I don’t really follow those images.
in the Perlisten Subs, both Drivers excurse outwards, in phase with each other.
if I really try to interpret those images, you need “C:”
Red arrows in phase and both excursing outwards at the same time.
Just one toward the motor, and one away.
So, take “a” and reverse the direction of the arrows for “2” to reflect the actual motion of the Drivers.