While all cranes, like one from Wazee Crane, must have the ability to safety handle a load that is at least 125% of the crane's rated capacity, the overhead crane's capacity and ability is largely dependent on its entire structure, which includes the wiring used as well. Most overhead cranes use 6 x 19 class wire ropes that contain 6 strands of wiring with a nominal 19 main wires in each strand.
Generally speaking, small wires are recommended for situations where flexibility is crucial whereas large wires are recommended when the cable will likely be rubbed or dragged through abrasives. Regardless, all wiring used by overhead cranes should be properly lubricated at all times for optimal performance and efficiency.
Principal Functions Achieved Through Lubrication
By ensuring the wires are well-lubricated at all times, you can prolong the lifespan of the overhead cranes, reduce the amount of repairs that may be needed in each given year, and also improve the overall capacity of the cranes. The lubrication is used to serve to principal functions:
- reduce friction placed on each individual strand of wire, as it rubs against each other and as it rubs against its surrounding environment.
- protect the wiring from being corroded, as the lubrication will coat both the exterior and interior surface of the wiring to ensure that corrosive materials do not make direct contact with the wires.
Two Main Categories of Lubrication Used
Generally speaking, the lubricants involved can be separated into two distinct categories — ones that penetrate and ones that coat.
Lubricants that are designed to penetrate generally contain petroleum solvents. These solvents are responsible for ensuring that the lubricants reach the core of the wiring before evaporating and leaving behind a thick film overtop each individual strand. Each wiring is then protected as a result.
On the other hand lubricants designed to coat the wiring will not penetrate inside the wiring, but will rather coat the outside of the cable to prevent moisture loss and to reduce the amount of wear that the wiring will experience from friction and corrosion.
While you could use either one of these lubricants, experts now recommend using both. This is because most wires generally fail from the inside, so it is important that these areas receive sufficient lubrication as well. By using a combination approach, you will be able to ensure that the wiring is protected from all angles, which can help prolong its overall lifespan and durability.
Pros and Cons of the Different Types of Lubricants
There are 5 different types of lubricants available on the market: petrolatum, asphaltic, petroleum oils, grease or vegetable oils. All of which possess unique properties that make them more advantageous than other options.
Lubricants made from petroleum tend to offer excellent corrosion and water resistance. In addition, since the lubricants are translucent in nature, they make it easy for technicians to inspect the wiring in order to make sure that there are no damages present. Although these lubricants are able to offer excellent protection, their consistency only holds well in cold temperatures, and not so much in hot temperatures. In fact, in hot temperatures, the lubricant has a tendency of dripping off.
Asphaltic lubricants are great for those who will be keeping the wiring in storage for prolonged periods of time. Although asphaltic lubricants can handle hot climates, they become brittle in cold climates. These lubricants also darken when they dry, which can help conceal flaws and damages in the wiring.
There are various lubricants made from greases like sodium, lithium and aluminum complex soaps. These lubricants are not as highly recommended because they do not penetrate into the core. On the other hand, petroleum and vegetable oil based lubricants are easy to apply, and are extremely effective in penetrating into the core. These lubricants are also quite fluid in nature, and can be washed off the wiring easily.
While the wiring used for overhead cranes will be initially lubricated when they are manufactured, it is your responsibility to make sure that the wiring is re-lubricated regularly in order to preserve its overall function and to prolong its lifespan. If the lubricant has dried off, you will need to wash it off before applying another layer. Understanding the fundamentals of lubricating the wiring can also help improve the overall capacity and capabilities of the overhead cranes.