorded. 5.5 Second performance test
Performance changes after the first decay and recovery test. Check the brake after the second
5.5.1 Test method shall be in accordance with the provisions of Article 5.3.1, and 5.5.2 Measurement item diagram shall be in accordance with the provisions of Article 5.3.2. 5.6 Second thermal decay test
Check the performance decay of the brake under low line pressure (deceleration) when used for a long time. 5.6.1 Test method
5.6.1.1 Initial braking speed 20km/h.
5.6.1.2 Adjust the line pressure so that the deceleration is 0.07g. 5.6.1.3 Braking time
a. Each dragging time: 40s for hydraulic type and 12s for pneumatic type. b. Drag-off time: 605 for hydraulic type and 18s for pneumatic type, total test time 1800s. 5.6.1.4 Initial brake temperature: The brake temperature is room temperature during the first dragging. 5.6.1.5 Cooling: Turn off the fan during the entire test. 5.6.2 Measurement items
Record the line pressure, output braking torque, brake drum (disc) temperature, brake lining (pad) temperature and brake oil temperature in the brake wheel cylinder for each braking. Observe and record the lining (pad) to see whether it emits a burning smell or produces smoke during braking. 292
5.6.3 Appearance inspection
JB/T 7149—93
After the test, turn on the ventilator and let the brake run at low speed to room temperature. Check the condition of the brake lining (pad), such as cracks, carbon deposits, burning and surface bright film.
If it is an oil-type brake, continue to record the rise value of the brake oil temperature after the test stops until it reaches the highest value, and record the time to reach the highest value.
5.7 Second running-in
Eliminate the bright film on the brake lining (pad) and a certain degree of carbon deposits on the brake lining (pad) in the second fading test. The test method is in accordance with the provisions of Article 5.2.1, but the number of braking times is 50 times. 5.8 Second performance test
Check the changes of the brake after the second fading test and the second running-in test. 5.8.1 The test method is in accordance with the provisions of Article 5.3.1. 5.8.2 The measurement items are in accordance with the provisions of Article 5.3.2. 5.9 Brake wear test (optional) Measure the wear of the brake lining (pad). 5.9.1 Test method
5.9.1.1 The thickness of each selected point of the brake lining (pad) is accurately measured with an accuracy of 0.01mm. The initial speed of the first braking is 10km/h, the initial temperature of the brake is 60℃±10℃, and the number of braking times is 500. 5.9.1.2
5.9.1.3 The initial speed of the second braking is 20km/h, the initial temperature of the brake is 85℃±10℃, and the number of braking times is 300. 5.9.1.4 The initial speed of the third braking is 40 km/h, and the initial temperature of the brake is 140°C ± 10°C. The number of braking times is 100. 5.9.1.5 Adjust the input pipeline pressure to make the deceleration reach 0.30g, and brake from the initial braking speed to the final speed of zero. 5.9.1.6 Use a fan to cool and maintain the required initial braking temperature. 5.9.2 Measurement items
In the first test, measure the thickness of the selected points of the brake lining (pad) and calculate the total wear of the brake lining (pad). 6 Test report
The vehicle parameters and brake parameters are shown in Table A1 of Appendix A (lining filling parts): a.
b. The results of the first (second) running-in test are filled in Table A2 of Appendix A; c. The results of the second and third performance tests are filled in Table A3 of Appendix A, and the performance curve is drawn in Figure A1: d. The results of the first thermal decay, recovery test and the second thermal decay test shall be filled in Table A4 of Appendix A, and the first thermal decay, recovery curve shall be drawn in Figure A2, and the second thermal decay curve shall be drawn in Figure A3. e. The results of the first (second and third) wear test shall be filled in Table A5 of Appendix A. 7 Definitions of terms and codes
The definitions of terms and codes are shown in Appendix B (reference). 293
Production
Machine weight in loaded transport state
Axle load distribution: empty transport position, front
Fully loaded transport position, front
Height of center of gravity: when empty transport position
JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake manufacturer
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of sale
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay test Table A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installation Brake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) drawn during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as ordinate and time as abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time when the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes: bzxz.net
This standard was proposed and managed by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.3 Appearance inspection
JB/T 7149—93
After the test, turn on the ventilator and run the brake at low speed to room temperature. Check the condition of the brake lining (pad), such as cracks, carbon deposits, scorch and surface bright film.
For oil-type brakes, after the test is stopped, continue to record the rise in brake oil temperature until it reaches the highest value, and record the time when it reaches the highest value.
5.7 Second running-in
Eliminate the bright film on the brake lining (pad) and a certain degree of carbon deposit on the brake lining (pad) in the second fading test. The test method is in accordance with the provisions of Article 5.2.1, but the number of braking times is 50. 5.8 Second performance test
Check the changes of the brake after the second fading test and the second running-in. 5.8.1 The test method is in accordance with the provisions of Article 5.3.1. 5.8.2 Measurement items shall be in accordance with the provisions of Article 5.3.2. 5.9 Brake wear test (optional) Measure the wear of the brake lining (pad). 5.9.1 Test method
5.9.1.1 Accurately measure the thickness of each selected point of the brake lining (pad) with an accuracy of 0.01mm. The initial speed of the first braking is 10km/h, the initial temperature of the brake is 60℃±10℃, and the number of braking times is 500. 5.9.1.2
5.9.1.3 The initial speed of the second braking is 20km/h, the initial temperature of the brake is 85℃±10℃, and the number of braking times is 300. 5.9.1.4 The initial speed of the third braking is 40km/h, the initial temperature of the brake is 140℃±10℃. The number of braking times is 100. 5.9.1.5 Adjust the input pipeline pressure to make the deceleration reach 0.30g, brake from the initial braking speed to the final speed of zero, 5.9.1.6 Use a fan to cool and maintain the required initial braking temperature. 5.9.2 Measurement items
First test, measure the thickness of the selected points of the brake lining (pad), and calculate the total wear of the brake lining (pad). 6 Test report
See Appendix A (lining filling parts) Table A1 for vehicle parameters and brake parameters: a.
b. The results of the first (second) running-in test are filled in Appendix A Table A2; c. The results of the first (second and third) performance test are filled in Appendix A Table A3, and the performance curve is drawn in Figure A1: d. The results of the first heat decay, recovery test and the second heat decay test are filled in Appendix A Table A4, and the first heat decay, recovery curve is drawn in Figure A2, and the second heat decay curve is drawn in Figure A3. e. The results of the second and third wear tests shall be filled in Table A5 of Appendix A. 7 Definitions of terms and codes See Appendix B (reference) for definitions of terms and codes. 293 Production Machine weight in loaded transport state Axle load distribution: unloaded transport position, front Fully loaded transport position, front Center of gravity height: unloaded transport position JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake manufacturer
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of sale
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay test Table A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installation Brake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.3 Appearance inspection
JB/T 7149—93
After the test, turn on the ventilator and run the brake at low speed to room temperature. Check the condition of the brake lining (pad), such as cracks, carbon deposits, scorch and surface bright film.
For oil-type brakes, after the test is stopped, continue to record the rise in brake oil temperature until it reaches the highest value, and record the time when it reaches the highest value.
5.7 Second running-in
Eliminate the bright film on the brake lining (pad) and a certain degree of carbon deposit on the brake lining (pad) in the second fading test. The test method is in accordance with the provisions of Article 5.2.1, but the number of braking times is 50. 5.8 Second performance test
Check the changes of the brake after the second fading test and the second running-in. 5.8.1 The test method is in accordance with the provisions of Article 5.3.1. 5.8.2 Measurement items shall be in accordance with the provisions of Article 5.3.2. 5.9 Brake wear test (optional) Measure the wear of the brake lining (pad). 5.9.1 Test method
5.9.1.1 Accurately measure the thickness of each selected point of the brake lining (pad) with an accuracy of 0.01mm. The initial speed of the first braking is 10km/h, the initial temperature of the brake is 60℃±10℃, and the number of braking times is 500. 5.9.1.2
5.9.1.3 The initial speed of the second braking is 20km/h, the initial temperature of the brake is 85℃±10℃, and the number of braking times is 300. 5.9.1.4 The initial speed of the third braking is 40km/h, the initial temperature of the brake is 140℃±10℃. The number of braking times is 100. 5.9.1.5 Adjust the input pipeline pressure to make the deceleration reach 0.30g, brake from the initial braking speed to the final speed of zero, 5.9.1.6 Use a fan to cool and maintain the required initial braking temperature. 5.9.2 Measurement items
First test, measure the thickness of the selected points of the brake lining (pad), and calculate the total wear of the brake lining (pad). 6 Test report
See Appendix A (lining filling parts) Table A1 for vehicle parameters and brake parameters: a.
b. The results of the first (second) running-in test are filled in Appendix A Table A2; c. The results of the first (second and third) performance test are filled in Appendix A Table A3, and the performance curve is drawn in Figure A1: d. The results of the first heat decay, recovery test and the second heat decay test are filled in Appendix A Table A4, and the first heat decay, recovery curve is drawn in Figure A2, and the second heat decay curve is drawn in Figure A3. e. The results of the second and third wear tests shall be filled in Table A5 of Appendix A. 7 Definitions of terms and codes See Appendix B (reference) for definitions of terms and codes. 293 Production Machine weight in loaded transport state Axle load distribution: unloaded transport position, front Fully loaded transport position, front Center of gravity height: unloaded transport position JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake production"
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of sale
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay testTable A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.9 Brake wear test (optional) Measure the wear of the brake lining (pad). 5.9.1 Test method
5.9.1.1 Accurately measure the thickness of each selected point of the brake lining (pad) with an accuracy of 0.01mm. The initial speed of the first braking is 10km/h, the initial temperature of the brake is 60℃±10℃, and the number of braking times is 500. 5.9.1.2
5.9.1.3 The initial speed of the second braking is 20km/h, the initial temperature of the brake is 85℃±10℃, and the number of braking times is 300. 5.9.1.4 The initial speed of the third braking is 40km/h, the initial temperature of the brake is 140℃±10℃. The number of braking times is 100. 5.9.1.5 Adjust the input pipeline pressure so that the deceleration reaches 0.30g, and brake from the initial braking speed to the final speed of zero. 5.9.1.6 Use a fan to cool and maintain the required initial braking temperature. 5.9.2 Measurement Items
In the first test, measure the thickness of the selected points of the brake lining (pad) and calculate the total wear of the brake lining (pad). 6 Test Report
The vehicle parameters and brake parameters are shown in Table A1 of Appendix A (lining parts): a.
b. The results of the first (second) running-in test are filled in Table A2 of Appendix A; c. The results of the first (second and third) performance test are filled in Table A3 of Appendix A, and the performance curve is drawn in Figure A1: d. The results of the first (second and third) thermal decay test are filled in Table A4 of Appendix A, and the first thermal decay and recovery curves are drawn in Figure A2, and the second thermal decay curves are drawn in Figure A3. e. The results of the first (second and third) wear test are filled in Table A5 of Appendix A. 7 Definitions of Terms and Codes
The definitions of terms and codes are shown in Appendix B (reference parts). 293
Production
Machine weight in loaded transport state
Axle load distribution: unloaded transport position, front
Fully loaded transport position, front
Height of center of gravity: unloaded transport position
JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake production"
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of manufacture
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay testTable A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.9 Brake wear test (optional) Measure the wear of the brake lining (pad). 5.9.1 Test method
5.9.1.1 Accurately measure the thickness of each selected point of the brake lining (pad) with an accuracy of 0.01mm. The initial speed of the first braking is 10km/h, the initial temperature of the brake is 60℃±10C, and the number of braking times is 500. 5.9.1.2
5.9.1.3 The initial speed of the second braking is 20km/h, the initial temperature of the brake is 85℃±10℃, and the number of braking times is 300. 5.9.1.4 The initial speed of the third braking is 40km/h, the initial temperature of the brake is 140℃±10C. The number of braking times is 100. 5.9.1.5 Adjust the input pipeline pressure so that the deceleration reaches 0.30g, and brake from the initial braking speed to the final speed of zero. 5.9.1.6 Use a fan to cool and maintain the required initial braking temperature. 5.9.2 Measurement Items
In the first test, measure the thickness of the selected points of the brake lining (pad) and calculate the total wear of the brake lining (pad). 6 Test Report
The vehicle parameters and brake parameters are shown in Table A1 of Appendix A (lining parts): a.
b. The results of the first (second) running-in test are filled in Table A2 of Appendix A; c. The results of the first (second and third) performance test are filled in Table A3 of Appendix A, and the performance curve is drawn in Figure A1: d. The results of the first thermal decay, recovery test and the second thermal decay test are filled in Table A4 of Appendix A, and the first thermal decay, recovery curve is drawn in Figure A2, and the second thermal decay curve is drawn in Figure A3. e. The results of the first (second and third) wear test are filled in Table A5 of Appendix A. 7 Definitions of Terms and Codes
The definitions of terms and codes are shown in Appendix B (reference parts). 293
Production
Machine weight in loaded transport state
Axle load distribution: unloaded transport position, front
Fully loaded transport position, front
Height of center of gravity: unloaded transport position
JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake manufacturer
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of sale
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay test Table A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installation Brake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.The results of the second and third wear tests shall be filled in Table A5 of Appendix A. 7 Definitions of terms and codes See Appendix B (reference) for definitions of terms and codes. 293 Production Machine weight in loaded transport state Axle load distribution: unloaded transport position, front Fully loaded transport position, front Center of gravity height: unloaded transport position JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake production"
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of manufacture
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay testTable A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.The results of the second and third wear tests shall be filled in Table A5 of Appendix A. 7 Definitions of terms and codes See Appendix B (reference) for definitions of terms and codes. 293 Production Machine weight in loaded transport state Axle load distribution: unloaded transport position, front Fully loaded transport position, front Center of gravity height: unloaded transport position JB/T 7149-93
Bench test report of loader brake
(supplement)
Vehicle parameters and brake parameters
Tire model
Center of gravity: Distance from rear axle to wheelbase in unloaded transport position
Brake type: Front
Brake production"
Brake drive mode: Front
Brake cylinder diameter: Front
Maximum brake line pressure
Rated braking torque: Front
Friction material brand
Gap between friction lining (block) and brake drum (disc): Front Brake fluid brand
Run-in method
Input line pressure
Operator
Sample number
Test date
Deceleration
Maximum vehicle Speed
Output, Year and Month
Rolling Radius
When fully loaded in transport position
Distance from rear axle when fully loaded in transport position
Date of manufacture
Braking force ratio of front and rear axles
Manufacturer
Manufacturer
Table A2 The (first) time of fitting
Number of running-in
Table A3 The (second and third) time of performance test|| tt||Braking torque
Instability
Coefficient K
Operator
Brake drum
(disc) temperature
Date of manufacture
Date of manufacture
Contact area
Friction lining
(block) temperature
Brake oil
Temperature T
Distance S
Time!
Sample number
Test vehicle speed
Fading recovery
The first time
Thermal fading
Effectiveness point
Second time
Third time
M, (Nm)
JB/T 7149-93
Figure A1 First (second, =) braking efficiency curve MPa
First (second, third) thermal decay, recovery test and second thermal decay testTable A4
Deceleration
First time
Second time
Third time
M, (N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
567891011 12131415 times
The first thermal decay and recovery curve
Time t
8910 times
Sample number
Friction material
Production)
Measuring point
Wear amount
JB/T7149
Figure A3 The second thermal decay curve
The temperature of the tested parts of the brake (), the subscript is the tested parts, for example: brake drum temperature, T
A brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed when braking starts B2
Final braking speed: the speed when braking is completed. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested at the same time, the one with the highest temperature shall prevail. B4
|B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the continuous braking process ordinate on the braking torque and braking time curve (with braking torque as the ordinate and time as the abscissa) drawn during a braking process. As shown in Figure B1MamineB7Average braking torque: refers to the area enclosed by the braking torque and braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the ordinate value obtained. B8Braking time: refers to the time the brake acts. It includes the braking force growth process, the continuous braking process and the release braking processB9Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M,mxB10Drag: Braking without cutting off the input power. Additional Notes:
This standard was proposed and managed by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard were Yang Xiuwen and Wang Zhongru.(N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
56789101112131415 times
Thermal decay and recovery curve of the first time
Time t
8910 times
Sample number No.
Friction material
Production)
Measurement point
Amount of wear
JB/T7149
Figure A3 Second thermal decay curve
Temperature of the tested brake parts (), the subscript is the tested parts, for example: brake drum temperature, T
1 Brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed at the beginning of braking B2
Final braking speed: the speed at the end of braking. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested simultaneously, the one with the highest temperature B4
shall prevail.
B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) drawn during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) drawn during a braking process. As shown in Figure B1, Mamine B7 Average braking torque: refers to the area enclosed by the braking torque and the braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the vertical coordinate value obtained. B8 Braking time: refers to the time the brake is in effect. It includes the braking force growth process, the continuous braking process and the braking release process. B9 Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M, mx B10 Drag: Braking without cutting off the input power. Additional notes:
This standard was proposed and coordinated by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and the Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard are Yang Xiuwen and Wang Zhongru. 297(N·m)
Test date
Test bench installationBrake drum (disc) shaft speed
Braking torque
Instability
Coefficient K
Brake drum
(disc) temperature
Friction plate
Operator
(block) temperature
56789101112131415 times
Thermal decay and recovery curve of the first time
Time t
8910 times
Sample number No.
Friction material
Production)
Measurement point
Amount of wear
JB/T7149
Figure A3 Second thermal decay curve
Temperature of the tested brake parts (), the subscript is the tested parts, for example: brake drum temperature, T
1 Brake disc temperature
The second and third wear test
B1 Initial braking speed: the speed at the beginning of braking B2
Final braking speed: the speed at the end of braking. 4
Appendix B
Definition of terms and codes
(reference)
Test date
Drum (disc) temperature before braking
Operator,
Braking cycle: the time from the start of this braking to the start of the next braking in continuous braking. B3
Brake drum (disc) initial temperature: refers to the temperature of the brake drum (disc) when braking begins. When multiple brakes are tested simultaneously, the one with the highest temperature B4
shall prevail.
B5Maximum braking torque: refers to the maximum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) drawn during a braking process. Such as Mx in Figure B1. 296
Braking growth process
JB/T7149—93
Continuous braking process
, release measurement process
86Minimum braking torque: refers to the minimum value of the vertical axis of the continuous braking process on the braking torque and braking time curve (with braking torque as the vertical axis and time as the horizontal axis) drawn during a braking process. As shown in Figure B1, Mamine B7 Average braking torque: refers to the area enclosed by the braking torque and the braking time during the continuous braking process of a braking process, divided by the time of the continuous braking process, and the vertical coordinate value obtained. B8 Braking time: refers to the time the brake is in effect. It includes the braking force growth process, the continuous braking process and the braking release process. B9 Braking torque instability coefficient K: refers to the quotient of the minimum braking torque and the maximum braking torque, that is: K=M.min/M, mx B10 Drag: Braking without cutting off the input power. Additional notes:
This standard was proposed and coordinated by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute and the Xuzhou Engineering Machinery Bridge Box Factory. The main drafters of this standard are Yang Xiuwen and Wang Zhongru. 297
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