| 摘要 |
The roller plate (1) has components (2,3,4,5) positioned at its periphery so that the roller plate locates securely on the base surface and rolls in relation to it. The plate has a hole (15) in its central part in which a component (16) is fixed and so shaped that the plate can execute a circular movement around a vertical axis through it. The rotation of the plate occurs with the aid of the peripheral components. |
