Air Hoists and How Do They Work?September 4, 2015
Hoists enable easier lifting and maneuvering of items to streamline strenuous industrial applications and constantly working processes. A hoist is a cable wrapped around a wheel that mechanically lowers / transports items. Hoists are used to lift otherwise disabled individuals as well as in industry and transportation / construction environments. Hoists are designated for specific purposes according to their type of cable and power source.
Working Air / Pneumatic Hoists
Air, or pneumatic, hoists use an attached up-and-down control pendant similar to standard hoist systems, with the added floating functionality supplied by the compressed air that powers it. A weightless vertical movement is facilitated by the floating air function.
Air hoists can be operated in remote environments because they do not run on electric motors. Air hoists typically weigh 40% - 50% less than electric hoists. They are designed to be low maintenance, impervious to dirt and dust, heat, vapors, high temps, and humidity, and self-cooling. Air hoists are well-suited for chemical plants, paint shops, and mines. Drawbacks of air hoists are their difficult position and speed control.
Operating The Air Hoist
Air hoists should only be operated by fully-trained authorized operators. They are intended to lift or support materials and products, not to lift or transport personnel. The hoist should have required safety features such as load brakes, emergency stop and shock protection, and hook latch and limit switch. The operator should always wear suitable safety gloves to insulate between hands and metal hand controls. Outdoor stationary hoists should be protected from the weather and regularly maintained. Daily checks of the air hoist braking function, emergency stop, and lifting / lowering limits should be performed. Chains should be checked and lubed monthly. Compressed air connections, motor, all bolt and pin connections, sprocket wheel and chain guides, load hook, brake (with load), and chain box should be annually inspected.
To avoid underperformance or overloading, the air hoist is operated at a 4 or 6 bar system pressure. The air supply must be clean and dry for the air hoist to operate properly and they should never be operated with other gases. Never use an air hoist in nuclear plant (critical areas) or where organic acids are present, over acid baths, or in plants containing corrosive materials.
Types of Air Hoists
Air-balanced hoists also serve as balancing devices, which allows them to supporting heavy loads or the primary weight while the operator moves the item into position for assembly. The floating feature provides control of awkward or fragile materials or products that must be precisely positioned.
Air-powered wire rope hoists typically have faster lifting speeds than chain hoists. Although wire rope air hoists tend to be more expensive, sparking and static / electrical hazards are minimized. Loads in hazardous environments can be safely lifted. Hoist and trolley air motors reduce electric motor dangers. Stainless steel wire rope, bronze bottom block and hook, rubber bumpers and copper-beryllium trolley wheels reduce sparking in dusty environments.
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