Device for shifting one structure with respect to another

摘要

A device 10 for shifting one structure with respect to another is provided. The device 10 comprising: a body 12 defining a cylinder; a core 14 within the cylinder and rotatable in the cylinder with respect to the body 12; and a coil spring 74 connected between the body 12 and the core 14 and which is wound or unwound as the core is rotated in the cylinder. A compressible ring 48 is carried by one of the body 12 and the core 14 and in frictional contact with the other of the core and the body. Means 50, 60 for compressing the ring 48 is provided so that the frictional resistance offered by the ring 48 to turning of the core 14 in the cylinder 12 is increased.