Abstract: Outer plates have a doughnut-like disk shape and are attached to the inner circumferential surface of a case member. On the other hand, inner plates have a substantially arc shape and are swingably supported about a position at a distance from the center of rotation of a shaft. The inner plates are held at a first position, at which the interlocking area between the outer plates and the inner plates is small, by a tension coil spring when the relative rotational speed between the case member and the shaft is small, and, when the relative rotational speed between the case member and the shaft exceeds a predetermined value are pivotally moved toward the outer plates by the shearing force of a viscous fluid and held at a second position at which the interlocking area between the movable plates and the first plates is large.

Abstract: Outer plates have a doughnut-like disk shape and are attached to the inner circumferential surface of a case member. On the other hand, inner plates have a substantially arc shape and are swingably supported about a position at a distance from the center of rotation of a shaft. The inner plates are held at a first position, at which the interlocking area between the outer plates and the inner plates is small, by a tension coil spring when the relative rotational speed between the case member and the shaft is small, and, when the relative rotational speed between the case member and the shaft exceeds a predetermined value are pivotally moved toward the outer plates by the shearing force of a viscous fluid and held at a second position at which the interlocking area between the movable plates and the first plates is large.

Abstract: There is provided an improved rack for feeding photosensitive materials, which is so adapted that an operator can turn its feed rollers without soiling his hand. A vertically-extending roller driving shaft is rotatably provided outside of a rack body. A sprocket carries a bevel gear which is coaxial with the sprocket and meshes with a bevel gear fixed to the top end of the roller driving shaft. The bevel gear mounted on the sprocket has a cylindrical member. Outside of the cylindrical member is provided a knob. A spring is mounted to bias the knob away from the sprocket. The knob has a control sleeve which can be moved to a position where it surrounds the sprocket. After moving the control sleeve to this position, the knob is turned by hand to turn the roller driving shaft.