What is BS 978-2 - Cycloidal gear specification about?

The cycloidal gear profile is a form of toothed gear used in mechanical clocks, rather than the involute gear form used for most other gears. BS 978 is a British Standard series that discusses specifications for fine pitch gears.

BS 978-2 is the second part of the BS 978 multi-series, and applies to cycloidal type spur gears for spring or weight-driven mechanisms in which:

The pinion is the driven member
The pinion is required to act sometimes as the driver and sometimes as the driven member

Note: For integrating electricity meters the particular form of gear specified herein is not necessary and it is recognized that other existing forms of gear will continue to be used.

Who is BS 978-2 - Cycloidal gear specification for?

BS 978-2 on cycloidal gear specification is useful for:

Manufacturers and suppliers of gear cutters
Manufacturers and suppliers of machines with gears
Manufacturers of cycloidal gears
Product design teams/innovation teams
Production / mechanical engineers
Quality control personnel
Users of cycloidal gears

Why should you use BS 978-2 - Cycloidal gear specification?

In cycloidal gears, the addenda of the wheel teeth are convex epi-cycloidal and the addenda of the pinion are concave hypocycloidal curves generated by the same generating circle. This ensures that the motion of one gear is transferred to the other at locally constant angular velocity.

BS 978-2 walks you through aspects such as the normal modules, terminology and notation, form of tooth, tolerances, and cutters of gears.

Detailed diagrams and tables have been provided in BS 978-2 to illustrate the shapes and dimensions of cycloidal gears.

BS 978-2 guidelines help you to follow best practices when designing and manufacturing pitch gears. This lets you demonstrate the efficiency and reliability of your cycloidal gears.

BS 978-2:1952

Specification for fine pitch gears - Cycloidal type gears

Current

Published:

24 Jan 1952