How to Select the Right Type of Wire Pulley
Pulleys make up some of the most crucial and reliable mechanical gears used in several motion devices and instruments. Pulleys typically guide a cable’s motion while reducing the amount of work needed to lift or move a given load.
Many manufacturers make wire pulleys from various materials, including industrial plastics or steel. Aside from the materials used to make the pulleys, manufacturers also tend to consider the pulley’s diameter when choosing the right pulley for a specific application.
If you are in the market for a wire pulley and can’t decide which one to get, the following guide is meant to make your decision a little easy. Read on.
Size of the Pulley
Depending on the pulley’s application, the size plays a significant role in influencing the type of wire pulley you should get. A pulley with a large diameter is more efficient than one with a small diameter. For each application, the specifications of the wire pulley are primarily based on the cable’s size and construction.
Mechanical cables are typically made using several strands wired around each other. Therefore, the diameter of the cable and its construction govern the pulley’s size and appropriate application.
Tradeoffs
Although a pulley with a large diameter is more efficient, it has increased costs, weight, and bulk compared to one with a smaller diameter. The main tradeoff that happens with pulleys is usually that small pulleys wear out cables much faster.
On the other hand, large pulleys are not suited for most applications. Using a pulley that is bigger than the required size is mainly disadvantageous when it comes to the costs involved. This, therefore, means that designers need to use a pulley that will fit a particular application.
Using a large size pulley for most applications typically implies that most pulleys available are small for the jobs they are used in. Many times, designers and manufacturers don’t allow enough space for selecting appropriately sized pulleys, which in the long run, limits the cable’s life span.
Lubrication
If you find that you’ve been using a small pulley for the wrong application, you can extend the cable’s lifespan by lubricating it. At Carl Stahl Sava Industries, we ensure that all of our commercial cables measuring less than 2mms in diameter are lubricated.
By lubricating our cables, we ensure that you get about twice or thrice the life of an otherwise single lifespan cable if the pulley is small. Another item worth noting is that all cables that are made to military specification standards are usually heavily lubricated.
If possible, choosing wire pulley and cables should include avoiding metal to metal contact. Too often such combinations result in premature cable malfunction due to abrasions. Coated cables are suitable where metal pulleys are involved while bare cables are suited for plastic pulleys.
Speed of the Pulley
Pulleys offer a mechanical advantage by transferring force from one shaft to the next. In a situation where there are two pulleys involved, the difference between the two wheels can be calculated using a pulley calculation formula.
The pulley ratio is derived by dividing the diameter of the driver pulley with the diameter of the pulley being driven. After finding the velocity ratio of the pulleys, you can use it to calculate the pulley speed. The pulley speed formula is found by dividing the drive speed of each pulley by their individual ratios and is typically measured using RPMs.
The pulley speed formula also comes in handy when one wants to learn how to determine pulley size for electric motor.
Get In Touch With Us
If you’re looking for high quality wire pulleys, you can browse Sava’s catalog of cables, fittings and tools. Our sales and engineering expertise give us an edge and allows us to meet your cable needs any time. Contact us today.