| 摘要 |
The system has a carrier frame (1) equipped with rollers (9), where the rollers rotate around a middle point. The rollers are arranged approximately in middle of side edges of the carrier frame. Another carrier frame comprises centering elements and spacer elements (3-5). Shields are arranged at the former carrier frame for covering the rollers. The centering elements comprise a partly rotating collar in a vertical direction of a carrier frame plane. The former and/or the latter carrier frame are equipped with lattice bottom or closed bottom. |
