1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR1594CAEROSPACEINFORMATION REPORTAIR1594REV. C Issued 1981-08 Revised 2010-07 R
5、eaffirmed 2015-11 Superseding AIR1594B Plain Bearing Selection for Landing Gear Applications RATIONALE AIR1594C has been reaffirmed to comply with the SAE five-year review policy. 1. SCOPE This document is intended to give advisory information for the selection of plain bearings and bearing material
6、s most suitable for aircraft landing gear applications. Information included herein was derived from bearing tests and service experience/reports. Airframe/landing gear manufacturers, commercial airlines, the U.S. Air Force and Naval Air Systems Command provided input for the document.Information is
7、 given on bearing installation methods and fits that have given satisfactory performance and service life. Base metal corrosion is a major cause of problems in bearing installations for landing gears. Therefore, methods of corrosion prevention are discussed. Effort is directed toward minimizing main
8、tenance and maximizing life expectancy of landing gear bearings. Lubricated and self-lubricating bearings are also discussed. There are wide ranges of bearing load and motion requirements for applications in aircraft landing gears. For this reason, it is the responsibility of the designer to select
9、that information which pertains to the particular application. Anti-friction bearings, defined as rolling element bearings generally used in wheel and live axle applications, will not be discussed in this document. Landing gear shock strut bearing design and selection criteria are covered in AIR5883
10、 and, therefore, are not discussed in detail in this document. 1.1 Purpose This document is to be used as a general reference for the aerospace community. 2. REFERENCES The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall
11、apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicab
12、le laws and regulations unless a specific exemption has been obtained. 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.AMS4533 Copper-Beryllium Alloy, Bars a
13、nd Rods 98Cu - 1.9Be Solution and Precipitation Heat Treated (TF00, formerly AT) AMS4534 Copper-Beryllium Alloy, Bars and Rods 98Cu - 1.9Be Solution Heat Treated, Cold Worked, and Precipitation Heat Treated (TH04, formerly HT) AMS4535 Copper-Beryllium Alloy, Mechanical Tubing 98Cu - 1.9Be Solution a
14、nd Precipitation Heat Treated (TF00, formerly AT) AMS4590 Extrusions, Nickel-Aluminum Bronze, Martensitic, 78.5Cu - 10.5Al - 5.1Ni - 4.8Fe, Quenched and Tempered (TQ50) AMS4596 Copper Nickel Tin Alloy, Bars, Rods, and Tubes, 77Cu - 15Ni - 8Sn Solution Annealed and Spinodal Hardened (TX00) AMS4597 Co
15、pper-Nickel-Tin Alloy, Bars and Rods 77Cu - 15Ni - 8Sn Solution Annealed, Cold Finished and Spinodal Hardened (TX TS) AMS4640 Aluminum Bronze, Bars, Rods, Shapes, Tubes, and Forgings 81.5Cu - 10.0Al - 4.8Ni - 3.0Fe Drawn and Stress Relieved (HR50) or Temper Annealed (TQ50) AMS4880 Aluminum Bronze Al
16、loy, Centrifugal and Continuous-Cast Castings 81.5Cu - 10.3Al - 5.0Ni - 2.8Fe Quench Hardened and Temper Annealed (TQ50) AMS4881 Nickel-Aluminum-Bronze, Martensitic, Sand and Centrifugal Castings 78Cu - 11Al - 5.1Ni - 4.8Fe Quench Hardened and Temper Annealed AMS5643 Steel, Corrosion-Resistant, Bars
17、, Wire, Forgings, Tubing, and Rings, 16CR - 4.0Ni - 0.30Cb - 4.0Cu Solution Heat Treated, Precipitation Hardenable AS14101 Bearing, Plain, Self-Lubricating, Self-Aligning, Low Speed, Narrow, Grooved Race, -65 to +325 F AS14102 Bearing, Plain, Self-Lubricating, Self-Aligning, Low Speed, Wide, Chamfer
18、ed Race, -65 to +325 F AS14103 Bearing, Plain, Self-Lubricating, Self-Aligning, Low Speed, Wide, Grooved Race, -65 to +325 F AS14104 Bearing, Plain, Self-Lubricating, Self-Aligning, Low Speed, Narrow, Chamfered Race, -65 to +325 F AS21230 Bearing, Plain, Self-Aligning, Grooved Outer Ringer TFE Lined
19、, Wide AS81820 Bearings, Plain, Self-Aligning, Self-Lubricating, Low Speed Oscillation AS81934 Bearings, Sleeve, Plain and Flanged, Self-Lubricating AS81934/1 Bearing, Sleeve, Plain, Self-Lubricating, -65 F to 325 F AS81934/2 Bearing, Sleeve, Flanged, Self-Lubricating, -65 F to 325 F AS81935 Bearing
20、s, Plain, Rod End, Self-Aligning, Self-Lubricating, General Specification For AS81936 Bearings, Plain, Self-Aligning, (Cu-Be Ball, CRES Race), General Specification For AIR5883 Landing Gears Shock Strut Bearing Selection ARP5935 Use of HVOF Thermal Spray Coatings for Hard Chrome Replacement in Landi
21、ng Gear Applications SAE INTERNATIONAL AIR1594C 2 OF 162.2 ANSI Publications Available from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org.ANSI B4.1 Preferred Limits and Fits for Cylindrical Parts 2.3 ASTM Publications Available f
22、rom ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 15428-2959, Tel: 610-832-9585, www.astm.org.ASTM E 1417 Standard Practice for Liquid Penetrant Testing ASTM E 1444 Standard Practice for Magnetic Particle Testing 2.4 U.S. Government Publications Available from the D
23、ocument Automation and Production Service (DAPS), Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/.MIL-B-8942 Bearings, Plain, TFE Lined, Self-Aligning MIL-B-8943 Bearings, Journal, Plain and Flanged, TFE Lined MIL-PRF-16173 Cor
24、rosion Preventative Compound, Solvent Cutback, Cold - Application MIL-PRF-23827 Grease, Aircraft and Instrument, Gear and Actuator Screw MIL-PRF-32014 Grease, Water Resistant, High Speed, Aircraft and Missile MIL-PRF-81322 Grease, Aircraft, General Purpose, Wide Temperature Range MIL-PRF-81733 Seali
25、ng and Coating Compound, Corrosion Inhibitive MMPDS Metallic Materials Properties Development and Standardization 2.5 Definitions A landing gear bearing is a component which, when installed between two or more landing gear structural members having relative motion, can perform the following function
26、s: a. Transmit loads between those members (moving or stationary). b. Control the friction coefficient of the joint. c. Control the wear of the joint. d. Protect the primary component - act as a sacrificial part. SAE INTERNATIONAL AIR1594C 3 OF 163. PLAIN BEARING CONFIGURATIONS Plain bearings are th
27、ose bearings whose interface motions are sliding actions between two parallel surfaces. Bearings falling within this classification can carry radial and/or thrust loads and accommodate motion. The bearing configurations most widely used in landing gear applications are journal, spherical, and thrust
28、. These bearings can be lubricated or self-lubricating configurations. 3.1 Journal Bearings (Bushings) This configuration consists of a cylindrical shell (with or without a flange) installed in a housing in conjunction with a mating pin or bolt. These bearings are used in pinned joints of landing ge
29、ar mechanisms and structures. They can be highly loaded when there is no joint rotation and less loaded when oscillatory motion is present such as during landing gear retraction and extension. Axially sliding sleeve journals are used in shock struts and hydraulic actuators. Figure 1 is an example of
30、 a typical landing gear journal bearing illustrating both a plain and flanged bearing on the same diagram. FIGURE 1 - TYPICAL LANDING GEAR JOURNAL BEARING 3.2 Spherical Bearings This bearing configuration is an integral unit in which a spherically shaped (ball) inner race is free to rotate and misal
31、ign within the confines of the outer race. The spherical interface will provide for misalignment of joined members and allow for rotary motion. The design will function under both radial and thrust loads. It is desirable for the rotary motion to take placebetween the ball and the outer race of the b
32、earing (lower bearing stress) to avoid galling of the mating pin. To this end, the most common installation, the ball side faces (or bushing sleeve at the ball center) are clamped to the mating pin. The ball may be greased or lined with a low friction material. 3.3 Thrust Bearings Thrust bearings, a
33、s the name implies, are designed to carry thrust loads. Although they may be a separate bearing, they are frequently integrated into a journal bearing as a flanged face. SAE INTERNATIONAL AIR1594C 4 OF 164. LANDING GEAR BEARING CONSIDERATION In the selection of any landing gear bearing or bearing ma
34、terial, the following application parameters must be considered. a. Environmental conditions including exposure to dirt, water or other contaminants b. Applied loads (radial, thrust, moment, static, dynamic, and shock) c. Required service life or service time between overhauls d. Velocity/duration o
35、f relative motion causing frictional heat buildup e. Lubrication requirements f. Misalignment possibilities g. Envelope restrictions h. Type of application (static, oscillatory, slow motion) i. Retention methods j. Position accuracy (radial and axial) k. Maintenance (must be lubricated, repaired or
36、replaced) l. Installation (expansion characteristics, allowable looseness, pre-load requirements) m. Friction, torque (starting and dynamic) n. Weight o. Dissimilar materials (provisions for galvanic action) p. Same materials are avoided for bearings sliding in contact for frictional issues and weld
37、ing potential q. Material selection. Similar materials in contact (such as corrosion resistant alloys) are avoided for galling considerations. However, self-lubricating bearings and mating shafts are made from corrosion resistant alloys since there is a lubricating barrier between the mating surface
38、s. r. Temperature minimum and maximum s. Housing material rigidity and stiffness. t. Running fit per ANSI B4.1. SAE INTERNATIONAL AIR1594C 5 OF 165. MATERIAL SELECTION FOR LUBRICATED BEARINGS Based on experience and laboratory testing, the following materials are those used for bearing applications
39、in landing gears (Reference Tables 1 and 2). The mating pin or shaft wear surface, in most cases, is steel with 0.003 in (0.07 mm) minimum chrome plating or tungsten carbide (WC-Co or WC-Co-Cr) coating thickness. 5.1 Journal and Thrust Bearings There are several materials suitable for lubricated jou
40、rnal bearing use such as aluminum nickel bronze. These journal bearings are often used in conjunction with high strength-chrome plated or WC-Co High Velocity Oxygen Fuel (HVOF) steel pins. Where two journal bearings move relative to one another, aluminum-nickel-bronze is often used in combination wi
41、th Corrosion Resistant Steel (CRES) or equivalent to prevent galling. It has been shown that coating and finish grinding both mating faces with WC-Co HVOF coatings produces excellent wear properties without galling and allows the use of aluminum nickel bronze for both journal bearings, Also, laborat
42、ory tests and service usage indicate that unique journal bearing lubrication grooves improve lubrication properties and minimize wear in service. 5.2 Spherical Bearings There are several materials suitable for lubricated spherical bearing use such as softer metallic outer races with high strength-ch
43、rome plated steel balls. Some materials used are aluminum-nickel-bronze in combination with corrosion resistant steel (CRES) or low alloy steel heat treated to 275 ksi (1896 MPa). Also, laboratory tests and service usage indicate that another satisfactory combination for spherical bearings in the la
44、nding gear environment is a copper beryllium ball with a 17-4 PH CRES outer race (Reference AS81936, Be-Cu spherical bearing). 6. WORKING PRESSURES FOR LUBRICATED BEARINGS 6.1 Working Bearing Pressure The maximum recommended bearing pressures at limit loads generally used for sizing bearings are lis
45、ted in Table 1. Bearing surface roughness at sliding interfaces is commonly 16 to 32 micro-inch (0.4 to 0.8 micro-meter) Ra. Lower Ra values typically produce less wear in service as long as lubrication retention can be assured. Honing is a commonly used method to achieve superior surface finishes i
46、n small bearings. Additional bearing material information is given in Table 2. Aluminum bronze and copper beryllium and similar bearing materials have a higher coefficient of thermal expansion than steel. This characteristic should be considered during the bearing design at limit loads to prevent bi
47、nding at adverse temperatures. Post installation sizing of the bearing inside diameter is used to ensure adequate bearing to pin clearance. 6.2 Thermal Considerations Where high velocity and pressure between the bearing surfaces develops frictional heat in excess of 500 F (260 C), detrimental impact
48、 to landing gear components may occur from frictional burning below a chrome plated journal. In this application, tests have shown that bearings with self-lubricated liners are superior when compared with lubricated metal-to-metal sliding surfaces. Durability of these liners needs to be considered w
49、hen used where high point loads may exist. The leading and trailing edges of such bearings should be chamfered or beveled to prevent peaking or edge loading. HVOF coatings such as WC-Co and WC-Co-Cr have better thermal properties than chrome and, therefore, may reduce the occurrence of frictional burning issues. SAE INTERNATIONAL AIR1594C 6 OF 16TABLE 1 - BEARING DESIGN GUIDE (LUBRICATED) Journal Bearings Spherical Bearings (2
