The Harrington chain hoist is a mechanical device that consists of carabiner style hooks, gears, and a loop of chain used in raising or lowering heavy objects. While little is known about who was the first to come up with the idea of using mechanical advantage machines to lift heavy objects, there are accounts of a pulley system being used in lifting or pulling objects in Ancient Greece.
Types of Chain Hoists
There are three main types of chain hoists in use today: air powered, manual and electric. Manually powered systems and air systems are generally used in lower weight work while industrial electric styles of chain hoists will be used for higher weight jobs. In the case of the manual chain hoist, the loop that is pulled on to work the hoist is most often a metal chain but can be made from rope or other fiber.
Chain Hoist Gearing
Chain hoists contain gearing mechanisms that strategically reduce the amount of physical labor required to lift the object. The gearing systems make use of the concept of mechanical advantage, causing a low force, high travel input to be translated into a high force, low travel output of energy, allowing heavy objects to be lifted by simply pulling on a loop of chain.
The time spent raising or lowering the load is elongated reducing the amount of power that is needed. For working long hours in theatrical productions this tool will greatly increase productivity. Many models also include a ratcheted wheel that, when engaged, prevents the load from slipping or falling. This wheel can be disengaged, and the main gear turned backwards for lowering a load.
The Harrington chain hoist is often used in industrial disciplines such as construction and manufacturing. However, they can also be used in an Auditorium or a Black Box Theater to raise or lower set pieces, speaker arrays or other heavy loads. Chain hoists can also be used to do the work often done by a Fly system (if speed is not an important factor) because chain hoists are much slower carrying out the task.
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