| 摘要 |
<p>A manually repositionable support arm (20) mountable on a support structure (22) for movement of a keyboard tray (30) between a plurality of work positions is disclosed. The device comprises a mounting frame, a first roller member (50) that is rigidly mounted on the mounting frame in fixed relation thereto, and a second roller member (60) that is rigidly mounted on a depending portion of the keyboard tray in fixed relation thereto. A rigid housing (70) substantially encases the first and second roller members in journalled relation about respective first and second circumferential bearing surfaces on the first and second roller members so as to hold the first and second roller members in fixed spaced relation to one another and so as to permit relative rotation of the housing with respect to the first and second roller members. A constant length closed-loop band (80) is operatively mounted around both of the first and second roller members in fixed indexed engagement therewith so as to surroundingly link the first and second rollers members for planetary movement of the second roller member about the first roller member within the rigid housing, such that the second roller member remains substantially rotationally aligned with respect to the first roller member. A lock is operatively mounted between the second roller member and the rigid housing member to selectively preclude the relative rotation of the second roller member with respect to the rigid housing, which, in turn, selectively locks the keyboard tray in any one of said plurality of work positions.</p> |
