Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T7280-94
Test Methods for Tractor Braking System Bench Test
Published on July 18, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1995
Mechanical Industry Standard of the People's Republic of China
Test Methods for Tractor Braking System Bench Test
Subject Content and Scope of Application
This standard specifies the bench test methods and procedures for tractor service brakes and their operating mechanisms. This standard applies to the brake systems on agricultural wheeled and crawler tractors. 2 Terminology
JB/T 728094
2.1 Maximum braking torque: refers to the maximum value of the ordinate of the continuous braking process segment on the curve graph with braking torque as the ordinate and time as the abscissa during a braking process. As shown in Mumx in Figure 1 2.2 Minimum braking torque: refers to the minimum value of the ordinate of the continuous braking process segment on the curve graph with braking torque as the ordinate and time as the abscissa during a braking process. As shown in Mmin in Figure 1. 2.3 Average braking torque: refers to the ordinate value obtained by dividing the area enclosed by the braking torque and braking time by the time of the continuous braking process during a braking process. Braking torque growth time
Test items
Brake cold braking effectiveness test.
3.2 Brake thermal decay test and recovery test. Brake durability test.
Operating mechanism durability test.
Approved by the Ministry of Machinery Industry on July 18, 1994
Continuous braking time
Effective inspection time
Braking time:
Implemented on July 1, 1995
4 Test conditions
JB/T 7280--94
4.1 The brake system under test must comply with the drawings and technical documents approved according to the prescribed procedures. Before the test, fill in the relevant technical parameters of the test sample and the supporting host according to Table A1 in Appendix A (Supplement). 4.2 Use an inertial test bench.
4.3 Moment of inertia of the test bench
The moment of inertia of the test bench should be calculated based on the principle of equal kinetic energy, according to the maximum use mass of the tractor plus the equivalent correction value of the rotating part. The equivalent correction value of the rotating part is 7% of the maximum use mass. The sum of the moment of inertia of the flywheel selected on the test bench and the moment of inertia of other rotating parts of the test bench should be consistent with the calculated value, with a tolerance of 5%. When the tolerance is exceeded, the speed of the drive shaft on which the brake is installed is allowed to be adjusted according to the principle of equal kinetic energy.
4.4 The speed of the drive shaft on which the test brake is installed on the test bench should be consistent with the corresponding speed determined by the specified test vehicle speed. The tolerance is 3%. 4.5 Measurement of friction surface temperature
During the test, the dynamic temperature of the friction pair surface of the test brake should be measured. When a thermocouple is used as a temperature sensor, the diameter of the thermocouple wire is $0.3~0.5mm, the length does not exceed 1.0m, and the diameter of the hot end welding point is not greater than 2mm. The temperature sensor can be buried on the rotating or non-rotating part of the test brake, located in the middle of the working width of the friction surface or at the effective working radius and close to the maximum unit distributed pressure, and its temperature sensing contact is 1.0mm away from the friction surface. 4.6 Cooling conditions
The test is carried out at room temperature, and a ventilator is used to cool the brake. 4.7 Measurement of brake operating force
4.7.1. For mechanically operated brakes, the operating force of the brake pedal should be measured. 4.7.2 For hydraulically or pneumatically operated brakes, the pressure of the working medium in the brake oil (gas) cylinder should be measured. 5 Test preparation
5.1 Check whether the brake system under test meets the factory technical conditions and whether there are any abnormalities in each part, and clean the friction surface of the friction pair with solvent. 5.2 Install a sensor for measuring the temperature of the friction surface on the rotating or non-rotating parts of the brake, and install an oil temperature sensor in the hydraulically operated brake cylinder and in the oil pool of the wet brake. 5.3 For mechanically operated brakes, a sensor for measuring the brake pedal force should be installed. 5.4 For hydraulic or pneumatic brakes, a pressure sensor should be installed at the brake oil (gas) cylinder. 5.5 To measure the wear of the friction lining, at least two measuring points should be marked in advance according to different brake types, which must include the point with the maximum unit pressure. The measurement accuracy of the thickness of the selected point is 0.01mm. 5.6 According to the required test vehicle speed, calculate the speed of the drive shaft of the brake installed on the test bench so that the speed of the shaft can be adjusted and controlled during the test. The calculation formula is as follows:
= 2. 65 m
Where: v——specified test vehicle speed, km/h; rolling radius of the tractor drive wheel, m;
i transmission ratio between the brake drive shaft and the drive wheel; n-—speed of the drive shaft of the brake installed on the test bench, r/min. Calculate the inertia load of the test brake according to formula (2): 5.7
I mx(1 +0. 07)r
Where; The moment of inertia of the test brake.kg.·m\;s
The maximum usable mass of the tractor.kg:
JB/T7280-94
g——The number of service brakes of the tractor, generally 2. 5.8 Install the test brake and operating mechanism on the test bench, and adjust the brake clearance of the brake assembly according to the design requirements. The mechanical operating mechanism can be replaced by a hydraulic cylinder. The connection method of the hydraulic and pneumatic operating mechanisms should be consistent with the actual vehicle. Drain the air in the installed oil (gas) pipeline and the brake cylinder, and check the sealing of each connection point of the pipeline. 5.9 Check the oil level of the oil pool where the wet brake is located according to the design requirements, and check whether the test hydraulic pump station is working properly. 5.10 Preparation of test instruments
Select and adjust the test instruments according to the parameters to be measured and their range of variation, and calibrate the test quantities that need to be recalibrated. 6 Test methods and procedures
6.1 Running-in
6.1.1 The initial braking speed is 80% of the maximum design vehicle speed, and the braking end speed is zero. 6.1.2 The braking deceleration is 0.20g\.
Note; 1) g is the acceleration of gravity, the same below. 6.1.3 Turn on the ventilator and adjust the braking interval time so that the initial temperature of the brake rubbing surface before each braking is controlled below 100℃. 6.1.4 Brake 100 times under the above conditions.
6.1.5 Check the brake friction pair. If its contact area does not reach 80%, it is allowed to obtain this contact area by manual grinding and controlled brake temperature dragging. At the same time, check whether the operating mechanism has any abnormal conditions. Fill in the running-in data and inspection results according to Table A2 in Appendix A. 6.2 The first cold brake performance test
6.2.1 The initial braking speed is the maximum design vehicle speed, and the final braking speed is zero. 6.2.2 The braking deceleration is 0.1~0.5g, with each interval of 0.1g as one level or divided into five levels according to the oil (gas) pressure range or pedal force range used when the test brake is operated on the tractor, but the maximum braking torque shall not exceed the manufacturer's specifications. 6.2.3 Within the braking deceleration range, brake once for each level of deceleration. 6.2.4. The initial temperature of the friction pair surface of the brake is controlled at 65±5℃ before each braking. 6.2.5 Record the initial braking speed, input oil (gas) pipeline pressure or pedal force, output braking torque, effective braking time, friction pair surface temperature during each braking, and the oil temperature of the oil pool should also be recorded if it is a wet brake. In addition, abnormalities and sounds during the test should also be recorded. Fill in the data and draw the curve according to Table A3 and Figure A1 in Appendix A. 6.3 First brake efficiency thermal decay test
6.3.1 The initial and final braking speeds are the same as those in 6.2.1. The braking deceleration is 0.3g or the pipeline oil (gas) pressure or pedal force equivalent to the deceleration. 6.3.21
6.3.3 The initial temperature of the friction pair surface during the first braking is 65±5℃. The ventilator is turned off during the test. 6.3.4 Stop 10 times from the initial braking speed. The braking cycle is 60S: if there is no obvious decay, 5 more times can be performed. If it is a wet brake, stop 20 times from the initial braking speed. The braking cycle is 60S; if there is no obvious decay, 5 more times can be performed. 6.3.5
During the test, when the oil temperature in the oil pool is lower than 85C, oil circulation should be prohibited to prevent the brake from cooling down. 6.3.6 Record items are the same as those in 6.2.5. Fill in data and draw curves according to Table A4 and Figure A2 in Appendix A. 6.4 Braking performance recovery test
6.4.1 After the thermal decay test, the brake drive shaft is operated at a speed equivalent to a vehicle speed of 15 km/h, and the fan is turned on at the same time. After cooling for 3 minutes at a wind speed of 8 m/s, the recovery test is started. 6.4.2 The test conditions are the same as those specified in 6.3.1 to 6.3.5. 6.4.3 During the entire test process, the brake under test is cooled at a wind speed of 8 m/s.5 The second cold brake performance test
The test method and procedure are the same as those specified in Articles 6.2.1 to 6.2.5. 6.6 The second brake performance thermal decay test
6.6.1 The initial braking speed is 70% of the maximum design vehicle speed. 3
JB/T7280--94
6.6.2 Adjust the oil (gas) pressure or pedal force of the input pipeline so that the braking deceleration is maintained at 0.1g during the entire test. 6.6.3 At the beginning of the test, the initial temperature of the friction pair surface of the tested brake is 65±5℃. The ventilator is turned off during the test. When the oil temperature in the wet brake oil pool is lower than 85℃, its oil circulation is prohibited. 6.6.41
6.6.5 Each dragging test is 40s (mechanical and hydraulic), 15s (pneumatic), 80s (wet), and the dragging interval is 60s (mechanical and hydraulic), 20s (pneumatic), and 30s (wet). The total test time is 30min. 6.6.6 Record the oil (gas) pressure or pedal force of the input pipeline, the output braking torque, the surface temperature of the friction pair, the oil temperature in the brake cylinder, and the oil temperature of the oil pool of the wet brake; observe and record the number of times the friction lining (pad) emits a burning smell or smoke during dragging; the number of times air resistance occurs and the surface temperature of the friction pair when air resistance occurs. Fill in the data and draw the curve according to Table A5 and Figure A3 in Appendix A. 6.6.7 After the dragging test, turn on the ventilator to make the tested brake run at a speed equivalent to a vehicle speed of 15km/h and cool to room temperature. Disassemble the brake under test and check the cracks, carbon deposits and burnt conditions of the friction lining (pad), as well as the presence of a bright film on the surface of the friction material. 6.6.8 For hydraulically operated brakes or wet brakes, the oil temperature rise in the brake cylinder should be recorded during the cooling process after the test is stopped until the maximum temperature is reached, and the time from the test stop to the maximum temperature value should be recorded. 6.7 Second running-in
6.7.1 The running-in conditions are the same as those specified in Articles 6.1.1 to 6.1.3. 6.7.2 Brake 50 times under the above conditions. Record the results in Table A2 of Appendix A. 6.8 Third cold brake effectiveness test
The test method and procedure are the same as those specified in Articles 6.2.1 to 6.2.5. 6.9 Brake endurance test
6.9.1 The initial and final braking speeds are the same as those in Article 6.2.1. 6.9.2
The braking deceleration is equivalent to the maximum braking torque [or the maximum pedal force or the maximum oil (gas) pressure of the input pipeline. 6.9.3 The initial temperature of the friction pair surface during the first braking is lower than 100℃. During the test, turn on the fan to cool the test brake at a wind speed of 8m/s; for wet brakes, the oil in the brake should also be circulated.
6.9.5 Brake 100 times continuously at a time interval of 40s. 6.9.6 Record the test parameters of the 1st, 50th and 100th braking stops in accordance with Article 6.2.5. After 100 braking stops, let the drive shaft of the brake on the test bench run at a speed equivalent to a vehicle speed of 15km/h until the surface temperature of the friction pair is lower than 100℃.
6.9.8 Carry out 49 repeated tests according to the conditions of 6.9.1 to 6.9.7 (a total of 5000 braking times including 6.9.5). 6.9.9 Record the total number of completed braking times, the highest temperature of the friction pair surface of the brake, and calculate the average value of the three maximum braking torques recorded every 100 times and the corresponding average pedal force or average pipeline oil and gas pressure, the initial braking temperature and the final braking temperature of the friction pair surface. Fill in the data according to Table A6 in Appendix A.
6.9.10 Disassemble the brake, carefully check and record the conditions of each brake component, measure the thickness of the specified point of the friction lining (pad), and calculate the total wear of the friction lining (pad). Record the results in Table A7 in Appendix A. 6.10 Durability test of operating mechanism
Install the tested brake system on the test bench and adjust it according to the requirements of the instruction manual. During the test, make the drive shaft on which the brake is installed run at a low speed. Perform the brake operation with the pedal force corresponding to the maximum braking torque or the maximum oil (gas) pressure of the input pipeline. Brake continuously for 25×10* times with a braking cycle of 4 seconds. 6.10.4
6.10.5 During the test, if the temperature of the brake components exceeds 250°C (dry brake) or 150°C (wet brake), the braking frequency must be reduced or the fan must be turned on at a wind speed of 8m/s for cooling. 6.10.6 Record the faults during the test, the number of completed brakes, and the working status of the control mechanism according to Table A8 in Appendix A. After the test, disassemble and inspect the components of the control mechanism and record the wear, deformation, cracks, or leakage of oil (gas) pipelines and joints. 4
Maximum design speed km/h
Maximum/minimum use mass kg
JB/T-728094
Appendix A
Recording format and drawing curve format
(Supplement)
Table A1 Main parameters of the vehicle and its braking system ManufacturerbzxZ.net
Distance of center of mass from rear axle at maximum/minimum use mass Center of mass height at maximum/minimum use mass
Brake Transmission ratio between drive shaft and drive wheel shaftFront/rear wheel specifications (or track drive wheel pitch diameter)Inertia load of single brakekg·m
Brake type
Brake operation method
Brake friction material
Brake friction pair total clearance
Brake shaft (gas) cylinder diameter
Brake fluid brand
ForceN, or maximum oil (gas) pressurekPa
Designed maximum compensation force|| tt||Date of manufacture
Room temperature for running-in
Brake deceleration g
or pipeline oil (gas) pressure
or plate force N
Number of brakes
Contact area of friction pair %
Factory date
First (second) running-in
Operator
Test date
Sample number
Test vehicle speed
Sample number||tt ||Test vehicle speed
Operator
Deceleration g
JB/T7280-94
First (second, third) cold brake performance test month
Or input pipeline pressure kPa
Or pedal force N
Braking torque
Operator
Friction pair
Surface temperature
Brake (cooling)
Maximum oil temperature
Deceleration g
First (second, third) cold brake effectiveness test Table A4 First thermal decay test and recovery test Test date
Deceleration g
or input line pressure
or pedal force
Test bench drive shaft speed
Braking torque
Friction pair surface
Maximum temperature
Brake oil
Maximum temperature
Braking time||tt| |Braking time
Sample number
Test vehicle speed
Operator
Deceleration
JB/T7280—94
Number of tests
First thermal decay test and recovery test
Second thermal decay test
Test date
Test bench drive shaft speed
Input pipeline pressure kPa
Or pedal force N
Friction pair surface
Maximum temperature
Brake oil
Maximum overflow
Test times
Second thermal decay test
Braking time
Sample number
Test end date
Test vehicle speed
Total number of brakes
Operator
Deceleration
Or input line pressure
Or pedal force N||tt| |1st time
50th time
100th time
Sample number
Friction material
Initial temperature of friction pair before braking
Measuring point
Loss of friction
Sample number
Test start date
Operating mechanism type
Number of completed tests
Operating mechanism working status
Additional remarks:
JB/T 728094
Brake endurance test
Test start date
Test bench drive shaft speed
Friction pair surface maximum temperature
, 2, 3, 50, 100 braking test braking torque
Friction pair surface
Friction lining (pad) wear
Manufacturer
Operation mechanism endurance test
Test end date
Operator
This standard is proposed by the National Technical Committee for Tractor Standardization. This standard is under the jurisdiction of the Luoyang Tractor Research Institute of the Ministry of Machinery Industry. This standard is drafted by Jilin University of Technology. This standard was mainly drafted by Chen Dexing, Wang Dengfeng, 4
Braking time
Republic of China
Machinery industry standard
Tractor brake system test bench
Test method
JB/T7280-94
Published by the Machinery Standardization Research Institute of the Ministry of Machinery Industry and printed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry (P.O. Box 8144, Beijing, 100081, China) )
Copyright reserved
No reproduction allowed
Format 880×12301/16
Word count 16,000
Printing sheet 3/4
First edition in January 1995
First printing in January 1995
Print run 00,001-500
Price 6.00 yuan
No. 94-069
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