| 摘要 |
A keyboard instrument support has a driving device to control upward and downward movement of inner tubes relative to the outer tubes and a ratchet device to retain the elevation of the inner tubes. The ratchet device is composed of a ratchet alternatively rotated by the driving device and a leverage to abut a ratchet tooth such that after the inner tubes are elevated by the driving device, the abutment of the leverage to the ratchet retains the elevation of the inner tubes.
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