ISO 1275:2006

ISO 1275.2006 specifies requirements for double-pitch precision roller chains suitable for the mechanical transmission of power and for conveyors, together with those for their associated sprockets. It covers dimensions, tolerances, length measurement, preloading and minimum tensile strengths.
These double-pitch chains have been derived from some of the short-pitch transmission precision roller chains covered by ISO 606 having certain common dimensions but of double the pitch.
The chains are intended for use under less onerous conditions with respect to speed and power transmitted than are the base chains from which they are derived.
ISO 1275.2006 primarily applies to sprockets with 5 to 75 teeth inclusive (with intermediate numbers of teeth 5 and a half to 74 and a half inclusive).
The preferred numbers of teeth are 7, 9, 10, 11, 13, 19, 27, 38 and 57.