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.

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.

Abstract: A device for applying tension to yarn or the like, the device including a stator and a rotor. The rotor includes an outer spool around which, in use, yarn or the like is passed and an inner part including a cylindrical sleeve-like portion. The stator includes outer pole piece defining apparatus extending between the outer spool and the sleeve-like portion of the inner rotor part, inner pole piece defining apparatus surrounded by the sleeve-like portion of the inner rotor part and apparatus for producing a magnetic flux between the inner and outer pole piece defining apparatus.