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The NIOSH lifting equation is a tool (now application) that can be used by health and safety professionals to assess employees who are exposed to manual lifting or handling of materials. [7] The NIOSH lifting equation is a mathematical calculation which calculates the Recommended Weight Limit (RWL) using a series of tables, variables, and ...
Hoist atop an elevator. A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be manually operated, electrically or pneumatically driven and may use chain, fiber or wire rope as its lifting medium.
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. 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, Diagram 3a. This is an example of the Luff tackle.
This leads to a mechanical advantage: the force needed to lift a load is only a fraction of the load's weight. At the same time, the distance the load is lifted is smaller than the length of chain pulled by the same factor. This factor (the mechanical advantage MA) depends on the relative difference of the radii r and R of the connected pulleys:
A team of riggers design and install the lifting or rolling equipment needed to raise, roll, slide or lift objects such as heavy machinery, structural components, building materials, or large-scale fixtures with a crane, hoist or block and tackle. Rigging comes from rig, to set up or prepare.
Examples include the closing stone in a string course, cylindrical column drums, decorated column capitals, and coping stones in a pediment. Heavy ashlar stones are also bedded using a lewis. The lewis is liable to slip out of the seating if some of the weight of the stone is subtracted from the appliance, such as when the stone bumps on the ...
Establishing the lifting anchor positions will influence the rigging arrangements used and therefore the static analysis of the rigging should be determined. Particular rigging configurations may be more suitable for particular job sites or lifting in place considerations, and the lifting design should denote the assumptions accordingly.
To lift a load, a separate line runs up and over the mast with a hook on its free end, as with a crane. [ 1 ] [ 2 ] Derricks are especially useful for high-rise rigging, jobs that cover a long period of time, or jobs when the impact to street or pedestrian traffic is a concern. [ 3 ]
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