| 摘要 |
<p>An upper part of a column can be pivotally lowered and raised relative to a lower part thereof for servicing of an appliance mounted thereon. However, before the column part can be lowered it must be raised through a limited vertical displacement relative to the column part. A releasable locking device is provided to hold the column part at the upper end of this displacement, and comprises configurated slots which receive a rotatable pivot shaft. Each slot has relatively wide portions and a relatively narrow portion and the shaft is so shaped that it can pass into the narrow portion (and thereby permit said limited vertical displacement of the column part) only when it occupies a predetermined angular orientation.</p> |
