having additional brushes spaced intermediately of the main brushes on the commutator, e.g. cross-field machines, metadynes, amplidynes or other armature-reaction excited machines

Full Title

DC commutator motors or generators having mechanical commutator; Universal AC/DC commutator motors > characterised by arrangement for exciting > having additional brushes spaced intermediately of the main brushes on the commutator, e.g. cross-field machines, metadynes, amplidynes or other armature-reaction excited machines