I have one. I also have a 3 blade fixed pprop which necessitates it’s use. Mine is held off when trans engaged. Applied when in neutral. A return spring assists in pulling the pads off the disc rotor. What do you need to know. Is this like yours?
I removed mine years ago. As I recall, there’s a hydraulic line that goes to an oil pressure fitting on the engine. When the engine is running and builds up oil pressure, it pushes a slave cylinder on the brake to disengage the brake caliper. The brake disc goes on the transmission output coupler and the caliper mounts to the transmission face. Maybe someone else has photos of the installation to share.
Pads wear and may need replacement. There’s a thread elsewhere on this site with info on ordering replacement pads.