This can be achieved by planting gears on them (driven and leading) with a given center distance, which will rotate the shafts with disc blades. If necessary, change the blades will change and the center distance at the gears.
Put two gearboxes and two motors on the upper and lower shafts and move quietly. The speed itself will converge. You can put the worm gear and drive shaft diagonally on the common motor and splined connection for mobility.
Some movable adjusting link is also necessary to enter. You can do without the idler gears by moving one of the shafts. Given the small required amount of adjustment, the movement can be carried out with a conventional eccentric.