1、 Reference number ISO/TR 18792:2008(E) ISO 2008TECHNICAL REPORT ISO/TR 18792 First edition 2008-12-15 Lubrication of industrial gear drives Lubrification des entranements par engrenages industriels ISO/TR 18792:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with A
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4、are has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2008 All rights reserved. Unless otherwise specified,
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6、tale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedISO/TR 18792:2008(E) ISO 2008 All rights reserved iiiContents Page Foreword. v Introduction . vi 1 Scope . 1 2 Terms and definitions.
7、 1 3 Basics of gear lubrication and failure modes3 3.1 Tribo-technical parameters of gears. 3 3.2 Gear lubricants 5 3.3 Base fluid components 6 3.4 Thickeners . 8 3.5 Chemical properties of additives 9 3.6 Solid lubricants . 10 3.7 Friction and temperature . 10 3.8 Lubricating regime 11 3.9 Lubrican
8、t influence on gear failure. 11 4 Test methods for lubricants 15 4.1 Gear tests 15 4.2 Other functional tests. 16 5 Lubricant viscosity selection 19 5.1 Guideline for lubricant selection for parallel and bevel gears (not hypoid). 19 5.2 Guideline for lubricant selection for worm gears 24 5.3 Guideli
9、ne for lubricant selection for open girth gears 24 6 Lubrication principles for gear units 26 6.1 Enclosed gear units 27 6.2 Open gearing. 34 7 Gearbox service information . 39 7.1 Initial lubricant fill and initial lubricant change period . 39 7.2 Subsequent lubricant change interval 39 7.3 Recomme
10、ndations for best practice for lubricant changes. 40 7.4 Used gear lubricant sample analysis 41 Bibliography . 52 Figures Figure 1 Load and speed distribution along the path of contact. 4 Figure 2 Scraping edge at the ingoing mesh . 5 Figure 3 Schematic diagram of shear effects on thickeners 9 Figur
11、e 4 Mechanisms of surface protection for oils with additives. 11 Figure 5 Examples of gear oil wear test results. 15 Figure 6 Immersion of gear wheels . 27 Figure 7 Immersion depth for different inclinations of the gearbox 29 Figure 8 Immersion of gear wheels in a multistage gearbox . 30 Figure 9 Ex
12、amples of circuit design, combination of filtration and cooling systems . 34 Figure 10 Immersion lubrication 37 ISO/TR 18792:2008(E) iv ISO 2008 All rights reservedFigure 11 Transfer lubrication 37 Figure 12 Circulation lubrication . 38 Figure 13 Automatic spraying lubrication 38 Tables Table 1 Symb
13、ols, indices and units. 1 Table 1 (continued) 2 Table 2 General characteristics of base fluids. 6 Table 3 Example of influence factors on wear . 12 Table 4 Example of influence factors on scuffing load (transmittable torque). 13 Table 5 Example of influence factors on micropitting (transmittable tor
14、que) 14 Table 6 Example of influence factors on pitting (transmittable torque) 14 Table 7 ISO Viscosity grade 1)at bulk oil operating temperature for oils having a viscosity index of 90 2) . 20 Table 8 ISO Viscosity grade 1)at bulk oil operating temperature for oils having a viscosity index of 120 2
15、) . 21 Table 9 ISO Viscosity grade 1)at bulk oil operating temperature for oils having a viscosity index of 160 2) . 22 Table 10 ISO Viscosity grade 1)at bulk oil operating temperature for oils having a viscosity index of 240 2) . 23 Table 11 ISO viscosity grade guidelines for enclosed cylindrical w
16、orm gear drives 24 Table 12 Advantages and disadvantages of various open girth gears lubricants . 25 Table 13 Minimum Viscosity recommendation for continuous lubrication mm 2 /s at 40 C 26 Table 14 Minimum base oil viscosity recommendation for intermittent lubrication mm 2 /s at 40 C 26 Table 15 Typ
17、ical maximum oil flow velocities 33 Table 16 Advantages and disadvantages of greases 35 Table 17 Advantages and disadvantages of oils 35 Table 18 Advantages and disadvantages of lubricating compounds 36 Table 19 Lubrication system selection based on pitch line velocity . 39 Table 20 Lubrication syst
18、em selection based on the type of lubricant. 39 Table 21 Typical recommended lubricant service . 40 Table 22 Examples for an on-line oil condition-monitoring system 40 Table 23 Sources of metallic elements . 47 Table 24 What the ISO codes mean. 49 Table 25 Example of particle size and counts 49 Tabl
19、e 26 Characteristics of particles. 51 ISO/TR 18792:2008(E) ISO 2008 All rights reserved vForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out
20、 through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO col
21、laborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International S
22、tandards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has co
23、llected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not
24、 have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/T
25、R 18792 was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear capacity calculation. ISO/TR 18792:2008(E) vi ISO 2008 All rights reservedIntroduction Gear lubrication is important in all types of gear applications. Through adequate lubrication, gear design and selection of gea
26、r lubricant, the gear life can be extended and the gearbox efficiency improved. In order to focus on the available knowledge of gear lubrication, ISO/TC 60 decided to produce this Technical Report combining primary information about the design and use of lubricants for gearboxes. TECHNICAL REPORT IS
27、O/TR 18792:2008(E) ISO 2008 All rights reserved 1Lubrication of industrial gear drives 1 Scope This Technical Report is designed to provide currently available technical information with respect to the lubrication of industrial gear drives up to pitch line velocities of 30 m/s. It is intended to ser
28、ve as a general guideline and source of information about the different types of gear, and lubricants, and their selection for gearbox design and service conditions. This Technical Report is addressed to gear manufacturers, gearbox users and gearbox service personnel, inclusive of manufacturers and
29、distributors of lubricants. This Technical Report is not applicable to gear drives for automotive transmissions. 2 Terms and definitions For the purposes of this document, the following terms, definitions, symbols, indices and units apply. Table 1 Symbols, indices and units Symbol, index Term Unit A
30、, B, C, D, E points on the path of contact b face width mm C cubic capacity of the oil pump cm 3d diameter mm d a1, 2outside diameter pinion, wheel mm d b1, 2base circle diameter pinion, wheel mm d w1, 2operating pitch diameter pinion, wheel mm f Hcurvature factor N 0,5 /mm 1,5f Lload factor F btcir
31、cumferential load at base circle N n shaftrotational speed of the oil pump driving shaft rpm p pressure bar p Hhertzian stress N/mm 2P gear power kW P vzgear power loss kW P vzsumtotal gearbox power loss kW s slip t time sec ISO/TR 18792:2008(E) 2 ISO 2008 All rights reservedTable 1 (continued) Symb
32、ol, index Term Unit V oil quantity l Q eoil flow l/min Q bearingsoil flow through the bearings l/min Q gearsoil flow through the gear mesh l/min Q pumpoil pump flow l/min Q sealsoil flow through the seals l/min v pitch line velocity m/s v 1, 2surface velocity pinion, wheel m/s v gsliding velocity m/
33、s v tpitch line velocity m/s v sum velocity m/s V tankoil tank volume l z 1number of pinion teeth helix angle degree relation between the calculated film thickness and the effective surface roughness 2.1 intermittent lubrication intermittent common lubrication of gears which are not enclosed NOTE Ge
34、ars that are not enclosed are referred to as open gears. 2.2 manual lubrication hand application periodical application of lubricant by a user with a brush or spout can 2.3 centralized lubrication intermittent lubrication of gears by means of a mechanical applicator in a centralized system 2.4 conti
35、nuous lubrication continuous application of lubricant to the gear mesh in service 2.5 splash lubrication bath lubrication immersion lubrication dip lubrication process, in an enclosed system, by which a rotating gear or an idler in mesh with one gear is allowed to dip into the lubricant and carry it
36、 to the mesh ISO/TR 18792:2008(E) ISO 2008 All rights reserved 32.6 oil stream lubrication pressure-circulating lubrication forced-circulation lubrication continuous lubrication of gears and bearings using a pump system which collects the oil in a sump and recirculates it 2.7 drop lubrication use of
37、 oil pump to siphon the lubricant directly onto the contact portion of the gears via a delivery pipe 2.8 spray lubrication process in oil stream lubrication by which the oil is pumped under pressure to nozzles that deliver a stream or spray onto the gear tooth contact, and the excess oil is collecte
38、d in the sump and then returned to the pump via a reservoir 2.9 spray lubrication for open gearing continuous or intermittent application of lubricant using compressed air 2.10 oil mist lubrication process by which oil mist, formed from the mixing of lubricant with compressed air, is sprayed against
39、 the contact region of the gears NOTE It is especially suitable for high-speed gearing. 2.11 brush lubrication process by which lubricant is continuously brushed onto the active tooth flanks of one gear 2.12 transfer lubrication continuous transferral of lubricant onto the active tooth flanks of a g
40、ear by means of a special transfer pinion immersed in the lubricant or lubricated by a centralized lubrication system 3 Basics of gear lubrication and failure modes 3.1 Tribo-technical parameters of gears 3.1.1 Gear types There are different types of gear such as cylindrical, bevel and worm. The typ
41、e of gear used depends on the application necessary. Cylindrical gears with parallel axes are manufactured as spur and helical gears. They typically have a line contact and sliding only in profile direction. Cylindrical gears with skewed axes have a point contact and additional sliding in the axial
42、direction. Bevel gears with an arbitrary angle between their axes without gear offset have a point contact and sliding in profile direction. They generally have perpendicular axes and are manufactured as straight, helical or spiral bevel gears. Bevel gears with gear offset are called hypoid gears wi
43、th point contact and sliding in profile and axial directions. Worm gears have crossed axes, line contact and sliding in profile and mainly axial direction. 3.1.2 Load and speed conditions The main tribological parameters of a gear contact are load, pressure, and rolling and sliding speed. A static l
44、oad distribution along the path of contact as shown in Figure 1 can be assumed for spur gears without profile ISO/TR 18792:2008(E) 4 ISO 2008 All rights reservedmodification. In the zone of single tooth contact the full load is transmitted by one tooth pair, in the zone of double tooth contact the l
45、oad is shared between two tooth pairs in contact. 1Key 1 spur gear without profile correction Figure 1 Load and speed distribution along the path of contact The static load distribution along the path of contact can be modified through elasticity and profile modifications. Due to the vibrational sys
46、tem of the gear contact, dynamic loads occur as a function of the dynamic and natural frequency of the system. A local Hertzian stress for the unlubricated contact can be derived from the local load and the local radius of curvature (see Figure 1). When a separating lubricating film is present, the
47、Hertzian pressure distribution in the contact is modified to an elastohydrodynamic pressure distribution with an inlet ramp, a region of Hertzian pressure distribution, possibly a pressure spike at the outlet and a steep decrease from the pressure maximum to the ambient. The surface speed of the fla
48、nks changes continuously along the path of contact (see Figure 1). The sum of the surface speeds of pinion and wheel represents the hydrodynamically effective sum velocity; half of this value is known as entraining velocity. The difference of the flank speeds is the sliding velocity, which together
49、with the frictional force results in a local power loss and contact heating. Rolling without sliding can only be found in the pitch point with its most favourable lubricating conditions. Unsteady conditions with changing pressure, sum and sliding velocity along the path of contact are the result. In addition, with each new tooth coming into contact, the elastohydrodynamic film must be formed anew under often unfavourable conditions of the scraping
