National Physical Laboratory

New resources for the renewable energy industry

The NPL root fillet artefact set
The NPL root fillet artefact set

Two new Good Practice Guides, a gear root fillet artefact set and an e-Learning course have been produced by NPL to support manufacturers of large drive train components.

Renewable energy is becoming a large part of UK energy generation capacity. Much of this energy is generated by wind farms, and so the reliability and lifetime of wind turbines is becoming increasingly important. Although rare, one of the main causes of turbine downtime is the failure of components in the drive train (gears, bearings, shafts and brakes). These failures can be linked to the surface texture and dimensional form of these mechanical components.

Good Practice Guides

NPL has produced two Good Practice Guides which cover the measurement of the surface texture of large gears and bearings to provide an outline of best practice to the drive train industry. The guides cover the effects of surface texture on the performance and lifetime of the components and recommend measurement techniques that will provide reliable measurement results, and consequently increase confidence in quality control procedures. The guides are written for users who are familiar with surface texture measurement but not with the specific challenges of measuring gears and bearings.

Download the Good Practice Guide on the Surface Texture Measurements of Gear Surfaces Using Stylus Instruments

Download the Good Practice Guide on Measurement of the Surface Texture of Large Roller Bearings

Gear root fillet artefact

A gear root fillet artefact set has also been produced. The form of the root fillet is important as it affects bending stress. If the root fillet is smaller than specified premature gear tooth breakage due to bending fatigue can occur, leading to a catastrophic failure of the gearbox, costly repairs and loss of power generation capacity. Each artefact in the set consists of two root fillets, one of which is a pure radius and the other a trochoid, a common shape for a gear root fillet which has a varying radius around the fillet region. The full root fillet radius is a simple partial arc and is thus a well-understood measurand for which uncertainty assessment is well-documented. By including both root fillet forms on a single artefact, the additional uncertainty caused by measuring the varying radius in the trochoidal root form can be quantified. The artefact can be measured using a traditional gear measuring machine, a coordinate measuring machine or an optical or contacting type form measuring machine.

Enquire about the NPL root fillet artefact

e-Learning course

In addition to these resources an e-Learning course providing an overview of the metrology of large drive train components has been produced. This introductory course draws upon the knowledge of the entire ENG56 collaboration to cover the basics of wind turbine and drive train structure, the common mechanical problems which occur and measurement strategies for the key components. The course is available for free on the NPL website.

Register for the Drivetrain components e-Learning course

Additional resources

The production of the Good Practice Guides, e-Learning course and root fillet artefact set was supported by the European Metrology Research Program Project ENG56: DriveTrain, an international collaboration involving several National Measurement Institutes and universities. Good Practice Guides and measurement artefacts for other aspects of drive train metrology have been produced by many of the other collaborators, and are available from the ENG56 website

NPL's Dimensional measurement experts provide a wide range of services, facilities and advice to support UK manufacturing and science. In addition to offering this support, the group undertakes state-of-the-art research to develop the measurement standards and services of the future.

Find out more about NPL's Dimensional Research

Contact: Dimensional Enquiries

Keep in touch with the latest news and events at NPL
by signing up for an email newsletter

Last Updated: 6 Oct 2017
Created: 11 Sep 2017


Please note that the information will not be divulged to third parties, or used without your permission