STANDARDS UPDATE Q4 2025

GEAR STANDARDS DEVELOPMENT UPDATES

This summary updates BGA members an update on developments which are currently taking place in gear standards. If you want to get involved in this process, please contact staff at the BGA for further information.

ISO Technical Committee TC60 is responsible for gear related standards and is supported by the BSI national shadow Technical Committee MCE/5 and other national standards committees around the world. The work of standards development is carried out by Working Groups, convened to work on specific technical areas and tasks. Summarised in the table at this page.

Current projects

There are a large number of projects currently revising ISO standards that may be relevant to your business and are developed by ISO Technical Committee TC60 and the supporting national standards committees around the world.

View all Standards under development by ISO/TC 60/SC1 Nomenclature and wormgearing here.

View all Standards under development by ISO/TC 60/SC2 Gear Capacity Calculation here.

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WG2 Gear accuracy

Following the publication of ISO 1328-2 on cylindrical gear double flank tolerances work has turned to updating the Technical Report that support this document.

However the planned update of ISO 17485 bevel gear tolerance standard, which includes double flank testing tolerances and a project in WG7 to produce a new worm gear tolerance standard is currently making the US and GB consider whether a single tolerance standard could apply to all gears. If you have an opinion on this please contact the BGA and influence which way we develop this.

ISO DTR 10064-2 Code of Inspection Practice – Part 2: Inspection related to radial composite deviations, runout, tooth thickness and backlash.

Currently at the Draft TR stage.

ISO NP 21771-2 new tooth thickness standard

Currently at the being prepared for a Committee Draft stage and formula being reviewed by the WG

Pending projects:

a. ISO/PWI ISO 17485 bevel gear tolerance standard -revision and update required

b. ISO 18653 Gear measuring machine calibration -due for revision and updating.

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WG4 Terminology and notation of gears

This group covers gear wear and damage to teeth terminology as well as gear geometry calculation standards.

ISO DTR 21771-1 Gears and gear pairs- concepts and geometry.

A new project has been created to revise this document.

ISO DTR 21771-2 Gears and gear pairs- concepts and geometry tooth thickness and measurement. Developed in collaboration with WG2.

ISO TR 10825-1 Gears — Wear and damage to gear teeth.

Comments from the FDIS (final draft international standard) are being resolved.

ISO TR 10825-2 Gears — Wear and damage to gear teeth – supplementary information.

A ballot on the Draft TR has been conducted and approved the draft.

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WG6 Gear loading

WG6 is very active. The highest priority is the revision of the worked examples ISO TR 6336-30 that will allow us to verify that when software is updated, we can independently verify the changes have been implemented correctly.

All BGA members can join a BGA Special Interest Group which is currently working through these examples and investigating why different people using the same or sometimes different software get different results.

ISO/DTR 6336-30 Calculation of load capacity of spur and helical gears — Part 30: calculation examples for the application of ISO 6336 Parts 1 ,2, 3, 5

ISO/NP TR 6336-31 Calculation of load capacity of spur and helical gears — Part 31: Calculation examples of micropitting load capacity

ISO/PRF TS 6336-20 Calculation of load capacity of spur and helical gears — Part 20: Calculation of scuffing low capacity (also applicable to bevel hypoid gears) – Flash temperature method

ISO/PRF TS 6336-21 Calculation of load capacity of spur and helical gears — Part 21: Calculation of scuffing load capacity (also applicable to bevel and hypoid gears) – integral temperature method

ISO/NP TS 6336-22 Calculation of load capacity of spur and helical gears — Part 22: Calculation of micropitting load capacity

WG6 also has ad-hoc groups working on other projects which will lead to standards revisions. Currently these include:

a. ISO 6336-1 "Basic principles, introduction and general influence factors"

i. Pitch circle vs reference circle

ii. KHβ Method B

b. ISO 6336-3 "Calculation of tooth bending strength" YF form factor

c. ISO/TS 6336-4 "Tooth Flank Fracture (subsurface initiated fatigue)" example calculations

d. ISO/TR 14179-2 “Gears - Thermal capacity - Part 2: Thermal load carrying capacity”

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WG7 Worm gears

The worm gear group is currently very active and lead by the French delegation and supported by Germany and the rest of the international representatives.

ISO/PWI 7125-1 Cylindrical worm gears - ISO system of flank tolerance classification — Part 1: Definitions of manufacturing specification data, verification parameters, and classification formulas for tooth flanks.

This may become a GPS compatible standard with support from the Italian delegation.

ISO/TR 10828:2015 Revision of ISO/TR 10828:2015 Worm gears Worm profiles and gear mesh geometry for conversion to a full international standard.

Pending projects

a. ISO/TS 14521 worm load capacity standard published in April 2020 change status to a full standard

b. ISO 7125-2 Cylindrical worm gears - ISO system of flank tolerance classification — Part 2: Definitions of manufacturing specification, and classification formulas for double flanks tolerances.