ISO 6336-1:2019

Overview

ISO 6336-1:2019 (identical to ISO 6336-1:2019) defines the basic principles, introduction and general influence factors for calculating the load capacity of spur and helical gears. Part 1 sets out the conceptual framework and influence factors used throughout the ISO 6336 series to establish a uniform, engineering-validated method for rating cylindrical gears with straight or helical involute teeth. It is intended for experienced gear designers rather than the general engineering public.

Key topics and technical requirements

• Scope and applicability
  • Applies to cylindrical spur and helical gears with normal pressure angles from 15° to 25°, helix angles up to 30°, and transverse contact ratios 1.0 to 2.5. Results outside these ranges require empirical confirmation.
  • Not applicable when transverse contact ratio < 1.0, interference exists, teeth are pointed, or backlash is zero.
  • Not applicable to teeth finished by forging or sintering, gears with poor contact patterns, or for some deterioration modes (e.g., plastic deformation, case crushing, general wear) and unpredictable vibratory conditions.
• Influence factors and conventions
  • Defines and explains general influence factors used in rating: application factor (K), internal dynamic factor, face load factors (Kβ, Fβ), transverse load factors (Kα, Fα) and others.
  • Describes assumptions, numerical formulae, factor succession and implied accuracy for calculations.
• Failure modes covered by the series
  • Provides the framework for evaluating pitting (surface durability), tooth root breakage, tooth flank fracture, scuffing, and micropitting (with guidance that abrasive wear dominates at pitch line velocities below 1 m/s).
• Methodology
  • Presents methods and validation sources (testing and theoretical studies) and clarifies that parts of the ISO 6336 series are not interchangeable unless explicitly referenced.

Practical applications

• Use ISO 6336-1 as the foundational reference when performing gear load capacity calculations, comparing alternative gear designs, or developing gear-rating software.
• Typical applications include gear design and analysis in power transmission systems, gearbox component specification, failure-risk assessment and pre-testing validation for industrial, automotive and machinery gearsets.
• Helps experienced gear designers select appropriate factor values based on similar designs and operational experience.

Who should use this standard

• Experienced gear designers and drivetrain engineers
• Gear calculation and simulation engineers
• Test laboratories validating gear performance
• Standards committees and technical authors working on gear-rating methods

Related standards

• ISO 6336 series (other parts referenced for specific failure modes and methods): ISO 6336-2 (pitting), ISO 6336-3 (tooth root breakage), ISO/TS 6336-4 (tooth flank fracture), and additional technical reports (e.g., ISO/TS 6336-20/21/22 for scuffing and micropitting guidance).

Keywords: ISO 6336-1:2019, ISO 6336, gear load capacity, spur gears, helical gears, pitting, tooth root breakage, micropitting, scuffing, face load factor, dynamic factor.