From memory the discs in the later larger Ferguson tractors (165...

From memory the discs in the later larger Ferguson tractors (165 to 188) built from around 1973 to 1978 were multi plate oil immersed discs , I do not know how complicated they were being multi disc as they never broke down to need repairing for me to see how they were made.
They worked very well no squeaking and could pull up a 8 ton load also all mechanical linkage without the need for power assistance to foot pedal so indicates very efficient method of accuation
Yes conveyers have brakes ,
The Rover cars in the 70s use to have inboard disc brakes on the rear axle but were considered very unreliable guessing they were not oil immersed.