Choosing a small pulley does not have to be a difficult process, but you will need to determine early on how the pulley will be used to ensure the proper size and weight capacity is purchased. Pulleys come in a variety of sizes and can be made from various materials, including metal, nylon, and even wood, and the materials will have a significant impact not only on how long the small pulley lasts, but also for what applications it can be used. Some pulleys have specific intended purposes; an engine pulley, for example, is used in an automobile engine and may be designed for a specific brand or design of engine.
The best way to find the correct small pulley for an engine is to consult an owner's manual, manufacturer, or parts distributor. Any of these resources should be able to give you an idea of which small pulley is appropriate for the intended application. Using a pulley that is not designed for a particular engine may lead to failure of the engine or damage to other engine components. Almost all engine pulleys are made from metal, and steel is usually the metal of choice because it can be exceptionally resistant to heat damage as well as damage from impacts.
Other small pulleys can be made from plastic or nylon. These small pulley models are usually used for exceptionally light-duty applications, such as hoist systems designed to hold canoes, kayaks, or bicycles in a storage space. Sometimes larger nylon pulleys are designed to hold more weight, and they can be used in nautical applications on sailing vessels. Nylon can be resistant to wear and damage such as cracking, but the weight capacity of such a small pulley is likely to be lower than that of a metal pulley.
Some pulleys feature grooves worked into the outside of the wheel. Such grooves are designed to ensure a rope or cable stays in place around the perimeter of the wheel. Other pulleys are flat around the outside to accept belts. It is important to choose the correct style of wheel, as a grooved wheel can damage a belt and vice versa. Some specially designed pulleys may feature teeth to work with chains or belts for greater traction and power when the pulley system is in use. The number of pulley wheels in the system will also dictate how much weight can be pulled or lifted, so the user will need to analyze how much weight needs to be lifted in accordance with how many pulleys exist in the system.