| 摘要 |
PURPOSE:To reduce the number and weight of spring boards by interposing slidable friction plates between adjacent spring boards to increase frictional force between the boards. CONSTITUTION:Between adjacent spring boards (1, 2) (2, 3) are interposed friction plates 7 which have relatively high frictional resistance to the spring boards 1-3 without substantial spring property and is formed of steel sheet, for example, to have antiwear property. Thus the number of adjacent slidable surfaces of the spring boards 1-3 during bending operation is 4 so that the frictonal force between the boards can be sufficiently enlarged. |
