IPC Definitions - January 01, 2012
F16H 57/033 - Definition
This group covers:
A group of similar gearboxes based on the same design, e.g. being available in different sizes.
A group of gearboxes which comprises a combination of several standardised units and which can meet various requirements by altering the combination of such units.
(see the figures below)
(US5404772A)