According to ISO 22153, a multi-turn gearbox is a gearbox which transmits torque to the valve for at least one revolution and needs to be capable of withstanding thrust and that can be manually operated by handwheel and/or automated with a multi-turn actuator.
Multi-turn gearboxes to increase the torque or to shift the output axis can be combined with SA ... multi-turn actuators and AUMA spur and bevel gearboxes. Of course, gearboxes can also be used in combination with manually operated valves.