a selectable one - way clutch assembly uses hydraulic - actuation to select operating modes within a rotating housing . two races of the sowc assembly can rotate at disparate speeds , i . e ., one race is not grounded prior to actuation . the sowc assembly has a pair of races keyed to different housings and hubs . the housing and hub can be attached to different elements of a gear train , for example , which can be rotating during the various gear states . a hydraulic actuator or multiple actuators can be keyed to the housing , with axial motion of the actuator or actuators selecting a state or operating mode of the sowc assembly . the actuator has axially - extending tabs that engage radially - extending fingers of the selector plate , thus rotating the selector plate in different directions when applied or released . multiple actuators can be used in conjunction with multiple selector plates to provide additional sowc operating modes .