Telescopic elevator devices in particular for dollies

Claim 1

A telescopic elevator device in particular for dollies for cinema or television, characterized in that it comprises, in combination, a wheel mounted base member, a first extension member telescopically slidable on said base, a second extension member telescopically mounted at the interior of the first extension member, and means for controlling simultaneous sliding of said extension members with respect to the base with a differential speed such that the sliding speed of the second extension member is the double of the sliding speed of the first extension member, said means for the sliding with differential speed comprising a chain transmission, passing over two sprockets fastened to the first extension member and having their rotation centers aligned on a straight line parallel to the axis of sliding of said extension members, the two rectilinear portions of said chain transmission being respectively connected with the upper end of the base member and with the lower end of said second extension member, the simultaneous sliding of the two telescopic extension members being controlled by a hydraulic ram operating on a tubular member concentric and coaxial with said extension members and said tubular members having at the base a flange rigidly connected with a base of said first extension member, said base and extension members being of triangular cross-sectional configuration.