BGA Member Standards Update We would like to draw your attention to corrections to ISO 4156-1 & 3 published in 2021 which were addressed in corrigenda (corrections) in December 2025. ISO 4156-3:2021 Straight cylindrical involute splines — Metric module, side fit. Part 3- Inspection An error in Figure 6 for external splines has been corrected in the update and, more importantly, an error in a sign in formula (9) for internal splines has been corrected has been corrected as sho

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 deve