ISO TR 15144-1-2014 PDF

Full title and description

Calculation of micropitting load capacity of cylindrical spur and helical gears — Part 1: Introduction and basic principles. This technical report gives a procedure for calculating the load capacity of external cylindrical gears with respect to micropitting, including the principal formulae, assumptions, applicability limits and basic guidance for application.

Abstract

ISO/TR 15144-1:2014 describes a calculation procedure for the micropitting load capacity of cylindrical gears (spur and helical) developed from tests on oil‑lubricated gear transmissions. The method is based on comparing the minimum specific lubricant film thickness in the contact region with a permissible specific film thickness and provides formulae and limits of applicability (modules, pitch line velocities, pressure and helix angles, contact ratio conditions). The report is explicitly limited to micropitting and does not address other types of gear tooth surface damage.

General information

• Status: Withdrawn.
• Publication date: 2014-09 (Edition 2).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 21.200 (Gears).
• Edition / version: Edition 2 (2014).
• Number of pages: 35 pages (ISO bibliographic record).

Scope

Provides a procedure to calculate micropitting load capacity for cylindrical gears with external teeth. The method was developed from test data on gears with modules roughly 3 mm to 11 mm and pitch line velocities in the 8 m/s to 60 m/s range, but can be applied to other gear pairs when appropriate reference data are available and the specified criteria are met. Applicable to driving and driven gears with tooth profiles based on the basic rack given in ISO 53 and to conjugate teeth where the virtual contact ratio is less than 2.5. The method is not intended for assessment of gear surface damage modes other than micropitting.

Key topics and requirements

• Definition and description of micropitting and its effect on gear performance (surface appearance, propagation, influence on accuracy, noise and dynamic loads).
• Calculation of minimum specific lubricant film thickness in the contact zone (λGF,min) and definition of permissible specific film thickness (λGFP).
• Definition of the safety factor against micropitting (ratio of λGF,min to λGFP) and guidance on interpretation.
• Formulae and parameters required: gear geometry (module, helix angle, contact ratio), operating conditions (pitch line velocity, loads, temperature), lubricant properties and surface roughness inputs.
• Limits of applicability and recommended ranges (pressure angles, helix angles, pitch line velocity, virtual contact ratio) and cautionary notes where the method may not be valid.
• Worked examples and reference guidance are provided in the companion part covering calculation examples (separate document).

Typical use and users

Used by gear designers, drivetrain and gearbox manufacturers, tribologists, reliability and maintenance engineers, test laboratories and researchers to assess and reduce risk of micropitting in gear systems, to support design choices (surface finish, lubricant selection, micro‑geometry) and to benchmark calculated safety factors during development and failure analysis.

Related standards

Mainly superseded and incorporated into the ISO 6336 series: ISO/TS 6336-22:2018 (Calculation of micropitting load capacity) replaces ISO/TR 15144-1:2014; the companion example calculations originally in ISO/TR 15144-2:2014 were replaced by ISO/TR 6336-31:2018. Other related references include ISO 53 (basic rack/profile) and the broader ISO 6336 family on gear load capacity and strength assessment.

Keywords

micropitting, gears, cylindrical gears, spur gears, helical gears, load capacity, lubricant film thickness, specific film thickness, gear design, ISO 53, contact ratio, pitch line velocity, gear surface damage

FAQ

Q: What is this standard?

A: ISO/TR 15144-1:2014 is a technical report that provided a calculation procedure and basic principles for assessing micropitting load capacity of cylindrical spur and helical gears. It has been withdrawn and its content carried forward into newer ISO/TS and ISO/TR documents.

Q: What does it cover?

A: It covers the theory and formulae for determining minimum and permissible specific lubricant film thicknesses, the safety factor against micropitting, required input parameters (geometry, operating conditions, lubricant and surface data) and limits of applicability; it is limited to micropitting and not other surface failure modes.

Q: Who typically uses it?

A: Gear designers, gearbox manufacturers, tribologists, test laboratories, maintenance and reliability engineers, and researchers use the method to predict micropitting risk and inform design or corrective actions.

Q: Is it current or superseded?

A: ISO/TR 15144-1:2014 is withdrawn. Its calculation method was superseded and published in ISO/TS 6336-22:2018 (and related example materials moved to ISO/TR 6336-31:2018). Users should consult the ISO/TS 6336 series for the current technical specification.

Q: Is it part of a series?

A: Yes — it formed part of the ISO/TR 15144 set (part 1: principles, part 2: examples) and its material has since been integrated into the ISO 6336 series (parts addressing micropitting calculation and examples).

Q: What are the key keywords?

A: Micropitting; specific film thickness; safety factor; cylindrical gears; spur and helical; pitch line velocity; gear micro‑geometry; lubricant properties; ISO 53; ISO 6336.