| 摘要 |
The legs of a tripod are held in a selected adjusted position by three equi-spaced arms 14 mounted on a central hub 13 for swinging between extended and folded positions. Rack gears 22 on a shaft 20, mounted for linear movement along the hub axis 16, drive gear segments 19 on the inner ends of the arms whereby movement of the arms is co-ordinated so that they remain in the same relationship to the hub throughout their movement range. The upper end of the shaft bears a wide thread 25 engaged with inner tooth 27 of an annular plate 26 encircling the shaft whereby linear movement of the shaft causes plate 27 to rotate. A further annular plate 30, also mounted for linear movement along the hub axis, but fixed against rotation, can be (dis)engaged from/with the plate 26 by way of push button 50 so as to allow/prevent its rotation, thus freeing movement of the arms 14 or locking them in a desired position. |
