Lightweight aluminum 84' basket gin pole proves to be ideal for stacking large structures
Special stacking situations oftentimes call for unique rigging requirements for gin poles, especially when the erector is installing a large face self supporting structure such as this 340' tower with a 50' base that Great Plains Towers of West Fargo, ND, erected using a 24" square by 84' long basket gin pole.
According to the company's president, Kevin Reski, the Bismarck, ND installation required the use of a gin pole since no cranes were available. If they were obtainable, it would not have been an economical build since the structure had back to back angles and the equipment charges would have been exorbitant for the 15 days that might have been necessary for the crane to be on site.
Although most erection companies' gin pole racks will see an assortment of steel poles, Reski complements his installation capabilities with an aluminum gin pole that is designed from high tensile T6 aluminum. It is one of perhaps six in the nation that is used to construct communications structures. One of its distinct advantages is that it can be easily transported since a 20' section only waits 180 pounds. It is engineered to lift 5000 pounds vertically with a 5to1 safety factor.
The pole will bend out about twice as much as a steel pole and will still safely work within its rated design loading, Reski says.
His crew will lean the pole to almost 45 degrees to lift the panels and legs off the ground, up to the existing highest elevation. Then using two of the five-part rope "spider lines", the men will pull the pole back to an upright position so it its rooster head is plumb over the bolt up location.
One man on the ground, standing directly under the pole, will run the three or four spider lines by himself to pull the ropes in or let them out by allowing the rope to slide through his hands. This will boom the pole back and forth and left or right.
The boomer must tend 750' of 3/4" polypropylene rope in each of the spider line barrels. The spider ropes are each five part, so the ground man has lots of power and control even when the pole has thousands of pounds of weight on the load line. A spreader bar/lifting beam is sometimes necessary to keep 30' to 60' wide panels from collapsing when lifting from side tag pressure.
The jump line runs from the hoist to a base/foot block, up inside the tower to a block on leg #1, then down from the base of the pole through another block, then up to leg #2 through a block, then down to the base of pole to another block , then back up to leg #3 to deadhead there. If a four-legged tower is being constructed it would route through another block and back down another block at the base of the pole and up to leg #4 to deadhead.
This allows the "floating basket pole" to hang/float dead center in super wide towers, enabling more acceptable horizontal reach in all 360 degrees. Reski's crew uses 20' to 30' long steel chokers to support the weight of the pole from all tower legs.
See gin poles for additional information.
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