1、MILITARY SPECIFICATION MIL-B-8948A 30 November 1972 SUPERSEDING MIL-B-8948( ASG) 25 JULy 1967 BEARINGS, PLAIN:, ROD END, TFE LINED, SELF-ALIGNING This specification is approved for use by all Departaents and Agencies of the Departaent of Defense. 1. SCOPE 1.1 Scope - This specification covers plain
2、rod end bearings which are self-aligning and self-lubricating by incorporating tetra fluoreethy1ene (TFE) in a liner between the inner ring (ball) outer ring (race) for use in the tEilperature range -650 F to +2500 F. 1.2 Classification - Bearings shall be of the following classes, as specified (see
3、 6.2): Class 1 Externally threaded shank Class 2 Internally threaded shank 2. APPLICABLE roCUMENTS 2.1 The folloving documents, of the issue in effect on date of invitation for bids or request for proposal, fora a part of this specifi cation to the extent specified herein: SPECIFICAllONS Federal QQ-
4、P-416 Military MIL-B-197 MIL-I-6868 Plating, Cadmium (Electrodeposi ted) Bearings, Anti-Friction, Associated Parts and Subass_blies ,P“a.ckaging of Inspection Process, Magnetic Particle FSC 3120 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-8
5、948A MIL-S-8879 MIL-B-7838 MIL-B-8942 MIL-D-10OO STANDARDS Military MIL-STD-105 MIL-STD-129 MS2l230 MS2l24,2 MS21243 Scre Threads, Controlled Radius Root with Increased Minor Diameter; General Specification for Belt J Internal Wrenching, 160 KSI FTU Bearings, Plain, TFE Lined, Self-Aligning Drawing,
6、 Engineering, ,and Assocj,.ated List Sampling Procedures and Tables :or Inspection by Attributes Marking for Shipnent and Storagj Bearing; Plain, Self-Aligning, Grooved Outer Ring, TFE Lined, Wide Bearing, Plain, Rod End, Self-Aligning, TFE Lined, Externally Threaded Bearing, Plain, Rod End, Self-Al
7、igning, TFE Lined, Internally Threaded (Copies of specifications, standards, draings, and publications required by suppliers in connection th specific procurement fUnctions should be obtained from the procuring activity or as directed by tbe contracting officer.) 2.2 Other publications - The followi
8、ng documents form a prt of this specification to the extent specified herein. Unless otherwise indicated, the issue in effect on date of invitation for bids or rElquest for proposal shall apply. American National Standards Institute ANSI B46.1 - Surface Texture (Surface Roughness, Waviness and Lay)
9、Copies of the above publication may be obtained fran the Ameri()an National Standards Institute, 1430 Broadway, New York, N.Y. 10018,) Uniform Classification Committee Uniform Freight Classification Rules (Application for copies of the above publication should be addressed to the Uniform Classificat
10、ion Committee, 202 Chicago Union Station, Chicage, Ill. 60606. ) 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-8948 A 3. QUIRJiMENTS 3.1 Qualification - The bearings furnished under this speci-fication shall be a product hich is in accordan
11、ce th the applicable Military Standard (MS), and contains a bearing cartridge in accordance th MS2l230 that has been qualified to MIL-B-8942, and hich has been subjected to and hich has passed the qualification tests specified herein, and hich has been listed on or approved for listing on the applic
12、able Qualified Products List. 3.1.1 Product design change - Any change in product design or description ll require requalification of the product to an extent determined by the activity responsible for qualification. 3.2 Material - The ball and race shall be in accordance i th MS21230. The rod end b
13、ody materials shall be in accordance ith MS2l242 or MS2l243. The liner shall include TFE in such manner that i t ll conform to all the requirements of MIL-B-8942 and this specification. 3.2.1 Plating - Cadmium plating shall be in accordance ith QQ-P-416, type I, class 2. 3.3 Design - Bearing design
14、shall conform to MS2l242 and MS2l243. 3.4 Construction - Construction shall be such that all relative motion ll be beteen the liner and the ball. The bearing shall not have loading slots. Except as otheise specified, the details of the orking parts shall be optional. 3.4.1 Dimensions and tolerances
15、- Dimensions and tolerances shall be as specified on the applicable MS. Dimensions not shown shall be at the option of the manufacturer. 3.4.2 Surface texture - Surface fiDishes shall be in accordance th the applicable MS and ANSI B46.1. Bearings shall be free of any defects which may be detrimental
16、 to satisfactory installation, perform ance or bearing life, as defined by this specification. 3.4.3 Lubrication - Initial lubrication by the manufacturer ll be permitted. Relubrication ll not be permitted. Threads -3.4.4.1 Class 1 rod ends - Threads shall be rolled before or after heat treatment an
17、d conform to MIL-S-8879. Opi tonal thread runout shall be in accordance ith MIL-B-7838. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.4.4.2 Class 2 rod ends - Threads shall conform to MIL-S-88i9. 3.5 Perfom.ance -3.5.1 Ultillate static load - N
18、o fracture of the bearing smul occur when the ultimate static load specified on the applicable r:)(i end MS is applied in accordance with 4.6.1. 3.5.2 Axial static proof load - No pushout of the bearing ridge frca the rod end body shall occur when the axlal proof load on th( appli cable MS is applie
19、d as spec1fied in 4.6.2. 3.5.3 Fatigue load - The rod end bearings shall be capable of wi thstand1ng a lIiniDlum of 50,000 cycles of loading when tested in accordance with 4.6.3. 3.5.4 Se1f-aligpmept - The bearing shall be selt-aligning and perait the angular disp1acEllent specified on the applicabl
20、e rod end MS. 3.5.5 No-load rotational breakaway torgue - When tested ill accordance with 4.6.4, the no-load breakaway torque shall be within the liaits of the values spec1fied on the applicable rod end MS. 3.6 Interchangeability - All parts baving the same lBanuf“acturers part JlUIIlber shall be di
21、rectly and ccmp1ete1y interchangeable with each other with respect to installation and performance. The drawing number requir.ents of MIL-D-lOOO shall govern changes in the manutactu:r“ers part nuabers. 3.7 Identification of product - Each bear shall be lU.rked wi th the aili tary identifying part n
22、umber and the manufacturers ll8IIle . or tradamar.k, and manufacturers part number prefixed by (MFR). Where practicable, identification shall appear on the side face of the rod end body; otherwise identification shall appear on the periphery of 1he rod end body. Metal impression stamping shall not b
23、e pend tted. 3.8 Workmanship - The bearing shall be free of toolJlarJaI, chatter vaves, rust, grinding scratches, pits, or any other defects that .ay ad versely affect their serviceability. 4. QUALITY ASSURANCE PROVISIONS 4.1 ReSponsibility for inspection - Unless othe:rwi.se spicified in the contra
24、ct or purchase order, the supplier is responsible t:)r the perto1“llance of all inspection requirEllents as spec1fied herein. Except as otherw-1se specified, the supplier may utilise his own facilit:les or any other camaercial laboratory acceptable to the Government. The Govern .ent reserves the rig
25、ht to perf 0111 any ot the inspections set forth in the spec1fication where such inspections are deElllled necessary to assure sup plies aDd services“cenfora to prescri requirements. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4.1.1 8lification
26、 test records - The manufacturer shall main tain a record showing quantitative results for all tests required bl this specification. This record shall be available to the purchaser and shall be signed by an authorised. representative of the manufacturer or the testing laboratory, as applicable. 4.2
27、Classification of inspection - The examination and testing of the bearings shall be classified as: (a) Qualification inspection (4.3) (b) Qualitl conformance inspection (4.4) 4.3 Qualification inspections -4.3.1 Sampling instructions - Qualification inspection samples shall consist of 10 bearings of
28、 the - 6, - 8, and -12 sizes ot each class (1 and 2), for which qualification is desired. All bearings necessary for tests specified herein shall be turnished by the manufacturer. When approved, the - 6, - 8, and -12 sizes ot a class will qu81ify the - 3 through -16 sizes of that class. Samples shal
29、l be identified as required and forwarded to the activitl designated in the letter of authorisation tram the activitl responsible for qualification (see 6.3). 4.3.2 Certified test report - The manufacturer shall turnish a certified test report showing that the manufacturers product satisfac torill c
30、onforms to this specification. The test report shall include, as a w1nimum, actual results of the tests specified herein. When the report is subrl tted, it shall be accClllpanied bl a dated drawing which caapletell describes the manufacturers product by specifying all dimen sions and tolerances, com
31、position of the ball and outer race material, lubricant if used, coating or plating, and heat treatment. The manufac turers part number tor each size shall be included on the drawing. 4.3.3 Inspections - Qualification inspections shall include all the examinations and tests of this specification. Th
32、e minblum number of samples per test shall be in accordance with table I. TABLE I. Qualification inspection s_ples 1nation and test Paragraph No. Samples to be tested Examination of product 4.5.1 5 Preparation for delivery 4.5.2 5 U1 timate static load 4.6.1 3 Axial static proof load 4.6.2 1/3 Fatig
33、ue load 4.6.3 3 11 Qualification of class 1 will qualifl class 1 and class 2. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4.4 Quality conformance inspections - The quality confo:mance inspections of the bearings shall consist of the following exa
34、mililations and tests to determine conformance of the bearings to the requirDents of this specification and the applicable MS with regard to: (a) Dimensions (b) Identification of product ( c) Workmanship (d) Preparation for delivery ( e) No-load breakaway torque (f) Hardness (g) Magnetic particle in
35、spection 4.4.1 Inspections - The bearing manufacturer shall be responsible for accomplishing the quality conformance inspections specified herein. 4.4.2 - The lot definition, formation, and size shall be in accordance with MIL-STD-105. 4.4.3 Sampling - The sample bearings shall be selected in accord
36、-ance with MIL-STD-105, inspection level II, acceptable quality level of 1.0 percent, except that inspection for no-load breakaway tOrqUE I and .agnetic or penetrant inspection of the rod end body shall be 100 percent. 4.5 Examinations -4.5.1 Examination of product - The bearings shall be exmllined
37、to determine conformance to the requirements of this specification and the applicable MS for material, plating, dimenSions, finish, identHication of product, workmanship, and requirements not covered by tests. 4.5.2 Inspection of preparation for delivery - Preservation, packaging, packing, . and mar
38、king shall be inspected to determine confOlll the w1n1mum torque required to start the ball aoving shall be recorded. The no-load rotational breakaway torque shall be as specified on the applicable MS. !he ball shall be hand rotated through several revolutions immediately prior to testing. 4.6.5 Har
39、dness - !he bearings shall be tested for hardness using a standard Rockwell hardness tester. Readings for the rod end body shall be taken on the nat at the head shaDk junction. 4.6.6 Magnetic particle ingp8ctiOP - Alloy steel rod end bodies shall be inspected in accordance with MIL-I-6868. !he inspe
40、ction shall be by both the longitudinal and circular methods. Certification of such inspection shall be furnished with qualification s_ples ad quality conformance tests. 5. PREP !RATION FOR DELIVERY 5.1 Clean1pg. preservation, and packaging -5.1.1 Level A - Cleaning, preservation, and packagiDg shal
41、l be in accordance with level A of MIL-B-l97. 5.1.2 Level C - CleaDing, preservation, and packaging shall be in accordance with the contractors caaaercial practice. 5.2 Pacldng -5.2.1 Leyel A - Bearings, cleaned, preserved, and packaged as specified in 5.1.1, shall be packed for overseas shipaent in
42、 accordance with MIL-B-197. 5.2.2 Level B - Bearings, cleaned, preserved, and packaged as specifiecl in 5.1.1 shall be packed for dan tic shipaent aDd storage in. accordance with MIL-B-l97. 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5.2.3 Leve
43、l C - Bearings, cleaned, preserved, and packaged as specified in 5.1.2, shall be packed in a manner to insure carrier accep tance and safe delivery at destination. The containers shall be In accordance od th the Uniform Freight Classif“ica.tion BuIes or regulltions of other carriers, as applicable t
44、o the mode of transportation. 5.3 Marking of shiments - Interior packages and exteriojl ship-ping containers shall be marked in accordance with MIL-STD-l29. Ibe nomenclature shall include: BEARINGS, PLAIN, ROD END, WE LIlfED, SELF-ALIGNING 6. NOTES 6.1 Intended use - These bearings are intended prim
45、arily for use in airframe applications of highlo8ds at low rotational oscillatory speeds. For specific design information on the capability of these bearings under particular load, speed and wear/life conditions the user is referred to The Airframe Design Guide. 6.2 Ordering data - Procurement docum
46、ents should specify: (a) Title, number, and date of this specification. (b) MS part number (see 3.3). (c) Class of bearing (see 1.2). (d) Applicable levels of preservation, packaging, 8Ild packing (see 5.1 and 5.2). 6.3 Qualification - With respect to products requiring 1.:uali-fication, awards will
47、 be made only for such products as have, prlor to the time set for opening of bids, been tested and approved for ulclusion in the applicable Qualified Products List, whether or not such pl“oducts have actually been so listed that date. The attention of the sup pliers is called to this requir_ent, an
48、d manufacturers are urged to arrange to have the products that they propose to offer to the FEderal Government tested for qualification in order that they may be eU.gible to be awarded contracts or orders for the products covered by thl:.s specification. The activity responsible for the Qualified Pr
49、oduc:ts List is the Naval Air Systems Command, Navy Department, Washington, D.,C. 20360; however, information pertaining to qualification of producjts may be obtained from the Naval Air Deve10paent Center, AND, Code Kmi!l, Warminster, Penneyl vania 18974. 6.3.1 Qualification tests will be authorised only upon prlsentation of certified t
