PURPOSE:To obtain the device with no liquid leakage and with excellent durability by a structure wherein one magnetic member slidably housed within a sealed cylinder with liquid therewithin while the other magnetic member, which magnetically coupled with said magnetic member, is slidably provided outside the cylinder. CONSTITUTION:The viscous fluid 2 such as silicon oil or the like is poured in the cylinder 1 bottomed at one end and the cylindrical primary magnet 3, which is axially magnetized, is slidably housed in the cylinder 1 and, after that, the other end of the cylinder 1 is sealed with a stopper 4. In addition, a bottomed cylindrical outer tube 5, at the open end of which a cylindrical secondary magnet 6 magnetized so as to magnetically couple with said magnet 3 is mounted, is slidably fitted onto the outer peripheral part of the cylinder 1. Owing to the structure as described above, when the outer tube 5 is moved toward the direction of A, the magnet 3 is moved toward the same direction being followed by the magnet 6. During the movement, the magnet 3 is applied with the viscous resistance due to the fluid 2, resulting in time-lagg of the outer tube 5.
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