Many mechanical devices use pulleys to transfer power from one component to another. Pulleys are wheels that are usually mounted to an axle that turns, thereby turning the pulley. Some companies or individuals may choose to make their own pulleys from pulley stock, which is essentially a long bar that can be cut to create pulleys. Pulley stock will usually already be machined with teeth or gears, since this requires special machinery, though the company or individual will still be able to cut the stock to the appropriate length.
The pulley stock material can vary depending on the intended application of the material. In most cases, the stock will be made from some sort of metal. Steel is the most common choice because certain grades of steel are exceptionally strong and resistant to heat damage. Some steel is even resistant to water damage. This, of course, means that cutting the pulley stock accurately can be difficult. This process is usually done using machinery that can be programmed to make precision cuts to specific tolerances. Computer numeric control (CNC) machines such as laser cutters or saws can be used to accomplish this task.
Some of the most common applications for pulley stock include building prototype machines or replacing an existing pulley with one of a custom size. Customized machinery may also require pulley stock. When developing prototype machines for any application, a designer is likely to require pulleys of differing sizes, either to find the size that works the best for the intended application, or to create a pulley size that is not a standard industry size. Using this stock usually requires a professional who can assess the needs of the machine and operate other machinery that can correctly cut the stock into the needed size.
The term "pulley stock" can also refer to the frame that holds a pulley in place. In some instances, a pulley system will feature several pulleys that need to be mounted next to each other. If this is the case, the pulleys will be mounted within a slotted frame known as a stock. Some of these stocks are made from steel and are used in heavy-duty settings such as on construction sites. Others may be made from wood or plastic and are used for lighter-duty applications, or even for nautical applications.