ISO/TC 60 - Gears

This document provides nomenclature for general modes of gear tooth wear and failure. It classifies, identifies, and describes the most common types of failure and provides information that, in many cases, enables the user to identify failure modes and evaluate the degree or change from original condition. This document is based on experience with steel gears; however, many of the failure modes discussed apply to gears made from other materials. Not all failure modes that can occur on other types of gears, such as plastic, bronze, or powder metal gears, are included. The solution to many gear problems requires detailed investigation and analysis by specialists and is beyond the scope of this document. This document specifies only the terminology intended to help with the identification and reporting of the appearance and conditions of gears after a period of operation. Neither causes nor preventive measures for any condition described are discussed. In this document, gear refers to both gear wheels and pinions, unless the gear is specifically identified. This document does not define “gear failure”.

This document specifies the integral temperature method for calculating the scuffing load capacity of cylindrical gears.

This document specifies methods and formulae for evaluating the risk of scuffing, based on Blok's contact temperature concept. The fundamental concept is applicable to all machine elements with moving contact zones. The flash temperature formulae are valid for a band-shaped or approximately band-shaped Hertzian contact zone and working conditions characterized by sufficiently high Péclet numbers.

This document provides calculation examples for different bevel gear designs regarding the scuffing load capacity according to ISO/TS 10300-20. The initial geometry data of the gear necessary for these calculations are in accordance with ISO 23509. The term "bevel gear" is used to mean straight, helical (skew), spiral bevel, zerol and hypoid gear designs. Where this document pertains to one or more, but not all, the specific forms are identified. The formulae in this document are based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of εvα

This document provides a calculation method for bevel and hypoid gears regarding scuffing based on experimental and theoretical investigation[7]. This calculation method is a flash temperature method. The formulae in this document are intended to establish uniformly acceptable methods for calculating scuffing resistance of straight, helical (skew), spiral bevel, Zerol and hypoid gears made of steel. They are applicable equally to tapered depth and uniform depth teeth. Hereinafter, the term “bevel gear” refers to all of these gear types; if not the case, the specific forms are identified. A calculation method of the scuffing load capacity of bevel and hypoid gears based on an integral temperature method is not available when this document is published. The formulae in this document are based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of εvα

This document specifies requirements for the accuracy of general-purpose hobs of 0,5 module to 40 module. These hobs are intended for producing gears which conform to ISO 53 and ISO 54. This document applies to hobs for spur and helical gears. It applies to solid (monobloc) and inserted blade hobs. The elemental features of hobs are graded according to accuracy, as follows: — Grade 4A; — Grade 3A; — Grade 2A; — Grade A; — Grade B; — Grade C; — Grade D. Grade 4A is the highest order of precision. In addition to the elemental tests for hobs, this document gives permitted tolerances for composite tests that are taken along the cutting edges on the line of action. The two groups of tests are not equivalent and one can choose between one or the other. If there was no previous agreement, the hob is regarded as belonging to the precision class specified if it satisfies one or the other of the two methods of inspection. NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.

This document specifies formulae for calculating the load capacity of cylindrical worm gears and covers load ratings associated with wear, pitting, worm deflection, tooth breakage and temperature. Scuffing and other failure modes are not covered by this document. The load rating and design procedures are only valid for tooth surface sliding velocities, , less than or equal to 25 m/s and contact ratios greater than 2,1. For wear, load rating and design procedures are only valid for tooth surface sliding velocities which are above 0,1 m/s. The rules and recommendations for the dimensioning, lubricants or materials selected by this document only apply to centre distances of 50 mm and larger. For centre distances below 50 mm, method A applies. The choice of appropriate methods of calculation requires knowledge and experience. This document is intended for use by experienced gear designers who can make informed judgements concerning factors. It is not intended for use by engineers who lack the necessary experience. See 4.7. WARNING — The geometry of worm gears is complex, therefore the user of this document is encouraged to make sure that a valid working geometry has been established.

This document establishes a gear tooth classification system relevant to double flank radial composite deviations of individual cylindrical involute gears and sector gears. It specifies the appropriate definitions of gear tooth deviations, the structure of the gear tooth flank classification system, and the allowable values of the gear tooth deviations. It provides formulae to calculate tolerances for individual product gears when mated in double flank contact with a master gear. Tolerance tables are not included. This document is applicable to gears with three or more teeth that have reference diameters of up to 600 mm. This document does not provide guidance on gear design nor does it recommend tolerances.

This document presents the basic principles of, an introduction to, and the general influence factors for the calculation of the load capacity of spur and helical gears. Together with the other documents in the ISO 6336 series, it provides a method by which different gear designs can be compared. It is not intended to assure the performance of assembled drive gear systems. It is not intended for use by the general engineering public. Instead, it is intended for use by the experienced gear designer who is capable of selecting reasonable values for the factors in these formulae based on the knowledge of similar designs and the awareness of the effects of the items discussed. The formulae in the ISO 6336 series are intended to establish a uniformly acceptable method for calculating the load capacity of cylindrical gears with straight or helical involute teeth. The ISO 6336 series includes procedures based on testing and theoretical studies as referenced by each method. The methods are validated for: — normal working pressure angle from 15° to 25°; — reference helix angle up to 30°; — transverse contact ratio from 1,0 to 2,5. If this scope is exceeded, the calculated results will need to be confirmed by experience. The formulae in the ISO 6336 series are not applicable when any of the following conditions exist: — gears with transverse contact ratios less than 1,0; — interference between tooth tips and root fillets; — teeth are pointed; — backlash is zero. The rating formulae in the ISO 6336 series are not applicable to other types of gear tooth deterioration such as plastic deformation, case crushing and wear, and are not applicable under vibratory conditions where there can be an unpredictable profile breakdown. The ISO 6336 series does not apply to teeth finished by forging or sintering. It is not applicable to gears which have a poor contact pattern. The influence factors presented in these methods form a method to predict the risk of damage that aligns with industry and experimental experience. It is possible that they are not entirely scientifically exact. Therefore, the calculation methods from one part of the ISO 6336 series is not applicable in another part of the ISO 6336 series unless specifically referenced. The procedures in the ISO 6336 series provide rating formulae for the calculation of load capacity with regard to different failure modes such as pitting, tooth root breakage, tooth flank fracture, scuffing and micropitting. At pitch line velocities below 1 m/s the gear load capacity is often limited by abrasive wear (see other literature such as References [23] and [22] for further information on such calculation).

This document specifies the fundamental formulae for use in tooth bending stress calculations for involute external or internal spur and helical gears with a rim thickness sR > 0,5 ht for external gears and sR > 1,75 mn for internal gears. In service, internal gears can experience failure modes other than tooth bending fatigue, i.e. fractures starting at the root diameter and progressing radially outward. This document does not provide adequate safety against failure modes other than tooth bending fatigue. All load influences on the tooth root stress are included in so far as they are the result of loads transmitted by the gears and in so far as they can be evaluated quantitatively. This document includes procedures based on testing and theoretical studies such as those of Hirt[11], Strasser[14] and Brossmann[10]. The results are in good agreement with other methods (References [5], [6], [7] and [12]). The given formulae are valid for spur and helical gears with tooth profiles in accordance with the basic rack standardized in ISO 53. They can also be used for teeth conjugate to other basic racks if the virtual contact ratio εαn is less than 2,5. The load capacity determined on the basis of permissible bending stress is termed "tooth bending strength". The results are in good agreement with other methods for the range, as indicated in the scope of ISO 6336‑1. If this scope does not apply, refer to ISO 6336-1:2019, Clause 4.

This document specifies the information and standardized conditions necessary for the calculation of the service life (or safety factors for a required life) of gears subject to variable loading for only pitting and tooth root bending strength. If this scope does not apply, refer ISO 6336-1:2019, Clause 4.

This document specifies the fundamental formulae for use in the determination of the surface load capacity of cylindrical gears with involute external or internal teeth. It includes formulae for all influences on surface durability for which quantitative assessments can be made. It applies primarily to oil‑lubricated transmissions, but can also be used to obtain approximate values for (slow‑running) grease‑lubricated transmissions, as long as sufficient lubricant is present in the mesh at all times. The given formulae are valid for cylindrical gears with tooth profiles in accordance with the basic rack standardized in ISO 53. They can also be used for teeth conjugate to other basic racks where the actual transverse contact ratio is less than εαn = 2,5. The results are in good agreement with other methods (see References [5], [7], [10], [12]). These formulae cannot be directly applied for the assessment of types of gear tooth surface damage such as plastic yielding, scratching, scuffing and so on, other than that described in Clause 4. The load capacity determined by way of the permissible contact stress is called the "surface load capacity" or "surface durability". If this scope does not apply, refer to ISO 6336-1:2019, Clause 4.

This document supplements ISO 1328‑1:2013. It provides a code of practice dealing with measurements on flanks of individual cylindrical involute gears, i.e. with the measurement of pitch, profile, helix and tangential composite characteristics. It describes measuring equipment, provides advice for gear measuring methods and for the analysis of measurement results, and discusses the interpretation of results. Measurements using a double flank tester are not included (see ISO/TR 10064‑2). This document only applies to involute gears.

This document describes a procedure for the calculation of the tooth flank fracture load capacity of cylindrical spur and helical gears with external teeth. It is not intended to be used as a rating method in the design and certification process of a gearbox. The formulae specified are applicable for driving as well as for driven cylindrical gears while the tooth profiles are in accordance with the basic rack specified in ISO 53. They can also be used for teeth conjugate to other racks where the actual transverse contact ratio is less than εα = 2,5. The procedure was validated for case carburized[15] gears and the formulae of this document are only applicable to case carburized gears with specifications inside the following limits: — Hertzian stress: 500 N/mm2 ≤ pH ≤ 3 000 N/mm2; — Normal radius of relative curvature: 5 mm ≤ ρred ≤ 150 mm; — Case hardening depth at 550 HV in finished condition: 0,3 mm ≤ CHD ≤ 4,5 mm. This document is not applicable for the assessment of types of gear tooth damage other than tooth flank fracture.

The example calculations presented here are provided for guidance on the application of the technical specification ISO/TS 6336‑22 only. Any of the values or the data presented should not be used as material or lubricant allowables or as recommendations for micro-geometry in real applications when applying this procedure. The necessary parameters and allowable film thickness values, λGFP, should be determined for a given application in accordance with the procedures defined in ISO/TS 6336‑22.

This document describes a procedure for the calculation of the micropitting load capacity of cylindrical gears with external teeth. It has been developed on the basis of testing and observation of oil-lubricated gear transmissions with modules between 3 mm and 11 mm and pitch line velocities of 8 m/s to 60 m/s. However, the procedure is applicable to any gear pair where suitable reference data are available, providing the criteria specified below are satisfied. The formulae specified are applicable for driving as well as for driven cylindrical gears with tooth profiles in line with the basic rack specified in ISO 53. They are also applicable for teeth conjugate to other basic racks where the virtual contact ratio (εαn) is less than 2,5. The results are in good agreement with other methods for normal working pressure angles up to 25°, reference helix angles up to 25° and in cases where pitch line velocity is higher than 2 m/s. This document is not applicable for the assessment of types of gear tooth surface damage other than micropitting.

ISO/TR 10300-30:2017 provides sample calculations for different bevel gear designs, how the load capacity is numerically determined according to the methods and formulae of the ISO 10300 series. The initial geometric gear data necessary for these calculations in accordance with ISO 23509. The term "bevel gear" is used to mean straight, helical (skew), spiral bevel, zerol and hypoid gear designs. Where this document pertains to one or more, but not all, the specific forms are identified. The manufacturing process of forming the desired tooth form is not intended to imply any specific process, but rather to be general in nature and applicable to all calculation methods of the ISO 10300 series. The fact that there are bevel gear designs with tapered teeth and others where the tooth depth remains constant along the face width (uniform depth) does not demand to apply Method B2 for the first and Method B1 for the second tooth configuration. The rating system of the ISO 10300 series is based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of εvα

ISO/TR 6336-30:2017 presents worked examples that apply exclusively the approximation methods for the determination of specific influential factors, such as the dynamic factor, Kv, and the load distributions factors KHα, KHβ, etc., where full analytical calculation procedures are provided within the referenced parts of ISO 6336. Worked examples covering the more advanced analysis techniques and methods are outside the scope of this document. The example calculations presented in this document are provided for guidance on the application of ISO 6336‑1, ISO 6336‑2, ISO 6336‑3 and ISO 6336‑5. Any of the values, safety factors or the data presented are not to be taken as recommended criteria for real gearing. Data presented within this document are for the purpose of aiding the application of the calculation procedures of ISO 6336‑1, ISO 6336‑2, ISO 6336‑3 and ISO 6336‑5.

ISO 14104:2017 specifies procedures and requirements for the detection and classification of localized overheating on ground surfaces by chemical etch methods. The process described in this document is typically used on ground surfaces; however, it is also useful for the detection of surface anomalies that result from post-heat treatment machining such as hard turning, milling and edge breaking (deburring) processes. Surface metallurgical anomalies caused by carburization or decarburization are also readily detectable with this process. Some methods which have been used in the past are no longer recommended. Specifications are intended to be changed to use the methods in this document. These etching methods are more sensitive to changes in surface hardness than most hardness testing methods. ISO 14104:2017 applies to steel parts such as gears, shafts, splines and bearings. It is not applicable to nitrided parts and stainless steels. NOTE This process, although at times called "nital etch", is not intended to be confused with other processes also known as "nital etch". The surface temper etch procedure is performed after grinding and before additional finishing operations such as superfinishing, shot peening and honing.

ISO 23509:2016 specifies the geometry of bevel gears. The term bevel gears is used to mean straight, spiral, zerol bevel and hypoid gear designs. If the text pertains to one or more, but not all, of these, the specific forms are identified. The manufacturing process of forming the desired tooth form is not intended to imply any specific process, but rather to be general in nature and applicable to all methods of manufacture. The geometry for the calculation of factors used in bevel gear rating, such as ISO 10300 (all parts), is also included. ISO 23509:2016 is intended for use by an experienced gear designer capable of selecting reasonable values for the factors based on his/her knowledge and background. It is not intended for use by the engineering public at large. Annex A provides a structure for the calculation of the methods provided in this document.

ISO 6336-5:2016 describes contact and tooth-root stresses and gives numerical values for both limit stress numbers. It specifies requirements for material quality and heat treatment and comments on their influences on both limit stress numbers. Values in accordance with ISO 6336-5:2016 are suitable for use with the calculation procedures provided in ISO 6336‑2, ISO 6336‑3 and ISO 6336‑6 and in the application standards for industrial, high-speed and marine gears. They are applicable to the calculation procedures given in ISO 10300 for rating the load capacity of bevel gears. ISO 6336-5:2016 is applicable to all gearing, basic rack profiles, profile dimensions, design, etc., covered by those standards. The results are in good agreement with other methods for the range indicated in the scope of ISO 6336‑1 and ISO 10300‑1.

ISO 16904:2016 specifies the design, minimum safety requirements and inspection and testing procedures for liquefied natural gas (LNG) marine transfer arms intended for use on conventional onshore LNG terminals, handling LNG carriers engaged in international trade. It can provide guidance for offshore and coastal operations. It also covers the minimum requirements for safe LNG transfer between ship and shore. Although the requirements for power/control systems are covered, this International Standard does not include all the details for the design and fabrication of standard parts and fittings associated with transfer arms. ISO 16904:2016 is supplementary to local or national standards and regulations and is additional to the requirements of ISO 28460. ISO 16904:2016 needs not be applied to existing facilities.

ISO/TR 10828:2015, thread profiles of the five most common types of worms at the date of publication are described and formulae of their axial profiles are given. The five worm types covered in this technical report are designated by the letters A, C, I, K and N. The formulae to calculate the path of contact, the conjugate profile of the worm wheel, the lines of contact, the radius of curvature and the velocities at points of contact are provided. At the end the application of those formulae to calculate parameters used in load capacity calculations are provided.

ISO 16961:2015 specifies the minimum requirements for surface preparation, materials, application, inspection and testing of internal coating lining systems that are intended to be applied on internal surfaces of steel storage tanks of crude oil, hydrocarbons and water for corrosion protection. It covers both new construction and maintenance works of tank internal coating and lining as well as the repair of defective and deteriorated systems. ISO 16961:2015 also provides the minimum requirements for shop performance testing of the coated/lined samples and the criteria for their approval.

ISO 16903:2015 gives guidance on the characteristics of liquefied natural gas (LNG) and the cryogenic materials used in the LNG industry. It also gives guidance on health and safety matters. It is intended to act as a reference document for the implementation of other standards in the liquefied natural gas field. It is intended as a reference for use by persons who design or operate LNG facilities.

ISO/TS 16901:2015 provides a common approach and guidance to those undertaking assessment of the major safety hazards as part of the planning, design, and operation of LNG facilities onshore and at shoreline using risk-based methods and standards, to enable a safe design and operation of LNG facilities. The environmental risks associated with an LNG release are not addressed in this Technical Specification.

ISO 10300-1:2014 specifies the methods of calculation of the load capacity of bevel gears, the formulae and symbols used for calculation, and the general factors influencing load conditions. The formulae are intended to establish uniformly acceptable methods for calculating the pitting resistance and bending strength of straight, helical (skew), spiral bevel, Zerol and hypoid gears. They are applicable equally to tapered depth and uniform depth teeth. The term "bevel gear" refers to all of these gear types; if not the case, the specific forms are identified. The formulae take into account the known major factors influencing pitting on the tooth flank and fractures in the tooth root. The rating formulae are not applicable to other types of gear tooth deterioration such as plastic yielding, micropitting, case crushing, welding, and wear. The bending strength formulae are applicable to fractures at the tooth fillet, but not to those on the active flank surfaces, to failures of the gear rim or of the gear blank through the web and hub. Pitting resistance and bending strength rating systems for a particular type of bevel gears can be established by selecting proper values for the factors used in the general formulae. If necessary, the formulae allow for the inclusion of new factors at a later date. The rating system of ISO 10300 (all parts) is based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of εvα

ISO 10300-2:2014 specifies the basic formulae for use in the determination of the surface load capacity of straight and helical (skew), Zerol and spiral bevel gears including hypoid gears, and comprises all the influences on surface durability for which quantitative assessments can be made. ISO 10300-2:2014 is applicable to oil lubricated bevel gears, as long as sufficient lubricant is present in the mesh at all times. The formulae in ISO 10300-2:2014 are based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of Ɛvα

ISO 10300-3:2014 specifies the fundamental formulae for use in the tooth root stress calculation of straight and helical (skew), Zerol and spiral bevel gears including hypoid gears, with a minimum rim thickness under the root of 3,5 mmn. All load influences on tooth root stress are included, insofar as they are the result of load transmitted by the gearing and able to be evaluated quantitatively. Stresses, such as those caused by the shrink fitting of gear rims, which are superposed on stresses due to tooth loading, are intended to be considered in the calculation of the tooth root stress, σF, or the permissible tooth root stress σFP. ISO 10300-3:2014 is not applicable in the assessment of the so-called flank breakage, a tooth internal fatigue fracture (TIFF). The formulae in ISO 10300-3:2014 are based on virtual cylindrical gears and restricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of Ɛvα

ISO 1328-1:2013 establishes a tolerance classification system relevant to manufacturing and conformity assessment of tooth flanks of individual cylindrical involute gears. It specifies definitions for gear flank tolerance terms, the structure of the flank tolerance class system, and allowable values. ISO 1328-1:2013 provides the gear manufacturer and the gear buyer with a mutually advantageous reference for uniform tolerances.

IEC 61400-4:2012(E) is applicable to enclosed speed increasing gearboxes for horizontal axis wind turbine drivetrains with a power rating in excess of 500 kW. This standard applies to wind turbines installed onshore or offshore. It Standard provides guidance on the analysis of the wind turbine loads in relation to the design of the gear and gearbox elements. The gearing elements covered by this standard include such gears as spur, helical or double helical and their combinations in parallel and epicyclic arrangements in the main power path. The standard is based on gearbox designs using rolling element bearings. Also included is guidance on the engineering of shafts, shaft hub interfaces, bearings and the gear case structure in the development of a fully integrated design that meets the rigours of the operating conditions. Lubrication of the transmission is covered along with prototype and production testing. Finally, guidance is provided on the operation and maintenance of the gearbox.

ISO/TR 22849:2011 provides information for the application of bevel and hypoid gears using the geometry in ISO 23509, the capacity as determined by ISO 10300 (all parts) and the tolerances in ISO 17485. ISO/TR 22849:2011 provides additional information on the application, manufacturing, strength and efficiency of bevel gears for consideration in the design stage of a new bevel gear set.

Concerns the part of the international vocabulary of gears which is devoted solely to geometrical definitions. It gives, for each of the geometrical terms relative to gears, a standard definitions which will be valid internationally, to corresponding term in each langauge being chosen as far as possible in such a way as to directly reflect the meaning of the definition.

ISO/TR 10064-6:2009 provides information on measuring methods and practices of unassembled bevel and hypoid gears and gear pairs. It includes methods and practices, which permit the manufacturer and purchaser to conduct measuring procedures which are accurate and repeatable to a degree compatible with the specified tolerance grade of ISO 17485. Tolerances are given in Clause 5 of ISO 17485:2006, for calculating the maximum values allowed by the specific tolerance grade. Required and optional measuring methods are provided in Clause 6 of ISO 17485:2006. ISO/TR 10064-6:2009 applies to bevel gear components as defined in ISO 17485. It does not apply to enclosed gear unit assemblies, including speed reducers or increasers, gear motors, shaft mounted reducers, high speed units, or other enclosed gear units which are manufactured for a given power, speed, ratio or application.

ISO/TR 18792:2008 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 serve 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.

ISO 2490:2007 specifies the nominal dimensions of general-purpose single-start solid (monobloc) gear hobs with axial keyway or tenon drive of 0,5 to 40 module. These hobs are intended for the production of gears which conform to ISO 54:1996 and present a 20° pressure angle in conformity with ISO 53:1998.

ISO 21771:2007 specifies the geometric concepts and parameters for cylindrical gears with involute helicoid tooth flanks. Flank modifications are included. It also covers the concepts and parameters for cylindrical gear pairs with parallel axes and a constant gear ratio, which consist of cylindrical gears according to it. Gear and mating gear in these gear pairs have the same basic rack tooth profile.

Provides recommended values for dimensional deviations on blanks, centre distance and parallelism of axes of gears. Numerical values given in this document are not to be regarded as strict ISO quality criteria, but may serve as a guide for mutual agreements, for steel or iron components.

Provides recommendations on measurement considerations for surface roughness and tooth contact pattern checking of gear flanks.

Constitutes a code of practice dealing with inspection relevant to radial composite deviations, runout, tooth thickness and backlash of cylindrical involute gears; i.e. with measurements referred to double flank contact.

This part of ISO/TR 10064 provides additional information and examples to support the implementation of ISO 18653. It proposes evaluation and calibration procedures for involute, helix, pitch, runout, and tooth thickness measurement processes. Methods are given for evaluation of the condition and alignments of instrument elements such as centres, guideways, probe systems, etc. Recommendations are included for establishment of a proper environment and for statistical data evaluation procedures. It also covers the application of gear artifacts to the estimation of U95 measurement process uncertainty. Guidance on the application of measurement processes to the inspection of product gears is provided, including fitness for use and the recommended limits for U95 uncertainty based upon the accuracy tolerances of product gears to be inspected. Many of its recommendations may also be applicable to the measurement of worms, worm wheels, bevel gears and gear cutting tools.

ISO 17485:2006 establishes a classification system that can be used to communicate geometrical accuracy specifications of unassembled bevel gears, hypoid gears, and gear pairs. It defines gear tooth accuracy terms, and specifies the structure of the gear accuracy grade system and allowable values. ISO 17485:2006 provides the gear manufacturer and the gear buyer with a mutually advantageous reference for uniform tolerances. Ten accuracy grades are defined, numbered 2 to 11 in order of decreasing precision. ISO 17485:2006 does not apply to enclosed gear unit assemblies, including speed reducers or increasers, gear motors, shaft mounted reducers, high speed units, or other enclosed gear units manufactured for a given power, speed, ratio or application. Gear design is beyond the scope of ISO 17485:2006. The use of the accuracy grades for the determination of gear performance requires extensive experience with specific applications. Therefore, the users of this International Standard are cautioned against the direct application of tolerance values to a projected performance of unassembled (loose) gears when they are assembled.

ISO 14635-3:2005 specifies a test method based on an FZG four-square test machine for determining the relative load-carrying capacity of semi-fluid gear greases defined by the gear surface damage known as scuffing. This method is useful for evaluating the scuffing load capacity potential of semi-fluid gear greases of NLGI classes 0 to 000, typically used with highly stressed gearing for enclosed gear drives. It can only be applied to greases giving a sufficient lubricant flow in the test gear box of the FZG test machine.

ISO/TR 10064-5:2005 provides additional information and examples to support the implementation of ISO 18653. It proposes evaluation and calibration procedures for involute, helix, pitch, runout, and tooth thickness measurement processes. Methods are given for evaluation of the condition and alignments of instrument elements such as centres, guideways, probe systems, etc. Recommendations are included for establishment of a proper environment and for statistical data evaluation procedures. It also covers the application of gear artefacts to the estimation of U95 measurement process uncertainty. Guidance on the application of measurement processes to the inspection of product gears is provided, including fitness for use and the recommended limits for U95 uncertainty based upon the accuracy tolerances of product gears to be inspected. Many of its recommendations may also be applicable to the measurement of worms, worm wheels, bevel gears and gear cutting tools

ISO 14635-2:2004 specifies a test method based on an FZG four-square test machine for determining the relative load-carrying capacity of high EP oils defined by the gear surface damage known as scuffing. The method is useful for evaluating the scuffing load capacity potential of oils typically used with highly stressed cylindrical gearing found in many vehicle and stationary applications. It is not suitable for establishing the scuffing load capacity potential of oils used in highly loaded hypoid bevel gearing applications, for which purpose other methods are available in the industry.

ISO 18653:2003 specifies methods for the evaluation of measuring instruments used for gear measurements of involute, helix, pitch and runout. It is applicable both to instruments that measure runout directly and to those that compute it from index measurements. It also gives recommendations for the evaluation of tooth thickness measuring instruments and, of necessity, includes the estimation of measurement uncertainty with the use of calibrated gear artifacts. It does not address the calibration of artifacts by laboratories accredited in accordance with ISO 17025; nor are its requirements intended as an acceptance specification of product gears (see ISO 1328-1, ISO 1328-2, ISO/TR 10064-1 and ISO/TR 10064-2). The estimation of product gear measurement uncertainty is beyond its scope (see ISO/TR 10064-5 for recommendations).

This part of ISO 8579 specifies the instructions and standardized conditions necessary for the determination of the airborne sound emission of gear units and gearmotors. It also specifies the allowed measurement methods, together with the operating and mounting conditions used for the test. This part of ISO 8579 has the aim of ensuring, with its use, the reproducibility of the determination of the airborne sound emission characteristics within specified limits determined by the grade of accuracy of the basic measurement method used. The sound measurement methods allowed by this part of ISO 8579 are engineering methods (grade 2) and survey methods (grade 3).

The formulae specified in this International Standard are intended to establish a uniformly acceptable method for calculating the pitting resistance and bending strength capacity of industrial gears with spur or helical teeth. The rating formulae in this International Standard are not applicable to other types of gear tooth deterioration such as plastic yielding, micropitting, scuffing, case crushing, welding and wear, and are not applicable under vibratory conditions where there may be an unpredictable profile breakdown. The bending strength formulae are applicable to fractures at the tooth fillet, but are not applicable to fractures on the tooth working profile surfaces, failure of the gear rim, or failures of the gear blank through web and hub. This International Standard does not apply to teeth finished by forging or sintering. It is not applicable to gears which have a poor contact pattern. This International Standard provides a method by which different gear designs can be compared. It is not intended to assure the performance of assembled drive gear systems. Neither is it intended for use by the general engineering public. Instead, it is intended for use by the experienced gear designer who is capable of selecting reasonable values for the factors in these formulae based on knowledge of similar designs and awareness of the effects of the items discussed. CAUTION — The user is cautioned that the calculated results of this International Standard should be confirmed by experience.

This International Standard specifies the minimum requirements for enclosed, precision, single and double helical, one- and two-stage speed increasers and reducers of parallel shaft design with pinion speeds of 3000 min−1 or greater, or pitch line velocities of 25 m/s or greater, for special purpose applications. Such applications will typically be required to operate continuously for extended periods, without installed spare equipment and are critical to the continued operation of the installation. By agreement this International Standard may be used for other services. This International Standard also specifies a method of rating gears which meet the following criteria: a) gear accuracy  teeth accuracy: accuracy grade 4 or better as given in ISO 1328-1:1995, for both single pitch deviation, fpt, and total cumulative pitch deviation, Fp,  total helix deviation Fβ between the helices of the pinion and wheel: accuracy grade 4 or better as given in ISO 1328-1:1995; b) range of the transverse contact ratios: 1,2 c) overlap ratio εβ W 1,0; d) helix angle: 5 u β u 35°; e) working flanks of the pinion or gear: provided with profile modifications to obtain a good conjugate tooth load distribution along the path of contact; f) working flanks of pinion or gear: modified as necessary to compensate for both torsional and bending deflections and, when necessary for gears with pitch line velocities in excess of 100 m/s, also for thermal distortions; g) gear lubrication: straight mineral oil, viscosity grade VG-32 or VG-46 (see ISO 3448); h) material of the gear teeth: quality MQ or better, in accordance with ISO 6336-5:1996.

This part of ISO/TR 14179 utilizes an analytical heat balance model to provide a means of calculating the thermal transmittable power of a single- or multiple-stage gear drive lubricated with mineral oil. The calculation is based on standard conditions of 25 °C maximum ambient temperature and 95 °C maximum oil sump temperature in a large indoor space, but provides modifiers for other conditions.