How are the two circuits organised in the m3w?

On my ecomobile there are two disks at the front. One of them is part of the cbs and the other is the second circuit.
I needed it one time going down Oberslazberg because of boiling fluid.
Not a fun feeling but the second circuit worked fine - 🤯


1973 2CV AK400 Ralley
1985 plus 4 four seater
1992 Peraves ecomobil
bicycles (pedersen to recumbent)