A used pulley can be the solution to a great variety of problems regarding mechanical devices such as hoists, come-alongs, and motorized vehicles, but it is important to make sure you know what you are looking for. Before you start your search for a used pulley, decide how the unit will be used and find out what types of pulleys are appropriate for such purposes. A pulley used in a vehicle's engine, for example, must be a certain size and shape, and it may even be made to certain manufacturer's specifications.
The function of a used pulley can vary, so the criteria for choosing the best one can vary as well. Light pulley systems may feature plastic wheels and lightweight aluminum axles, while heavier-duty systems may feature steel pulleys with steel axles and other components. The materials will only be appropriate for certain applications, so be sure the used pulley you are considering is right for the job it will perform. Engine pulleys must be made of heat-resistant steel, for example, and they must be designed for use with that specific engine. A hoist system may require the use of a pulley of a certain shape or size; other pulleys will not work properly with the system.
Once you have determined what type of used pulley you need, you will have to do a visual inspection of the components to ensure they are all in working condition or can be fixed to a working condition. The wheel itself should not be cracked, deformed, warped, or otherwise damaged. If the wheel is steel, some rust may be present. This does not necessarily mean the pulley is not usable, but if too much rust is present, or if the rust is so thorough that holes have formed, the pulley is no longer usable and should be disposed of. Bearings are sometimes mounted between the wheel and axle; these bearings should rotate smoothly and freely with no grit, catch points, or slowness.
All other components of the used pulley system will also need to be inspected. Motorized pulleys should be tested thoroughly, and any cables or chains will need to be inspected for burrs, breaks, rust, or other damage that may indicate a potential failure of the unit. Remember that electronic units may not exhibit any outward signs of wear, though they may malfunction down the road. Even a thorough test of the unit may not reveal problems, so whenever possible, get a warranty or return policy spelled out clearly for you before purchasing.