JB/T 50096-1997 Reliability assessment method for three-wheeled agricultural transport vehicles
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T50096—1997
Three-wheeled agricultural transport vehicle
Reliability assessment and evaluation method
(Internal use)
Published on August 12, 1997
Ministry of Machinery Industry of the People's Republic of China
Implementation on January 1, 1998
JB/T500961997
This standard is formulated on the basis of JB/T7237-94 "Three-wheeled agricultural transport vehicle test method". The performance test method in the reliability assessment test is consistent with the provisions of JB/T7237, and the reliability assessment index is equivalent to the reliability index of qualified products in JB/T500951997 "Three-wheeled agricultural transport vehicle product quality classification". Appendix A of this standard is the appendix of the standard.
This standard is proposed by the National Technical Committee for Agricultural Machinery Standardization. This standard is under the jurisdiction of the National Agricultural Machinery Standardization Technical Committee. The drafting unit of this standard is the Chinese Academy of Agricultural Mechanization Sciences. The main drafters of this standard are Ouyang Dong and Zhang Weisheng. 1
1 Scope
Machinery Industry Standard of the People's Republic of China
Three-wheeled Agricultural Transport Vehicle
Reliability Assessment and Evaluation Method
(Internal Use)
JB/T 50096-1997
This standard specifies the requirements for the reliability assessment and evaluation of three-wheeled agricultural transport vehicles, the assessment test methods, the fault classification and judgment rules, and the calculation of the assessment index.
This standard is applicable to the reliability assessment and evaluation of mass-produced three-wheeled agricultural transport vehicles (hereinafter referred to as three-wheeled vehicles). The reliability assessment test can be referred to when conducting type tests on new products. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were all valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB 1496--79
CB 3187- 82
JB/T 7237 -- 94
JB/T 50095-·1997
3 Assessment requirements
3.1 Assessment mileage
Methods for measuring noise of motor vehicles
Basic terms and definitions of reliability
Test methods for three-wheeled agricultural transport vehicles
Quality classification of three-wheeled agricultural transport vehicles
3.1.1 When the maximum speed of a three-wheeled vehicle is less than or equal to 30 km/h, the assessment mileage is 7500 km. 3.1.2 When the maximum speed of a three-wheeled vehicle is greater than 30 km/h but less than or equal to 40 km/h, the assessment mileage is 10000 km. 3.1.3 When adopting the enhanced test, the test mileage can be appropriately reduced according to the enhanced coefficient while ensuring that the failure mechanism remains unchanged. 3.2 Driving Roads
3.2.1 The test should be carried out on various roads. The driving mileage on flat roads (referring to roads with a road surface flatness of Class C or below and a maximum slope of less than 5%) shall not exceed 50% of the test mileage, the driving mileage on mountain roads (referring to roads with an average slope of not less than 4%, a maximum slope of not less than 8%, a continuous slope of more than 3km, and a road surface flatness of Class C or below) shall not be less than 20% of the test mileage, and the driving mileage on bad roads (referring to roads with a solid roadbed, uneven road surface, and a road surface flatness of Class E or below. When the test sample vehicle drives on such a road surface, it should be subjected to strong vibration and twisting loads, but should not have too much impact) shall not be less than 30% of the test mileage. When conducting reliability test at the test site, the driving mileage distribution of various roads should refer to the above provisions. 3.2.2 Various roads should constitute a cycle within a certain mileage as much as possible according to the prescribed proportion. If there are difficulties, the driving can also be concentrated in the following proportions: 25% on flat roads, 20% on mountain roads, 30% on bad roads, and 25% on flat roads. 3.3 Driving Operation
On the premise of ensuring safety, the vehicle should be driven at a higher speed as much as possible. The average speed during the entire test period should not be less than 60% of the highest measured speed. The night mileage of each test sample vehicle should not be less than 5% of the test mileage, and the average speed on bad roads should not be less than 40% of the highest measured speed. For every 100km of driving, there should be at least two stops and starts, one reverse driving of 100m and two brakings; when driving on mountain roads, there should be at least one uphill stop and start every 100km. Approved by the Ministry of Machinery Industry on August 12, 1997
Implementation on January 1, 1998
3.4 Evaluation indicators
JB/T 50096--1997
3.4.1 The reliability index values for evaluating tricycle products shall comply with the provisions of JB/T50095. 3.4.2 During the assessment process, if any vehicle has a fatal fault (Class I), the product shall be judged as having failed the reliability assessment. 3.4.3 During the running-in and performance tests, if a serious fault (Class I) or a fatal fault (Class I) occurs, the product shall be judged as having failed the reliability assessment. 4.1 Sampling
4.1.1 The test sample vehicles shall be randomly selected by the sampling personnel of the test responsible unit from the finished products that are normally produced by the production enterprise and have passed the inspection and entered the warehouse. There are 2 test sample vehicles, and 1~2 more vehicles can be selected and sealed for standby. The sampling base shall not be less than 20 vehicles. 4.1.2 During the surprise inspection, the sampling location and sampling base are not limited. 4.1.3 The selected test sample vehicles shall be shipped to the test site by the production enterprise on the specified date. 4.1.4 When the sample vehicle is damaged during transportation or due to an accidental human accident, the spare vehicle is allowed to be used with the consent of the test responsible unit.
4.2 Acceptance
4.2.1 According to the items specified in Table A1 of Appendix A of JB/T7237-94, the sample vehicles shall be accepted at the test site, and the problems found shall be recorded in detail in the table.
4.2.2 If the prototype needs to be repaired or adjusted, it shall be carried out only after the approval of the responsible unit for the test. 4.3 Running-in
The qualified prototype shall be run-in according to Table 1. 4.3.1
Table 1 Running-in Specifications
Mileage
≥35～235
>235350
Load Condition
60% of rated load
50% of rated maximum speed
75% of rated maximum speed
Rated maximum speed
Note: 1, 2, 3 and reverse gears shall be operated at 10%, 28%, 60% and 2% of the specified mileage respectively. When there are more than four gears, select four gears that are closer to the speed of ordinary tricycles for running-in.
4.3.3 The running-in mileage shall be recorded in Table A1 of Appendix A of JB/T723794. 4.4 Performance test
4.4.1 Before and after the driving test, the following items shall be tested under the same conditions: maximum vehicle speed;
minimum stable vehicle speed at the highest gear;
-acceleration performance at the highest gear;
service braking performance;
parking braking performance;
-road driving fuel consumption rate;
-exterior noise of the vehicle during acceleration.
4.4.2 The performance test conditions and test methods shall be carried out in accordance with the relevant provisions of JB/T7237, and the exterior noise of the vehicle during acceleration shall be carried out in accordance with the provisions of GB1496.
4.4.3 The performance test results before and after the driving test shall be recorded in Table A15 of Appendix A of JB/T7237-94. 4.5 Driving test
4.5.1 The test vehicle shall be driven by a driver recognized by the responsible unit (including the driver of the manufacturer). 2
JB/T 50096—1997
4.5.2 The test vehicle shall be driven with full load (loaded according to the rated load), and a 65kg weight may be used to replace the position where the passenger is required. 4.5.3 The test shall be carried out at the selected test site. The test mileage shall be in accordance with 3.1, the test road driving ratio shall be in accordance with 3.2, and the driving operation shall be in accordance with 3.3.
4.5.4 Each test vehicle shall be recorded by a dedicated person, and each shift shall fill in the shift record sheet in accordance with the requirements of Table A12 in Appendix A of JB/T723794. Record the mileage, road conditions, driving time, fuel consumption and fault conditions, etc. 4.5.5 During the test, normal maintenance and adjustment shall be carried out according to the product manual, and the technical status of the test vehicle shall not be adjusted or changed arbitrarily.
4.5.6 During the entire test process (including running-in and performance tests), all abnormal phenomena occurring on the test vehicle shall be recorded in detail in Table 12 of Appendix A of JB/T7237-94.
4.5.7 During the test, if one of the two vehicles has a fatal fault, the test can be terminated. In the event of general or serious faults, the test can be continued after the fault is eliminated.
4.6 Final inspection
After the test, the test sample vehicle shall be comprehensively inspected and all newly discovered faults shall be recorded. 5 Fault classification and judgment rules
5.1 Fault classification
5.1.1 Faults are divided into essential faults, subordinate faults and misuse faults. The definition is shown in GB31875.1.2. According to the degree of harm caused by the tricycle fault and the difficulty of troubleshooting, the fault is divided into four categories: fatal faults, serious faults, general faults and minor faults (see Table 2). Table 2 Fault classification
5.2 Fault judgment rules
Fatal faults
Serious faults
General faults
Minor faults
Classification principles
Endanger the driving safety of the tricycle, cause personal injury or death or cause the main assembly to be scrapped, and cause! Faults that cause major economic losses
Affect the driving safety of the tricycle, or cause damage to the main parts or the specified important performance indicators are obviously beyond the specified range. Faults that cannot be eliminated with wearing parts and on-board tools in a short time (about 30 minutes) and must be stopped for repair. Faults that obviously affect normal use or performance indicators exceed the specified range. Generally, there is no damage to the main parts, and the faults can be eliminated with wearing parts and on-board tools in a short time (about 30 minutes). Or the appearance decorative protective layer is severely peeled off, which does not cause the tricycle to stop running or the performance indicators exceed the limit, and does not need to be replaced. Faults that can be easily eliminated with on-board tools in about 5 minutes, or the appearance decorative protective layer is slightly peeled off. 5.2.1 When calculating the reliability index, only the number and category of essential faults are counted. If a subordinate fault is caused by an essential fault, the fault category should be determined according to the fault that causes the most serious consequences, and only one fault is counted. Misuse faults and subordinate faults caused by them are not counted in the number of faults, but they should be recorded truthfully and in detail.
5.2.2 When a component that has been adjusted and maintained according to the instruction manual and has reached the specified life limit fails, no fault treatment will be performed, but a detailed record shall be made.
5.2.3 When counting the number of failures such as "three leaks" and loose fasteners, each joint surface shall be counted as one failure. 5.2.4 After the failure is eliminated, the repeated occurrence of the same failure shall be accumulated according to the actual number of failures. However, if the failure recurs due to improper treatment and repair, it shall be counted as one failure.
JB/T 50096--1997
5.2.5 When judging the fault category, the final consequences should be used for judgment, and it can only be judged as one of the four types of faults. 5.2.6 When judging the fault category, you can refer to Appendix A (the standard appendix), but due to the differences in the structures of various vehicle models, the consequences and difficulty of eliminating the same fault mode are quite different, so it cannot be copied completely. Instead, you should refer to the fault examples in Appendix A based on the fault definition and judgment rules, and judge the fault category of each fault based on the actual situation. 6 Calculation of evaluation indicators| |tt||For the reliability assessment test of tricycles, it is recommended to adopt the on-site reliability driving test, with fixed-range truncation. The following indicators for evaluating the reliability of tricycles can be selected according to different test purposes and requirements. At present, the recommended indicators for evaluating the reliability of mass-produced tricycles are the mean mileage between failures (point estimate) and the comprehensive score of no failure. 6.1 Mean mileage to first failure
a) Point estimate:
b) Lower limit of one-sided confidence interval:
(MTTFF)
Where MTTFF-
Zs, + (n - r.)S.
2[2s, + (nr)s,]
X(α,2r, + 2)
Mean mileage to first failure (point estimate), km; (MTTFF).~Mean mileage to first failure (lower limit of one-sided confidence interval), km; -Number of test vehicles;
S. Specified cut-off mileage for fixed-range truncation test, km; r. -Number of test vehicles with first failure (excluding minor failures) during the test period; s. -Sum of mileage of test vehicles with first failure (excluding minor failures). km; X2(α.2r, +2) - -Significance level is α, self The X2 quantile with degree (2r+2). This standard stipulates that α=0.35, and the X2 value at this time is shown in Table 3. ·(1)
If all test vehicles have no faults (except minor faults) after reaching the specified test mileage, it is stipulated that: MTTFFnSe. Table 3 X2 values when α=0.35
X\(a,2r,+2).X(a,2r+2)
X*(a.2r.+2).X(α,2r+2)
X'(a.2r, +2).,X'(α,2r+2)
6.2 Mean mileage between failures
a) Point estimate:
b) Lower limit of one-sided confidence interval:
In: MTBF--
MTBF =
2nsS.
X2(α,2r + 2)
Mean mileage between failures (point estimate).km; 4
JB/T 50096—1997
Mean mileage between failures (lower limit of one-sided confidence interval), km; Number of test vehicles:
The specified cut-off mileage for fixed-range truncation test, km; The total number of failures (excluding minor failures) that occurred on n test vehicles during the test: X2(α.2r+2)-
--X2 quantile with a significance level of α and degrees of freedom of (2r+2). This standard stipulates that α is taken as 0.35, and the X2 value is shown in Table 3. If all test vehicles have no faults (except for minor faults) after reaching the specified test mileage, it is stipulated that: MTBF>nS. 6.3 Comprehensive score for no faults
Comprehensive score for no faults, points;
Where: Q——
Number of test vehicles;
Q= 100 -
S.(K: ·E.)
-The specified cut-off mileage for the fixed-distance truncation test, km; The MTBF index value of the superior product specified in SJB/T50095, km;. The total number of various types of faults that occurred during the test; (5)
K,——-The criticality coefficient of the ith fault, which is specified as K=40 for severe faults, K=10 for general faults, and K2 for minor faults; E.
The mileage coefficient when the ith fault occurs, calculated according to formula (6): E.
Where: S.--The cumulative mileage of the test vehicle when the ith fault occurs, km. When the calculation result shows that Q<0, it is specified to be scored as 0. 6.4 Average repair time
Where: MTTR
Average repair time.h;
Test time.\Total number of fault repairs of a test sample; The sum of the repair time of r faults of a test sample, h. 6.5
Average warranty cost rate
× 100%
Wu Zhong: PWC
Average warranty cost rate, %;
c-——The sum of the repair costs of n test sample vehicles during the test period, RMB; C
7Test report
The factory retail price of a test sample, RMB.
7.1 Statistical calculation of test results
7.1.1 All essential faults (including performance exceeding limits) occurring during the test (including during the running-in and performance test) shall be summarized in the order of occurrence in Table A14 of Appendix A of JB/T7237-94. When counting the cumulative mileage when the fault occurs: the fault occurring before the driving test shall be counted as zero kilometers; the cumulative mileage of the fault occurring during the performance retest and final inspection after the driving test shall be counted as the test end mileage (i.e. the assessment mileage).
7.1.2 According to the relevant provisions of Chapter 5, the number of various types of faults shall be counted, and the reliability index value of the test sample vehicle shall be calculated according to the calculation formula in Chapter 6. And recorded in Table 4.
Fatal failure number
Serious failure number
General failure number
Minor failure number
Test report writing
Writing requirements
JB/T 50096—1997
Reliability index and summary of various failure numbers
(MTTFF)L
(MTBF)L
The report cover, first page and last page shall comply with the provisions of Appendix A Figure A1 in JB/T7237—94. 7.2. 1.1
7.2.1.2 The report body lists the following contents in order: Table of Contents;
Preface;
Main technical specifications of the test sample vehicle, including:
a) Complete vehicle: brand, model, external dimensions, wheelbase, track width, minimum ground clearance, internal dimensions of the cargo box, rated load capacity; b) Engine: brand, model, manufacturer, rated power, rated speed, cooling method, starting method; c) Clutch: type, number of plates, diameter; d) Transmission: number of gears, speed of each gear;
e) Rear axle and brake assembly: rear axle type, brake type, brake drum diameter; f) Suspension and front shock absorber: suspension type, number and specifications of leaf springs, shock absorber type and specifications; g) Tires: front and rear tire specifications.
Test conditions and test situations: road conditions, test instruments and accuracy, test process, fault conditions, etc.; Test results: summary of test results, test conclusions, result analysis and related suggestions, etc. 6
Engine
Engine
Drive chain or belt
Gearbox
Brake operating device
Transfer assembly
Frame, wheel
Front shock absorber
Engine
Engine
Engine
Engine
Engine
Engine crankshaft main bearing cover bolt
Engine fastening bolt
Clutch
Pressure plate spring
Drive belt or chain
Gearbox
Gearbox
Gearbox
Leaf spring assembly
JB/T 50096-1997
Appendix A
(Appendix to the standard)
Examples of failures of three-wheeled agricultural transport vehicles
Table A1 Examples of fatal failures
Failure mode
Broken, untied
Broken, damaged
Broken, failed
Functional failure
Broken, fallen off
Broken, damaged
Situation description
Occurs during normal turning
Failure of the oil cut-off mechanism and loss of speed control cause the engine to be scrapped. Piston or connecting rod bolts break, resulting in damage to the cylinder body, causing the engine to be scrapped. Occurs during driving, causing major accidents
Shaft breakage or gear damage, resulting in the scrapping of the gearbox
Axle housing breakage, speed differential gear damage, causing The assembly is scrapped, resulting in brake failure, causing a major accident
Occurs during driving, and steering loss of control causes a major accident. Occurs during driving
Breakage during driving·Steering loss of control causes serious consequences. Occurs during driving and causes a major accident
Table A2 Examples of serious faults
Failure mode
Oil and gas leakage
Function failure
Breakage, falling off
Shifting out of gear, random gear
Breakage, damage
Breakage, damage
Situation description
Caused by the breakage of the speed regulating high-speed spring, but did not cause the engine assembly to be scrapped. Crankshaft locking
Piston stuck in the cylinder
Foreign objects entering and pulling
Obvious knocking
Serious black smoke||t t||No serious consequences
Multiple connecting bolts are broken, but the connection has not completely failed. Continuous burning for more than two times
The machine parts are burned and cannot be cut off or cannot transmit torque. Multiple breaks, poor separation and combination
Multiple belts are broken or chains fall off, and no major accidents can be ruled out
Multiple occurrences
Gears, shafts or bearings are broken or broken, but the assembly is not scrapped. Gears, shafts, etc. are broken but the assembly is not scrapped. The first piece or two or more pieces are broken
Brake system
Rear tire
Load-bearing parts such as half-axle housings and wheels
Power transmission parts such as steering and brake systems
Front steering and rear axle and frame connection
Frame and car body connection device
Cab and car Frame connection device
Tire, leaf spring fastening bolts
Frame longitudinal and transverse beams
Generator, battery
Maximum speed
Service brake
Parking brake
Brake deviation
Starting performance
Fuel tank
Engine
Engine
Engine
Drive belt and chain
Engine fastening bolts
Clutch
Clutch friction plate
Adjusting screw
Separation lever
Gearbox
Gearbox
Gearbox (joined rear axle)
Gearbox (joined rear axle)
JB/T 50096--1997
Table A2 (end)
Failure mode
Function failure
Crack or damage
Crack or damage
Crack or break
Function failure
Crack and oil leakage
Situation description
Brake drum rupture or brake rod break, no major accident Excessive wear of bearing or damage to the keyway working surface of the half-axle wheel hub Occurs during driving, no major accident
Serious weld needs to be replaced
Not completely lost function
Not lost function
Not failed
Not caused connection failure
Not caused connection failure
|No connection failure
Cracks or breaks seriously affect the strength of the frame
Need to be replaced
Over 40km/h
Braking distance is greater than 4.5m (no load) or greater than 5.0m (full load)Slope <20%
Deviation ≥8cm
Cannot start, need to replace parts
Need to replace parts
General fault examples
Fault mode
Unstable speed regulation
Unstable rest speed
Abnormal noise or knocking
Breakage or looseness
Abnormal wear
Abnormal wear
Slippage, random gears
Difficult to shift gears
Loose nut of speed control rack
Speed control rack Issue
The reason is unknown, no damage
A belt is broken or the chain is loose, no serious accident is caused. A bolt is broken
The pull rod adjustment bolt falls off
Severe wear and tear, need to be replaced
Need to be replaced
Need to be replaced
Adjustment can eliminate
The loose connection of the joystick causes the gear to be disordered. Adjustment can eliminate it. Occasionally, it is easy to eliminate
Non-parts damage
Front shock absorber
Front shock absorber
Steering device
Muffler
Speed control mechanism
Leaf spring assembly
Wheel and tire
Leaf spring tire bolt
Lighting equipment (headlight, rear position light,| |tt||License plate light, brake light, turn signal light)
Headlight
Paint film or electroplating layer
Pressure relief mechanism
Starting performance
Most stable speed at highest gear
Use fuel consumption rate
External acceleration noise
Maximum acceleration performance
Joint surfaces of various parts
Engine
Clutch
Clutch
Speed shifting mechanism
Cab
Cab bracket
Joint surfaces of various parts
General fasteners
Front guard plate and tire fender
Oil circuit or circuit
Paint film or electroplating layer
JB/T 50096—1997
Table A3 (end)
Failure mode
Function reduction
Damage, falling off
Dysfunction
Breakage, crack
Damage, failure
Insufficient illumination
Starting is difficult
Situation description
Obvious oil leakage, insufficient oil, poor vibration reduction effect due to damage to internal parts or bending of buffer column
Heavy steering or shimmy, which can be basically eliminated through adjustment and maintenance. Repair or replacement can be eliminated
No serious consequences If
only one piece is damaged (not the main piece)
delamination or bubbling
minor cracks, still usable
partial welding, can be welded
slightly loosened, no connection failure
headlamp failure counts as one failure, other lamps cumulatively fail three times count as one failure
cannot meet the requirements of safe driving at night
large area, affecting the appearance
difficult to start
cannot start for two consecutive times or can start after repair without replacing parts. The maximum speed exceeds 40%
the measured value before the test>2.8L/(t·100km）≥84 dB(A)
The acceleration distance measured after the test increases by more than 5%. It can be eliminated without replacing parts
Example of minor fault
Fault mode
Auto-stallation
Improper stroke
Function failure
Damage or falling off
Air blockage or open circuit
Situation description
No fault is caused, easy to eliminate
It can be eliminated after adjustment
The pull rod bolt is loose, easy to eliminate
Easy to eliminate||tt| |There are traces of water seepage when it rains
Minor cracks, still usable
Oil stains, wetwwW.bzxz.Net
No connection failure
1Slightly no expansion
Easy to eliminate without changing parts
Small area, no impact on appearance
Wires and sheaths
Ammeter
Loose chain
Loose belt
Starting performance
Cylinder screw plug
Brake deviation
Water tank float
JB/T 50096-1997
Table A4 (end)
Failure mode
Relatively difficult
Slight deviation
Easy to eliminate
Replace quickly
Situation description
Can be eliminated after adjustment
Can be eliminated after adjustment
Can be started within two times
Can be eliminated after tightening
Can be adjusted and easily eliminated
Can be easily matched
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