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Main technical contents of this standard are equivalent to U.S. AAR M211-92 Purchase and Acceptance of Couplers and Coupler Yokes for Freight Service, AAR M205-79 Test Requirements for Coupler Yoke and AAR M201-92 Steel Castings.
Annexes A and B of this standard are normative.
This standard was proposed by the Ministry of Railways of the People's Republic of China.
This standard is under the jurisdiction of Qishuyan Locomotive & Rolling Stock Technology Research Institute, Ministry of Railways.
Purchase and Acceptance of Couplers and Couplers Yokes for Freight Service
1 Scope
This standard specifies the requirements for purchase and acceptance of couplers, coupler parts and coupler yokes for railway freight cars.
This standard is applicable to couplers, coupler parts and coupler yokes for railway freight car made of Grades C and E steel, and is also applicable to locomotive couplers.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, all editions indicated are valid. All standards are subject to revision, and the parties coming to an agreement based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards below.
GB/T 229-1994 Metallic Materials - Charpy Notch Impact Test
GB/T 6803-1986 Standard Method for Conducting Drop Weight Test to Determine Nil Ductility Transition Temperature of Ferritic Steels
GB/T 8363-1987 Metallic Materials; Drop-weight Tear Tests of Ferritic Steels
GB/T 9444-1988 The Methods for Magnetic Particle Testing and for Specifying Quality Levels of Steel Castings
TB/T 1583-1996 Technical Specification for Repair Welding of Steel Castings for Rolling Stock
TB/T 1669-1985 Gauge for No.13 Coupler
TB/T 2594-1996 Low Alloy Cast Steel for General Structure of Rolling Stock
TB/T 2604-1996 Gauge for No.13 Coupler Yoke
AAR M118-91 Coupler Knuckle Pin and Yoke Key
3 Technical Requirements
3.1 Couplers and coupler yokes shall be manufactured in accordance with this standard and the product drawings approved by the Ministry of Railways.
3.2 Manufacturer's approval
All coupler and coupler yoke manufacturers shall get approval of competent department of Ministry of Railways.
During approval application, the manufacturer shall submit the result of first two groups of periodic test specified in 4.3. See normative Annex A for the submitted data format.
3.3 Material requirements
3.3.1 Grades C and E steel castings shall be subjected to quenching and tempering thermal treatment (normalizing and tempering thermal treatment is allowed for Grade C steel castings??).
3.3.2 The tensile property of specimen prepared by Grades C and E steel keel block shall meet the requirements of TB/T 2594.
3.3.3 The specimen prepared by the casting shall at least reach 80% of the tensile strength and yield strength required in TB/T 2594.
3.3.4 Fracture toughness test shall be carried out on the specimen prepared by casting. Fracture toughness test contents are nil-ductility transition temperature test or dynamic tear test. Nil-ductility transition temperature test is carried out according to GB/T 6803 and dynamic tear test is carried out by reference to GB/T 8363. The nil-ductility transition temperature of Grades C and E steel shall be lower than or equal to -56℃.
The purpose of fracture toughness test and impact test is to assess and monitor the property of steel casting. Where the specimen is defective, the obtained test result shall be rejected and resample shall be conducted for test. The rejection of single test will not be regarded as rejection of such steel. The manufacturer shall carry out research for each kind of rejected test and take corrective measures. Re-testing is permissible.
3.3.5 Low-temperature impact property of steel casting at -40℃ shall meet the following requirements:
Impact absorbing energy of Grade C steel is not less than 34J;
Impact absorbing energy of Grade E steel is not less than 27J.
V-notched specimen in accordance with GB/T 229 shall be used for impact test.
3.4 Hardness
3.4.1 The hardness of coupler knuckle shall meet the following requirements:
Grade C steel 179~229;
Grade E steel 241~291.
3.4.2 The hardness of steel castings other than coupler knuckle shall meet the following requirements:
Grade C steel 179~241;
Grade E steel 241~311.
See Figures 1 for the hardness measuring position on castings.
4 Test Requirements
4.1 The purpose of the following tests is to assess and monitor the property of steel castings. Where the specimen is defective, the obtained test result shall be rejected and resample shall be conducted for test; the rejection of single test will not be regarded as rejection of such steel. The manufacturer shall carry out research for each kind of rejected test and take corrective measures. Re-testing is permissible.
4.2 Perfectness of casting
4.2.1 The perfectness of casting shall be controlled by the enterprise standard and quality assurance procedure of manufacturer. Randomly take a sample from 5000 couplers, coupler knuckles and coupler yokes or from the products manufactured in six months for strength test. If in specified period, the output of a kind of product is less than 1000 pcs, it is unnecessary to carry out such test in this period. However, regardless of any condition, each kind of products manufactured shall be tested at least one time every year. The sample must represent the product in actual production at that time. For each kind of product, if the strength tests for continuous 10 times are acceptable, the manufacturer may reduce the frequency of strength test to one time every year. But after the test frequency is reduced, and the test for one time is rejected not because of sample defect, then the manufacturer shall reestablish basic conditions for continuous 10 times of acceptable tests prior to reducing the test frequency.
4.2.2 Strength test
The permanent deformation of coupler body, coupler knuckle and coupler yoke, the minimum fracture load of coupler body and coupler knuckle and the minimum limit load of coupler yoke must meet the requirements of Table 1. Figures 2 and 2a show the measurement positions of permanent deformation dimension.
4.2.3 Internal compactness
4.2.3.1 For each kind of coupler body, coupler knuckle and coupler yoke, at least one sample is dissected at the early stage of production and every six months afterwards, so as to determine whether the manufacturer has the capability of meeting the compactness requirements. Each sample shall be selected from different melting furnace No. If in such period, the output of a kind of products is less than 1000 pcs, it is unnecessary to carry out such dissection. However, regardless of the output, each kind of product shall be dissected at least one time every year. If the dissection results of two years are acceptable, the manufacturer may reduce the dissection frequency of casting to one time every year for each kind of product. Where the casting process has significant change, the casting shall also be dissected for inspection.
After the frequency of dissection inspection is reduced, and the result of dissection inspection for one time is rejected, then the manufacturer shall reestablish basic conditions for acceptable dissection test results of two years prior to reducing the test frequency of dissection inspection.
Table 1
Parts name Grade C steel Grade E steel
Maximum permanent deformation /mm Minimum fracture load Minimum limit load Maximum permanent deformation /mm Minimum fracture load Minimum limit load
At 1335kN At 2000kN kN At 1780kN At 3115kN kN
Coupler knuckle 1) 0.8 — 2950 0.8 — 3430
Coupler body — 0.8 3225 — 0.8 4005
Coupler yoke2) — 0.8 3225 0.8 at 3340kN 4005
1) Simulated coupler knuckle clamp is adopted during the test.
2) Minimum limit load of coupler yoke refers to the load deforming the coupler yoke to make it clamp the buffer box. During the test, the deformation of coupler yoke must not exceed 6.4mm.
4.2.3.2 Casting shall be dissected in accordance with the positions specified in Figures 3, 3a and 3b. The positions for assessment of defect severity are also listed in Figures 3, 3a and 3b.
4.2.3.3 The defect severity at the assessment position of casting shall be assessed according to Annex B (Normative) "Standard Reference Picture for Casting Compactness" and the assessment result shall be recorded.
4.2.3.4 The severity of defect assessed on each profile shall not exceed the grade specified in Table 2.
Foreword i
1 Scope
2 Normative References
3 Technical Requirements
4 Test Requirements
5 Repair Welding
6 Coupler Knuckle Pin and Yoke Pin
7 Casting Mass
8 Sample Plate Inspection
9 Coupler Operation
10 Casting Finishing
11 Lubrication
12 Labelling
13 Acceptance Criteria of Casting
14 Inspection by the Purchaser
15 Additional Requirements
Annex A (Normative) Test Report of Chemical Components and Mechanical Property Conducted According to 3.3, GB/T 17425-
Annex B (Normative) Standard Reference Picture of Steel Casting Compactness
