This is a two-brush dynamo with a soft iron core

The photo in your PDF sure looked like it had 3 brushes. Sorry.

 

Yep - it's hard to see the brushes - the dynamo has integrated ignition (points/conderser) atop the commutator. The D+, DF, and D- junctions make it look like three brushes.

 

The D+, DF, and D- junctions make it look like three brushes.

Yeah, usually DF is a third brush and they sometimes were movable to adjust the output.

 

Hi, I own an MZ with that model Dynamo. Its a two brush, 'bosch-style minus regulated' 6volt 60Watt (transient max 90Watt).
The 4.4 ohm resistor between D+ and the field coil earth point works in conjunction with the regulator (which you don't have fitted) and provides the field coil with power when the 'vibrating' regulator points (not the big reverse voltage cutout points) are hovering in between 'power-to-field' and 'earth'. Your wiring diagram shows the battery being used to power the field coil, which means that as the revs increase above about 2000rpm, the dynamo will output around 6.3 volts, thereafter ever-increasing voltage... i.e. its unregulated....
A company in the Czech Republic called Vape make a solid-state regulator designed for this dynamo (model R81)
Search also 'Lothar MZ electrics' or use this link for a really good handbook https://pic.mz-forum.com/lothar/Elektrik-en/MZ-Elektrik.htm

 

CORRECTION - Dynamo. Its a two brush, 'bosch-style Positive regulated' 6 volt 60Watt (transient max 90Watt), supplying a negative Earth wiring setup.
.....(sorry about that, got my negative earth wiring mixed up with my dynamo regulation method)....