This International Standard specifies the nominal dimensions and tolerances which affect the interchangeability between flywheels and spring-loaded single- or two-plate clutches. The flywheels are for use on reciprocating internal combustion engines in conjunction with flywheel housings and clutch housings which are dealt with in ISO 7648[1] and ISO 7649[2]. Dimensions and tolerances not specified are left to the discretion of the component manufacturer. This International Standard applies to reciprocating internal combustion engines, with the exception of engines for aircraft and passenger cars; it may be used for other engine applications where no specific International Standard exists. NOTE — It is recognized that the dimensions shown in this International Standard may not be suitable for some designs in use at present, but they should be used for all new designs as a means of achieving rationalization in the future.