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A pulley sheave is pronounced "shiv" and often is confused with the pulley itself. This simple mechanical wheel has been utilized for centuries as a lifting aid. The modern version of this wheel comes in a variety of metals, and each is used for different purposes. Deciding what sheave is appropriate takes a little figuring, but it can be used in a variety of industries.
A pulley sheave is part of the pulley mechanism and is not the pulley itself. A pulley is a series of housings and wheels that allow rope, metal or chains to pass through to aid in lifting heavy objects. The sheave is simply one of the wheels within that housing. This wheel comes in a variety of sizes and materials, most commonly cast iron, steel or machined steel.
A cast iron pulley sheave is one of the most common types of wheel found in a pulley system. This material is famous for its strength and has been measured as being able to withstand 30,000 to 65,000 pounds (13,607 to 29,483 kilograms) of tensile strength. Cast iron pulley sheaves also are known for being able to withstand massive side loads. These types of pulley sheaves also are known for reducing belt slippage in order to increase speed and power.
A steel pulley sheave is coveted in industries where strict weight limits are in place, such as on boats. The reason for this unique benefit is because steel is much lighter than iron. However, a sheave pulley block forged from steel cannot handle as much weight and stress as an iron sheave.
Machine steel pulley sheaves are popular with industries that demand strong communication between workers. This stamped metal wheel provides a combination of strength and silence when it is in operation. This material makes it possible for silent operation when verbal commands are most important.
A pulley sheave has many specifications that can be customized for a particular job. Based on these factors, it can be used in a variety of industries. Users must consider how frequently the sheaves will be used, as well as what the weight load will be. Sheave height and width also are considerations that directly influence performance, because smaller wheels operate faster but usually cannot carry the same load. The pulling radius, cable diameter and maximum tension for the cable are other considerations that go into choosing the perfect sheave for a job.