Patent ID: 6073903
Filing Date: 2000-06-13
Classification: F16M

Abstract:
A telescopically extendable column for a camera support platform having a plurality of interconnected stages, wherein the column is triangular in cross-section, the column comprising:an extendable gas powered strut providing a force which varies with extension of the strut from a maximum force when the strut is fully retracted to a minimum force when the strut is fully extended;first, second and third means for transmitting the force provided by the strut directly to a first one of the stages with a mechanical advantage which increases with extension of the strut and reduces with retraction of the strut to compensate for the variation in the force provided by the strut during extension and retraction of the strut to apply a substantially constant force to the first stage throughout the range of extension and retraction of the strut, each of the first, second and third force transmitting means being disposed on a respective side of the column between the first stage and a second one of the stages, each of the first, second and third force transmitting means comprising:a drive wheel mounted for movement with the strut, a distance between an axis of rotation of each of the drive wheels and a periphery thereof varying around a perimeter of the drive wheel;a flexible driving element extending around a part of the periphery of the corresponding drive wheel; anda positive driving connection between each of the flexible driving elements and the corresponding drive wheel, a first end of each flexible driving element being connected to a corresponding separate anchorage spaced from the corresponding drive wheel and a second end thereof applying a force to the second stage to transmit movement thereto in response to movement of the first stage, each of the drive wheels turning through up to approximately half a turn over the range of extension of the strut.