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Diagram 3 shows three rope parts supporting the load W, which means the tension in the rope is W/3. Thus, the mechanical advantage is three-to-one. Thus, the mechanical advantage is three-to-one. By adding a pulley to the fixed block of a gun tackle the direction of the pulling force is reversed though the mechanical advantage remains the same ...
Spar tree at a logging camp in the United States, 1924. A spar tree is the tree used as the highest anchor point in a high lead cable logging setup. The spar tree is selected based on height, location and especially strength and lack of rot in order to withstand the weight and pressure required.
Early on, it was customary to trim and top a tree making it into a 'spar pole' or 'spar tree' for the purpose of supporting the head blocks but gradually the use of wooden spars gave way over the 20th century to the use of steel spars stood up for the purpose. In any event the spars are supported by a number of guy wires. [1]
The tree provides distributed mechanical support, reducing localised mechanical deflections, which in turn reduces optical distortion. [4] Unlike the applications described above, which are two-dimensional, the whippletrees in telescope mirror support cells are three-dimensional designs, [ 5 ] since the tree must support multiple points over an ...
The swing yarder has several drums to pull in the cables. The cables run up an angled boom and then to the far side of a setting. By using two cables set up like a clothes line, the rigging can be pulled out and logs can be pulled across a logging setting where the trees have been previously felled.
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A tree structure, tree diagram, or tree model is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree , although the chart is generally upside down compared to a biological tree, with the "stem" at the top and the "leaves" at the bottom.
A gin pole used to install a weather vane atop the 200-foot steeple of a church Roof trusses being assembled with gin poles. The gin pole is derived from a gyn, and considered a form of derrick, called a standing derrick or pole derrick, [2] distinguished from sheers (or shear legs) by having a single boom rather than a two-legged one.