Patent ID: 11156307

Abstract:
The present invention relates to a failsafe valve actuator (10) comprising a drive mechanism (12), a drive shaft (42) having a clutch (50) arranged adjacent to a threaded portion (44) of the drive shaft (42), and a clutch actuator (52) coupled to the clutch (50) and arranged to move the clutch (50) between an engaged position in which the clutch (50) engages with the threaded portion (44) of the drive shaft (42) and a disengaged position in which the clutch (50) is disengaged from the drive shaft (42). In response to energisation of the clutch actuator (52) the clutch (50) is moved to the engaged position such that threaded engagement between the drive shaft (42) and clutch (50) transfers rotational movement of the drive shaft (42) by the drive mechanism (12) into axial movement of the drive shaft (42) and holds the drive shaft (42) against a drive shaft bias member when the drive mechanism is inactive. Movement of the clutch (50) to the disengaged position, causes the drive (12) shaft bias member to automatically return the drive shaft (42) to the failsafe position.