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5 Interesting Things You Might Not Know About Wire Rope

Anyone looking for rigging supplies here on our website will find several varieties of wire rope to choose from. Wire rope is one of the primary materials for managing complicated lifts. It is preferred by experienced lift masters because of its strength and reliability.

As with most things in the Mytee inventory, there is more to wire rope than meets the eye. How it’s constructed, where it comes from, and many other aspects of wire rope remain hidden for the simple fact that there is really no need to know. We want to change that for our readers. To that end, there are five interesting things about wire rope you might not know, listed below.

1. It Was Preceded by Wrought Iron Chains

Before there was wire rope, lift masters and engineers relied on wrought iron chains to do the work. But as you might imagine, failure was a common problem with said chains. All it took was one bad link to create a disaster. So engineers had to find a replacement that was both up to the task and would greatly reduce the risk of catastrophic failure. They looked to the engineering of spiderwebs to eventually come up with the design we now know as wire rope.

2. A Helix Design Provides the Strength

One of the things engineers learned by studying spiderwebs is that a helix design offers incredible strength. The helix design starts with a single wire that acts as the core of the rope. Additional wires are then twisted around the core and fastened together. This design spreads the force of a load across multiple wires instead of a single link of chain.

3. The Helix Also Limits Failure

If there is one flaw to the helix design, it is the fact that the individual wires that make up a rope can wear out over time due to friction. But it is not a big deal for the most part. Why? Because individual wire strands rarely fail at the same time. Initial failure is generally limited to one, in which case the remaining wires are more than capable of carrying the load.

4. The First Wire Ropes Appeared in the 1830s

Historically speaking, the first wire ropes were manufactured to support mining operations in the 1830s. Lift masters in Germany used them to replace metal chains and hemp ropes. The first wire rope produced in the U.S. appeared in the early 1840s. Its purpose was to provide support for suspension bridges.

By the late 1840s wire rope was used heavily in the railroad industry for a variety of different purposes. That led to a number of manufacturing plants opening across United States producing wire rope in ever increasing volumes.

5. Wire Ropes Are Classified According to Use

Just like there is more than one way to construct a wire rope, said ropes are classified according to their use. There are four generally recognized classifications as follows:

1. Running Ropes – Stranded ropes used over sheaves and drums that will bend them.
2. Stationary Ropes – Spiral ropes capable of carrying fluctuating tensile forces.
3. Track Ropes – Fully locked ropes capable of handling the kinds of forces typical of crane lifting.
4. Wire Rope Slings – Stranded ropes used as harnesses for lifting.

So, how did you do? If you knew all five things mentioned in this post, you know more about wire rope than the average person. One last thing to know is that you can get the wire rope you need for your rigging jobs here at Mytee Products.


Safe Lifting Practices with Slings and Shackles

There are times when forklifts, pallets, and loading ramps are not sufficient for moving cargo around. That’s when you need slings and shackles. Lifting a load with slings and shackles also involves some sort of boom, be it from a boom truck or crane. Needless to say that there are a whole host of safety considerations when engaging in this sort of lifting operation.

The Occupational Safety and Health Administration (OSHA) has issued its own guidelines dealing with safe lifting practices. They mention a number of very specific things having to do with slings and shackles. For the benefit of our readers, we have summarized OSHA guidelines below. You can go to the OSHA website and search ‘safe lifting practices’ for more details.

Choosing the Right Kind of Sling

OSHA’s guidance begins with a discussion about choosing the right kind of sling. They discuss slings made from chain, wire rope, fiber rope, and synthetic webbing. The needs of most of our customers are sufficiently met with webbing slings. However, it is always important to assess each load before choosing the right sling for the lift.

OSHA recommends synthetic web slings when practical due to their strength, convenience, shock absorbency, temperature resistance, and safety. Synthetic webbing slings should be used with caution when dealing with acids and other corrosive substances. They should never be used when they show signs of excessive wear, elongation, or distortion.

The Four Points of Safe Lifting

The OSHA guidance goes on to discuss how to lift safely using four points of reference. Those four points are as follows:

1. Size, Weight, and Center of Gravity

The safest way to lift with a sling is to ensure that the hook is located directly over the center of gravity. Slight variations are workable but getting too far off center can cause big problems. The heavier the weight and the larger the size, the more critical center of gravity is.

2. Lift Angle and Number of Legs

A lift angle is formed between each sling leg and its horizontal line. The smaller that angle is, the more stress is put on the sling legs. It is important to know this angle in relation to the amount of weight being lifted. Smaller angles dictate less weight per lift. Larger angles can tolerate heavier loads.

3. Sling Load Limit

Just like webbing straps and chains used to tie down cargo, slings have working load limits. Each sling has a rated capacity calculated by considering the type and size of the sling and the type of hook being used. It is critical that operators know the rated capacity of their slings before attempting a lift. Manufacturers generally mark slings at the factory.

4. Usage, Care, and Handling

OSHA’s fourth point of reference for safe lifting involves the proper usage, care, and handling of slings and shackles. Their guidance suggests that a history of improper usage increases the risk of accidents with every subsequent lift. In simple terms, bad habits are hard to break.

For each lift, proper care and handling of slings is essential. Slings should be cared for to prevent even minor damage. They should be inspected prior to and following every lift. And they should always be used according to manufacturer instructions and OSHA guidelines.

This concludes our basic summary of OSHA guidelines for safe lifting with slings and shackles. If you ever have a question about safe lifting practices, find the answer before you attempt a lift. Remember that lifting with slings and shackles is always dangerous no matter how many safety precautions you take.

 


Wire Rope Nomenclature for Beginners

Now that Mytee is offering rigging supplies, we are beginning to see an increase in the number of questions for these products. Our customers need to know what they are purchasing before they complete their purchase, and want to ensure that all their questions are answered correctly. For example, we sell a number of different kinds of wire rope for rigging.

wire-rope

Two examples of wire rope products would be our peerless galvanized aircraft cable and peerless fiber core wire rope. If you were to view either of these products on our site, you would see a description complete with a set of numbers that you might not understand. Unfortunately, there is a certain nomenclature assigned to wire ropes that you may not be familiar with unless you have extensive experience with rigging.

Wire rope is normally identified using three features:

  • The number of wires in each strand
  • The number and/or configuration of strands in each rope
  • An indicator of the construction or arrangement of the wires in the rope.

For example, a product designated as ‘6×7 fiber core’ would consist of six strands of seven wires per strand, surrounding a core made of a synthetic fiber. To an experienced rigger, the product designation would be enough to tell him or her whether the product is suitable for his/her purposes or not. Someone who does not possess the same kind of knowledge might look at the product designation and think nothing of it.

Different Rope Cores

The core, or center of a wire rope, indicates how that rope is used and what its capabilities are. Riggers have to fully understand load requirements in order to know what kind of core is most suitable to the needs of the job at hand. There are three primary core options to choose from:

  • Strand Center – This core is made up of a strand of wires either similar or identical to the outer strands. It is the weakest kind of core, yet it is still strong enough to be used for guy wires, suspension bridge cables, and aircraft cable. It is the core of choice for applications in which crushing weights are a concern.
  • Fiber Center – This core consists of pre-lubricated plastic fibers made of a material such as propylene. The advantage of a fiber core is that it stands up to tremendous amounts of pressure. It also tends to do very well against caustic substances that might be damaging to a strand center rope. It is not a good choice for applications involving crushing weight.
  • Independent Center Core – Known formally in the industry as IWRC (independent wire rope center), this kind of core is essentially a separate wire rope made with its own strands and core. Wire ropes made with IWRC cores are the strongest of all. They are generally accepted to be 7% stronger than comparable strand center wire ropes. The increased strength makes IWRC the preferred core for wire ropes that will be used to carry heavy loads.

One last thing riggers need to consider is the lay of wire strands within a rope. A regular lay rope is one in which the individual strands of the rope run opposite to the rope itself. A lang lay rope consists of strands that are laid in the same direction as the completed rope.

Finally, the alternate lay configuration utilizes equal numbers of regular and lang lay strands, woven together alternately. You can see this alternating pattern by laying the wire rope on a flat surface and inspecting the individual strands.

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