| 摘要 |
Two pairs of retainer devices (14a, 14b) are located at opposite ends of the bed, the first pair (14a) being substantially parallel to the second pair (14b). Two upper press bars extend between one pair of retainer devices and two lower press bars extend between the other pair of retainer devices. Two tensile strut devices extend through one pair of retainer devices and are arranged symmetrically relative to the lower press bars. A reinforcing device with four crack preventing devices (30, 40) are arranged around the upper and lower press bars. |
