| 摘要 |
A roller system includes a frame, an upper roller assembly, a lower roller assembly and an actuator. In one embodiment, the upper roller assembly includes a first rotatably supported cylindrical member. The lower roller assembly is movably supported by the frame below the upper roller assembly and includes a second rotatably supported cylindrical member. The actuator is configured to move the second cylindrical member between an elevated position and a lowered position. In another embodiment, the roller system includes a frame, at least one upper track, an upper roller assembly, at least one lower track and a lower roller assembly. The upper roller assembly includes a first rotatably supported cylindrical member extending along an upper axis. The upper roller assembly is supported by the upper track and moves along the upper axis between an operation position and a removed position. The lower roller assembly includes a second rotatably supported cylindrical member extending along a lower axis. The lower roller assembly is movably supported by the at least one lower track and moves along the lower axis between an operation position and a removed position.
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