PURPOSE: To make it possible to remote-control the resetting action of a damper mechanism and open and close the damper mechanism only with the action of fuse by providing a holding tube with a cam member which changes over a lock pin into release state when the state of engagement of the latching member for a fuse is released.
CONSTITUTION: When a cylinder 36 is set to exhaust state, an outer shaft 25 and a middle shaft 23 rotate together by means of a lock pin 26 which is pushed by the force of a first spring 50. When a cylinder rod 37 is pushed back and the state of engagement between a fuse 42 and a latch member 31 is released from the state in which a damper mechanism is open, the latch member 31 rotates clockwise along with a holding pipe 30 by means of the force of a twist coil spring 40. Then a cam member 32 provided on the holding pipe 30 kicks out to the outside a kicking piece 29 against the force from a spring 28, making a middle shaft 23 freely rotatable relative to an outer shaft 25. At this time the end section of a second spring 45 which engages with a latch piece 46 becomes a fixed end and the middle shaft 23 rotates counterclockwise by the force of a second spring 45.