| 摘要 |
<p>The movable supporting arm (14) is mounted on a pivot pin (44) at its inner end on a wall or base. The outer end is spring counter-balanced by an adjustable spring and there is a friction brake which controls movement and locks the arm in position. The friction brake and arm can both be mounted with the same hand so that the supporting arm can be moved into position and locked in position.</p> |
