The standard design of the forced lubrication for gear units up tosize 12 is provided with a coarse filter.Upon request, the design can have a filter with a filter chamber(line filter) or also with 2 filter chambers (dual changeover filter).These two filters have an electronic contamination indicator.With a dual changeover filter, the operator can "switch over" froma dirty filter element to a clean one during operation, whichmakes the gear unit 100% available. In contrast to this, the gearunit must be taken out of operation to clean the coarse filter orline filter.With size 13 or larger, dual changeover filters are provided asthe standard because they can be "manually" switched duringoperation when they become dirty.If the availability does not play a role, a single line filter can alsobe provided here.