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Though it’s shape, size, and construction has changed countless times, its basic concept and function has always remained the same; by leveraging the power of its inputs the capstan can apply force to another component to move extremely heavy loads. |
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The anchor has always been a symbol of great force for the Navy; an immobile grounding instrument used to hold its mightiest vessels steadfast to the ocean floor. A symbol of both strength and power...but have you ever given thought as to what moves this indomitable force? It’s the capstan. Small by comparison, it’s this device that leverages power to raise the anchor from its deepest depths. The origin of the capstan dates back several hundred years to when the term was first used for a leveraging device on a ship. Early ship designers engineered capstans to be used to heave heavy rigging and to draw a ship alongside a pier when docking. The largest of these |
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capstans were used to lift a ship’s anchor, oftentimes in excess of 5 Tons. In pre-steam days, these capstans were manually operated by men pushing large poles fed into the sides of the device. As the men applied rotational force to the capstan, the leverage created enabled the great loads to be moved. The rope or chain would wind around the capstan one or more times, but would not be stored on the capstan itself. This important feature differentiated capstans from ordinary drum winches. On a capstan, the line pull and the line speed can remain constant, regardless of the cable length. As time went on, requirements for lighter, sturdier, and stronger capstans led to unique solutions combining special materials with new driving system concepts. Today’s modern capstans have astonishing weight to performance ratios, enabling them to achieve extremely high gear reductions, up to 1:1000, all with minimal backlash. The use of the capstan has grown significantly as well and has not been limited to the shipping industry. Early wine vineyards in Switzerland used the motorized devices for mechanizing the growing of grapes on the steep Swiss hillsides. Farmers used capstans to pull plowing tools through their fields. Small capstans can even be found in the mechanisms of tape recorders, where they apply force to the tape causing it to be drawn past the heads at a constant speed; such capstans are precision-machined spindles, with a very accurate surface profile. Capstans can essentially be found in almost all industries, to include public utilities, civil engineering, agriculture and the military. Some current common uses for larger capstans are for recovery of stalled or damaged vehicles (including tanks), moving rail cars on sidings, hauling logs and assisting the operations of "snowcats", used for maintaining steep ski areas.
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