Some standard content:
GB17284—1998
Chapter 6 of this standard includes the main technical performance indicators, strength requirements, structural requirements, appearance quality, reliability and other aspects of the whole vehicle. Among them, the main technical performance indicators of the whole vehicle formulate the safety performance, emission, noise and other terms of the whole vehicle; the strength and structure parts mainly adopt the contents of ISO4210:1993 "Bicycles-Safety Requirements" and implement them according to the requirements of its assembly. The contents of other parts are set according to the characteristics of power-assisted bicycles and consumers' requirements for the appearance of power-assisted bicycles. From the date of entry into force, this standard will replace QB1839-93 "Gasoline Power-Assisted Bicycles". Appendix A and Appendix B of this standard are both standard appendices; Appendix C of this standard is a reminder appendix. This standard is proposed by the China Light Industry Federation.
This standard is under the jurisdiction of the National Bicycle Standardization Technical Committee. The drafting units of this standard are: Shanghai Bicycle Research Institute, Traffic Management Research Institute of the Ministry of Public Security, National Bicycle Quality Supervision and Inspection Center, Power-Assisted Bicycle Professional Committee of China Bicycle Association. The main drafter of this standard is Tang Guoping.
1 Scope
National Standard of the People's Republic of China
Gasoline engine boosting bicycle
Gasoline engine boosting bicycleGB 17284 — 1998
This standard specifies the product classification, technical requirements, test methods and inspection rules of gasoline engine boosting bicycles (hereinafter referred to as boosting bicycles). This standard applies to boosting bicycles equipped with gasoline engines. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB3565—93 Bicycle safety requirements
GB/T356693 Bicycle assembly requirements
GB12742—91 Bicycle testing equipment and apparatus technical conditions QB/T121791 Bicycle electroplating technical conditions QB/T1218—91 Bicycle paint technical conditions QB1714—93 Bicycle naming and model compilation method 3 Definitions
This standard adopts the following definitions.
3.1 Gasoline engine power-assisted bicycle
A special bicycle equipped with a gasoline engine, two wheels, and capable of both pedaling and motoring. 3.2 Net weight of the whole vehicle
The weight of the finished vehicle does not include the weight of fuel or a mixture of fuel and lubricating oil. However, it should include the weight of battery fluid, hydraulic oil, coolant, and gasoline engine lubricating oil.
4 Product classification
4.1 Power-assisted bicycles are classified according to the transmission mode between the engine power output shaft and the drive wheel: a) chain drive, code L;
b) friction drive, code M;
c) belt drive, code P;
d) shaft drive, code Z;
e) other drives.
4.2 Model compilation method
4.2.1 The method for compiling power-assisted bicycle models shall be in accordance with the provisions of Chapter 5 of QB1714-93. 4.2.2 The types and wheel diameter codes of power-assisted bicycles are shown in Table 1. Approved by the State Bureau of Technical Supervision on March 25, 1998 110
Implementation on January 1, 1999
Wheel diameter series
Power-assisted bicycle type
Example:
GB 17284-1998
Power-assisted bicycle type and wheel diameter code
Power-assisted bicycle has a wheel diameter of 610mm, a female frame, and a chain drive, and the factory design procedure number is 12, then its model should be: H
Chain drive
Factory design procedure number
Female frame, wheel diameter of 610mm
Special bicycle
5 Main technical parameters and performance
For the main technical parameters and performance indicators of power-assisted bicycles, please refer to Appendix A. Except for the parameters and performance indicators listed in Appendix A that have been specified in this standard, the rest shall be selected by the manufacturer. 6 Technical requirements
6.1 Main technical performance indicators of the whole vehicle
6.1.1 Cylinder working volume
The cylinder working volume of the power-assisted bicycle shall not exceed 30mL. 6.1.2 Net weight of the whole vehicle
The net weight of the power-assisted bicycle shall not exceed 40kg. 6.1.3 Pedal driving ability
The power-assisted bicycle shall be able to be driven by human pedals when the motor clutch is disengaged, and the pedal driving distance in 30 minutes shall not be less than 7km. 6.1.4 Starting performance
The power-assisted bicycle shall be able to start smoothly within the ambient temperature range of 268～303K (-5～30℃), and the starting time shall not exceed 15s. 6.1.5 Rapid pollutants
The idling pollutant emissions of the power-assisted bicycle shall comply with the provisions of Table 2. Table 2 Rapid Idle Pollutant Emissions
Rapid Idle Pollutants
+ Carbon Oxide (CO)
Hydrocarbon (HC)
6.1.6 Maximum Speed
The maximum speed of a power-assisted vehicle shall not exceed 20km/h. 6.1.7 Maximum Speed Riding Noise
Two-stroke Gasoline Engine
Four-stroke Gasoline Engine
Emissions
≤7 000×10-6mg/kg(7 000 ppm)≤1200×10-mg/kg(1200ppm)
GB 17284--1998
When a power-assisted vehicle is running at maximum speed, the noise shall not exceed 72dB(A). 6.1.8 Economic Fuel Consumption
The economic speed fuel consumption of a power-assisted vehicle shall be less than 1.5L/100km. 6.1.9 Braking performance
When the power-assisted bicycle is ridden at the highest speed, its static braking distance should not exceed 4 m. 6.1.10 Minimum no-load stable speed (speed) The minimum no-load stable speed (speed) of the gasoline engine should be less than 2200 r/min. It should be able to rotate stably for 10 minutes at this speed, and its speed fluctuation rate should not exceed ±10%. After running for 10 minutes, the gasoline engine should not stall when the throttle is suddenly opened. 6.2 Strength requirements
6.2.1 Impact of frame/front fork assembly
6.2.1.1 Drop of heavy objects
When tested according to the method specified in 7.2.1.1, there should be no cracks visible to the naked eye on the assembly, and the permanent deformation between the center lines of the front and rear axles of the assembly should not exceed 20 mm.
6.2.1.2 Drop of assembly
According to the provisions of 7.2 of GB3565--93.
6.2.2 Frame/front fork assembly vibration
When tested according to the method specified in 7.2.2, the assembly should not break. 6.2.3 Handlebar static load
Apply a force of 392N at 40mm from the ends of the handlebar cross tube. After 1 minute, the permanent deformation is: fixed handlebar should be less than 2mm; combined handlebar should be less than 3mm.
6.2.4 Torque of handlebar cross tube and stem tube
According to 6.5 of GB3565-93.
6.2.5 Torque of stem tube and front fork stem
According to 6.5 of GB3565-93.
6.2.6 Strength of brake system
According to 5.4.1 of GB3565--93.
6.3 Structural requirements
6.3.1 Foot clearance
6.3.1.1 Ground distance
According to 11.2.1 of GB3565-93.
6.3.1.2 Toe distance
According to 11.2.2 of GB3565-93.
6.3.2 Safety line
6.3.2.1 Safety line of handlebar
According to 6.2 of GB3565-93.
6.3.2.2 Safety line of saddle pipe
According to 12.2 of GB3565-93.
6.3.3 The relative deviation of the clearance between the front and rear rims and the front fork, and the clearance between the flat and upright forks of the frame shall be in accordance with 15.1 of GB/T3566-93. 6.3.4 Relative deviation of the center plane of the front and rear wheels
According to 15.2 of GB/T3566-93.
6.3.5 Valve hole position
According to 12.1 of GB/T3566-93.
6.3.6 Sharp edges and protrusions
According to 4.1 and 4.2 of GB3565-93. GB 17284-1998
6.3.7 No oil leakage is allowed at the joints of the sealing surfaces of the gasoline engine. 6.3.8 The clutch should not slip when engaged and should be completely disengaged after separation. 6.3.9 Wiring device
According to 15.1 of GB3565-93.2 regulations.
6.3.10 The power-assisted bicycle shall be equipped with a headlight or front reflector; a rear reflector and a side reflector; and a horn device shall also be installed. 6.4 Appearance quality of the whole vehicle
6.4.1 The surface of each exposed part and component of the power-assisted bicycle shall be clean, free of stains and rust; trademarks and decals shall be complete, clear and correctly positioned. 6.4.2 All electroplated parts shall comply with the provisions of 5.1.1 chrome-plated Class I parts and galvanized Class I parts of QB/T1217-91. 6.4.3 All painted parts shall comply with the provisions of 3.1 Class I parts of QB/T1218-91. 6.4.4 The surface of each plastic part shall be uniform in color, without obvious flash, scratches, cracks and dents. 6.5 Reliability
6.5.1 The reliability mileage of the power-assisted bicycle shall be no less than 1500km. 6.5.2 The comprehensive reliability evaluation index value Q shall not be less than 70, and the calculation formula is as follows: Q == 0.008695(T, +T,) + 80e-0.124 D Where: Q
Reliability evaluation score of the test sample;
Average first failure mileage, km,
When ↑,>800 km, let T:=800 km; T,—average failure interval mileage, km,
When ↑,>1500km, let ↑=1500km; D
Equivalent failure rate of the test sample.
Among them:
a) Average first failure mileage,
Where: T: ~—Average first failure mileage of the test sample, km (not counting 4 types of failures); n
Number of sub-samples,
n'——Number of sub-samples with failures (not counting 4 types of failures); when n0, count as n=1;
t: First failure mileage of the ith sub-sample, km; t—Test end mileage, km.
b) Average failure interval mileage,
Where: 7. ——Average failure interval mileage of the test sample, km; Total number of failures of the test sample (not counting 4 types of failures); when r=0, count as r=1;
Test end mileage, km.
c) Equivalent failure rate D
· (3))
Equivalent failure rate of the test sample vehicle;
Wherein, D—
GB 17284--1998
D = 1 000 X
Equivalent failure coefficient of the first type of failure, its value is: E
Fatal failure E=100,
General failure ε3=2,
Serious failure E2-20,
Minor failure E.0.2;
—The first type of failure occurred in the test sample vehicle. 7 Test methods
The testing equipment and instruments used in this chapter shall comply with the relevant provisions of GB12742--91. 7.1 Main technical performance tests of the whole vehicle
7.1.1 Cylinder working volume test
Use a vernier caliper to measure the cylinder bore and working stroke of the gasoline engine, and calculate the cylinder working volume according to formula (5): D2
Where: V——- cylinder working volume, mL; D-- cylinder bore, cm;
S--- working stroke, cm.
The calculated value is accurate to 0.1, and the result should comply with the provisions of 6.1.1. 7.1.2 Vehicle net weight test
Use a scale, and the weight measured should comply with the provisions of 6.1.2. 7.1.3 Pedaling ability test
7.1.3.1 Test conditions
a) The weight of the rider should be 70-85kg. If the rider weighs less than 70kg, he should be weighted to 70kg. b) Test road surface: flat asphalt or concrete road surface. c) Wind speed: ≤3 m/s.
7.1.3.2 Test method
A test section is set up on the test road. The round trip ride is 7 km in total. The time taken shall comply with the provisions of 6.1.3. 7.1.4 Starting performance test
(4)
(5)
The test is timed with a stopwatch. When the power-assisted vehicle is in a cold state, the interval from receiving the signal to start the gasoline engine to the gasoline engine being able to work continuously is the starting time, and it shall comply with the provisions of 6.1.4. 7.1.5 Rapid pollutant test
This test measures the concentration of carbon monoxide and hydrocarbons emitted by the power-assisted vehicle under idling conditions. 7.1.5.1 Test conditions
a) Rapid operating conditions: The gasoline engine is at the lowest stable speed without load, and the choke is fully open. b) The concentration of carbon monoxide in the exhaust gas is expressed as a volume percentage (%), and the concentration of hydrocarbons is expressed as parts per million by volume. c) Test instrument
1) A non-spectral infrared carbon monoxide and hydrocarbon gas analyzer should be used, and the instrument should be suitable for two-stroke and four-stroke gasoline engines. 2) The length of the sampling probe should be not less than 600mm, and the length of the sampling hose should be not less than 3m. The probe hose is not allowed to have pollutants and condensate. 3) The sampling system of the instrument must not leak. 7.1.5.2 Test method
a) The gasoline engine is accelerated from idle to medium speed, maintained for 5s, and then reduced to idle state. The speed is adjusted according to the instructions of the test vehicle. 114
GB 17284 ---1998
b) The gasoline engine is operated for 3~5min to reach the specified hot state. c) Insert the sampling probe into the exhaust muffler to a depth of 300mm. If the insertion depth is insufficient, add a pipe to make it up to 300mm in length and ensure that there is no leakage at the interface.
d) Read the indicated values of carbon monoxide and hydrocarbons 30s after the probe is inserted, which is the measured value. e) Rounding of numbers: round carbon monoxide to one decimal place, and round hydrocarbons to hundreds. f) Test carbon monoxide and hydrocarbons three times each and take the arithmetic mean. The value should comply with the provisions of Table 2. 7.1.6 Maximum speed test
7.1.6.1 Test conditions
a) The slope of the test track should not exceed 1%. The road surface should be hard, paved with concrete or pure asphalt, and there should be no soft dust or gravel. b) The test environment temperature is 268~303K (-5~30℃), and the wind speed is not more than 3m/s. The test should not be carried out in rainy or snowy weather. c) The brand of gasoline and lubricating oil used in the power-assisted bicycle shall comply with the provisions of the product manual. The tires shall be fully inflated according to the recommended inflation pressure. Before the test, the power-assisted bicycle shall be checked and adjusted if necessary. No further adjustments shall be made during the test. d) The weight of the rider shall be 70-85 kg. If the rider weighs less than 70 kg, add a counterweight to 70 kg. 7.1.6.2 Test method
a) A 100m test section shall be set on the test track, with a sufficiently long auxiliary riding area at both ends. b) Before riding to the test section, the power-assisted bicycle shall complete the entire acceleration process, reach the maximum speed, and pass the test section at this speed.
c) Determine the time it takes for the power-assisted bicycle to go back and forth through the test section. d) Calculate the maximum speed according to formula (6):
Where: u——maximum speed, km/h;
t——time it takes to go back and forth through the test section, s. e) The test shall be carried out twice in a row, and the arithmetic mean shall be taken. The result shall comply with the provisions of 6.1.6. 7.1.7 Maximum speed riding noise test
7.1.7.1 Test conditions
The test conditions for the maximum speed riding noise of the power-assisted bicycle are the same as those specified in 7.1.6.1. In addition, the following items shall be met: (6)
a) The test site shall be flat and open. There shall be no large reflectors, such as tall buildings, walls, rocks or bridges, within a radius of about 50m from the test center.
b) The background noise (including wind noise) of the test area shall be at least 10dB (A) lower than the noise of the power-assisted bicycle under test, and there shall be no interference from other accidental sources.
c) Except for the tester, no other person shall be present near the sound level meter. If indispensable, they must stand behind the tester. 7.1.7.2 Test method
a) The layout of the test area is shown in Figure 1.
b) The sound level meter is measured with the "A" weighting network and the "fast" gear, and the minimum reading unit is α.5dB. The sound level meter is placed at a height of 1.2m from the ground.
c) The power-assisted vehicle should keep the throttle stable and ride at the highest speed through the test area at a constant speed, and read the maximum reading of the sound level meter. Take the average value of the sound level meters on the left and right sides.
d) The power-assisted vehicle is ridden back and forth through the test area once in the same way, and the larger of the two average values is taken as the maximum riding noise of the power-assisted vehicle. Its value should comply with the provisions of 6.1.7.
Test area
7.1.8 Economic fuel consumption test
7.1.8.1 Test conditions
Sound level meter
GB17284-1998
The test conditions for economic fuel consumption of power-assisted vehicles are the same as those specified in 7.1.6.1. 7.5mbzxz.net
Sound level meter
7.1.8.2 Take the upper, middle and lower values of the economic speed range provided by the manufacturer, ride three times for a total of 10 km, and measure the fuel consumption of the power-assisted bicycle. The lowest value is the economic fuel consumption. The fuel consumption can be measured by the difference between the fuel injected into the fuel tank in advance and the fuel actually discharged from the fuel tank after the test, which is the fuel consumption for 10 km.
The economic fuel consumption of the power-assisted bicycle is calculated according to formula (7): Gp
Where: G. -- Economic fuel consumption, L/100 km; G, fuel consumption for a total of 10 km round trip, mL; — Volumetric mixing ratio of gasoline and lubricating oil.
The calculated G. value should comply with the provisions of 6.1.8. 7.1.9 Braking performance test
The braking performance of the power-assisted bicycle shall comply with the provisions of Chapter 22 of GB356593. 7.1.10 Minimum no-load stable speed (idle) test (7)
During the test, the gasoline engine is not connected to the dynamometer, the throttle is placed in the rapid position, the no-load stable speed of the gasoline engine is adjusted to the lowest, and it can run stably at this speed for 10 minutes. The speed and its fluctuation are measured. The measured values should comply with the provisions of 6.1.10. Then the throttle is suddenly opened, and the gasoline engine should not stall.
This test should be carried out on the whole vehicle.
7.2 Strength test
7.2.1 Frame/front fork assembly test
7.2.1.1 Heavy object drop test
According to the provisions of 25.1 of GB3565-93.
7.2.1.2 Assembly drop test
GB 17284—1998
According to 25.2 of GB3565—93, but a weight of 85kg should be fastened to the seat tube. 7.2.2 Frame/front fork assembly vibration test a) The frame/front fork assembly vibration test of the power-assisted bicycle should be carried out on a special vibration test machine. b) See Table 3 for test conditions.
3 Vibration test conditions
Load, N
Front tube
Saddle
Midshaft
Vibration frequency
6.6~～10
Acceleration of vibration-adding part
m/s2(G)
In addition to the loads in the table, add a load of 98N to the gasoline engine installation part. The load of the rear axle transmission is applied to the middle axis. The relationship between the acceleration of the vibration part and the vibration frequency and amplitude is as follows (8): g 0.04 α·n2
Wherein: g-
acceleration, G;
half amplitude, cm;
vibration frequency, Hz.
c) Test method
Install the frame/front fork assembly on the vibration test machine as shown in Figure 2, and then perform a vertical up and down vibration test on the frame/front fork assembly according to the test conditions listed in Table 3. P
Amplitude 2n
Half amplitude n
Vibration table
When the frame/front fork assembly is installed, the front and rear axles should be located at the same horizontal position. The load of the front tube should be installed on the upper end of the front fork lock nut using a clamp and a code holder. P2
The frame specimen shall be provided with a seat tube, and the minimum insertion depth mark of the seat tube shall be embedded in the seat tube. The load of the saddle shall be equally suspended on the left and right sides through a saddle-shaped load seat. The load seat shall be fastened to the top of the seat tube with a clamp, and the clamping length shall not be less than 20 mm. The center of gravity of the load shall pass through the center of the top of the frame seat tube.
The load of the middle axis shall be fastened to the left and right sides of the middle axis with a circular code. The vibration frequency may be selected arbitrarily between 6.6 and 10 Hz, but the resonance frequency of the frame/front fork assembly shall be avoided. d) Regardless of the form of the frame used for the power-assisted bicycle, it shall pass the vibration test for 100,000 times. 7.2.3 Static load test of handlebar
GB 17284 --1998
Safety mark
As shown in Figure 3, the handlebar seat tube shall be inserted to the safety mark and fixed. First, apply the specified force at 40mm from one end of the handlebar tube. After 1 minute, remove the force and measure the permanent deformation with a dial indicator. Then repeat the test at the other end. The maximum value of the two values shall prevail. The measurement position is 30mm from the end of the handlebar tube.
When testing the combined handlebar, the force application part of the handlebar tube should be in a horizontal position. 7.2.4 The torque test of the handlebar tube and the stem tube shall comply with 24.2 of GB3565--93.
7.2.5 The torque test of the stem tube and the front fork stem shall comply with 24.3 of GB3565-93.
7.2.6 The strength test of the brake system
shall comply with 21.1 of GB3565-93.
7.3 Structural requirements test
7.3.1 Foot gap test
7.3.1.1 Ground distance
According to 11.2.1 of GB3565-93.
7.3.1.2 Toe clearance
According to 11.2.2 of GB 3565-93. 7.3.2 Safety line test
Visual inspection and measurement with a ruler.
7.3.3 Relative deviation test of the clearance between the front and rear rims and the front fork, the horizontal and vertical forks of the frame shall be in accordance with Chapter 26 of GB/T3566--93.
7.3.4 Relative deviation test of the center plane of the front and rear wheels shall be in accordance with Chapter 27 of GB/T3566-93.
7.3.5 Valve hole position test
Visual inspection.
7.3.6 Sharp edge and protrusion test
Sharp edges shall be checked by hand and visual inspection.
Protrusions shall be checked by a card plate, a vernier caliper and an exposed protrusion test cylindrical rod as shown in Figure 4. 118
7.3.7 Gasoline engine sealing performance test
GB 17284 -- 1998
Unit: mm
When the power-assisted vehicle is in hot working condition, the oil pipe joints, joint surfaces, threaded connections, exposed ends of rotating shafts, etc., the static joint surfaces shall be free of oil marks by hand touch, and the dynamic joint surfaces shall be free of oil drops and oil flow marks.
7.3.8 Clutch performance test
While the power-assisted vehicle is driving, check whether the clutch has any slipping phenomenon in the engaged state and whether it is completely disengaged after separation. 7.3.9 Electric wire device test
Visually check whether the electrical circuit device touches the moving parts or sharp edges. Use a dynamometer to check the connection firmness of the circuit. 7.3.10 Inspection of the installation of lights, reflectors and horn devices Check whether the power-assisted vehicle is equipped with the specified headlights or front reflectors, rear reflectors and side reflectors. The headlights should be able to light up when the gasoline engine is in operation. Check whether the power-assisted vehicle is equipped with the specified horn device. 7.4 Vehicle appearance quality test
Inspect by hand and visual inspection.
7.5 Reliability test
7.5.1 Inspection and adjustment before the test
7.5.1.1 According to the relevant technical documents provided by the manufacturer, check and adjust the following items: spark plug gap, ignition advance angle, relay contact gap, engine speed, brake handle, clutch handle, free travel and working travel of throttle control cable, handlebar rotation angle and steering flexibility, wheel tightness, tire pressure, wheel hub and brake pad gap and transmission chain, transmission belt tightness, etc., so that all components are kept in good working condition. 7.5.1.2 During the adjustment process, a check driving of no more than 10 km is allowed to ensure that the adjustment is reasonable. 7.5.2 Test conditions
7.5.2.1 Test road
a) Flat asphalt road and concrete road.
b) The driving mileage shall include no less than 15% of the total mileage of gravel road and dirt road. c) The driving mileage on various slopes and bridges shall not be less than 20 km. 7.5.2.2 The driving mileage at night shall not be less than 50 km. 7.5.2.3 Climate
All weather, but the driving mileage on rainy and snowy days shall not exceed 30% of the total driving distance. 119
7.5.2.4 Rider
GB 17284—1998
a) The total weight of the rider and equipment shall be 70-85 kg. If the weight is less than 70 kg, a counterweight shall be added to 70 kg. b) When riding, the rider should sit on the seat, hold the handlebars with both hands, step on the footrests with both feet, and stretch his arms normally. 7.5.3 Test
7.5.3.1 Running-in test
The first 500km is the running-in test of the power-assisted bicycle.
a) The running speed during the running-in period shall be the speed recommended by the manufacturer's manual. b) During the running-in period, the tightness and working condition of each part of the vehicle should be checked frequently. It is allowed to make adjustments and maintenance in a short time with simple tools according to the maintenance manual provided by the manufacturer.
c) In the last 20km of the running-in, the vehicle should be observed to see if it can be tested for performance. d) The running-in process should be recorded in detail according to Appendix C. 7.5.3.2 Non-running-in test
The last 1000km is a non-running-in test.
a) While ensuring driving safety, drive at a higher speed as possible, and the minimum speed should not be less than 15km/h. Sliding is not allowed during the entire test.
b) Check the vehicle at any time during the test. It is allowed to check and adjust the vehicle according to the provisions of Table 4, but all kinds of troubleshooting and replacement of parts should be included in the fault statistics.
Table 4 Maintenance regulations for stages
Brake system
Drive chain (belt)
Spark plug
Tire pressure
Air filter element
Engine oil, gasoline filter element, filter
Crankcase transmission lubricating oil
Cylinder head, piston
Carburetor
Each lubricating part
External tight fittings
Maintenance content
Inspection and adjustment is allowed
Inspection and adjustment is allowed||t t||Inspect, and allow to remove carbon deposits, adjust
Inspect, inflate if necessary
Inspect, clean if necessary
Inspect, clean if necessary
Replace, add
Remove carbon deposits
Inspect, clean if necessary
Add lubricating oil
Inspect, tighten if necessary
Note: ○—Inspect, adjust, clean, inflate, etc.; △7.5.3.3 Fault classification
Replace; ×-
—Add; V-
Inspect.
According to the nature and degree of harm of the fault, the fault is divided into four categories. The classification principle is shown in Table 5. 120
Specified mileage, km
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