BS 978-2:Addendum No. 1:1959

This standard BS 978-2:Addendum No. 1:1959 Gears for instruments and clockwork mechanisms. Cycloidal type gears. is classified in these ICS categories:

• 21.200 Gears

This specification relates to spur and helical gears with pitches of 0.15 to 0.7 mm module inclusive, the basic rack of the system having a normal tooth profile composed of two circular arcs.

Basic rack tooth shape and modules from 0.150 mm to 0.700 mm inclusive. Limits of tolerance for tip diameter, pitch, tooth thickness, profile, axial and radial run-out and centre distance; cutters for pinions with from six to twelve teeth.