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In the construction of tall concrete towers, a two part derrick is suspended by cables from the tower to the lower part of the derrick. The derrick is extended on hydraulic rams, raising its upper part and outside casting forms. A pulley system maintains a deck scaffold and inside forms at their ori

In the construction of tall concrete towers, a two part derrick is suspended by cables from the tower to the lower part of the derrick. The derrick is extended on hydraulic rams, raising its upper part and outside casting forms. A pulley system maintains a deck scaffold and inside forms at their original level during extension. Extension of the derrick slakens cables from the tower to the upper part of the derrick. These cables are disconnected from the tower and reconnected at a higher level. Outside forms are fixed, reinforcing steel set in place, and the derrick retracted, raising the deck scaffold and inside forms by the pulley system, and slacking the lower cables. The lower cables are disconnected from the tower and reconnected at a higher level. Inside forms are set and concrete is poured. The concrete sets and the procedure is repeated. The deck scaffold comprises radiating wooden beams with endpieces. As tower diameter decreases due to taper at higher elevations, the endpieces are removed, the beams cut back, and the endpieces replaced on the new beam ends.

대표청구항 ▼

A derrick for use in the construction of a tower, which derrick may be suspended from the tower by cable means, the derrick having: an upper part and a lower part, one of which may be vertically extended relative to the other to vary the vertical dimension of the derrick; pulley means for automatica

A derrick for use in the construction of a tower, which derrick may be suspended from the tower by cable means, the derrick having: an upper part and a lower part, one of which may be vertically extended relative to the other to vary the vertical dimension of the derrick; pulley means for automatically maintaining an item which is suspended from the derrick at a constant elevation when the derrick is extended, and for raising the item when the derrick is retracted, said pulley means comprising: cable means attached to the item; at least one first pulley suspended from a relatively high point on the upper part of the derrick through which the cable means suspends the item from the derrick and through which the cable means is turned downwards; a post attached to a bottom of the upper part of the derrick and extending down past the bottom of the upper part and past a top of the lower part of the derrick; a second pulley on a lower part of the post which turns the cable means form the pulley toward the top of the lower part of the derrick; and an attachment point at the top of the lower part of the derrick to which the cable means is attached.