wire rope breaking strength vs working load factory

It’s rare for a week to go by here at Industrial Wire Rope without discussions about tensile strength or working load limit. We take it for granted that most people in our industry know there is a difference in the meaning of these terms. Yet, these terms and others are highly interrelated, and we thought an overview of them on one page might be a helpful reference. For those who want to dive deeper into the definitions and how they apply on the job, we’re also providing links to sources with additional information.

Let’s start with Tensile Strength. As we described in a post from 2017, “Tensile strength is a measurement of the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. The tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example breaking.”

In our immediate world, tensile strength is the force required to break the ropes we offer. Tensile strength is determined by testing. Obviously, it is different for every type of rope, being a function of the material and construction of each type.

Although tensile strength is a definitive quantity measuring the force required to break a rope, working load limit is a measure that takes a wide range of variables into account. And always, the tensile strength of a material is greater than the recommended working load limit.

The working load limit provides consideration for factors such as the abrasion, friction and rubbing the rope is subjected to, the variance in temperature extremes it is exposed to, harmful substances that may come into contact with it, age, and even knots in the rope. Working load limit is defined as “the maximum load which should ever be applied to the product, even when the product is new and when the load is uniformly applied”.

Working load limit is always a fraction of tensile strength, allowing for a generous margin of safety. For wire ropes, it’s common for the working load limit to be set at 20% of tensile strength. However, you generally don’t have to be concerned about doing the math on your own. Rope manufacturers typically mark the working load limit on the products, so the information should be readily available to you.

Have you picked up a ratchet strap and saw numbers labeled on the strap, and wonder what they mean? Chances are you"re reading the working load limit or break strength. Every piece of load-bearing equipment states these requirements to let you know how much weight that piece of rigging is capable of securing.

When it comes to securing fragile or heavy loads, it is crucial that the product can secure the load without breaking. Although these terms are normally stated, there is confusion about what these terms mean. Read on below to learn what working load limit, break strength, and safety factor mean.

Many people ask about the working load limit, and this is a term to not mix up with breaking strength. Abbreviated as WLL, it is the rating that should never be exceeded when using a product like a ratchet strap. Before using a piece of load-bearing equipment, always make sure to look at the working load limit before use as it is the maximum allowable loading force.

Something to keep in mind is the working load limit is always 1/3 of the breaking strength. So if a ratchet strap has a breaking strength of 15,000 pounds, then the strap will have a working load limit of 5,000 pounds.

The break strength is equally as important as the WLL. The break strength also refers to the point at which your load-bearing equipment will fail. It is expressed in pounds and/or kilograms, and will actually fail if you go over the required amount.

When a ratchet strap is made with webbing, end fittings, and a ratchet all with a 10,000-pound breaking strength, then the break strength of the overall product will stay 10,000 pounds. However, if the same strap has a ratchet with an 8,000-pound break strength, then that would reduce the product"s strength to 8,000.

Safety factor, also known as Design Factor, determines the ratio between the working load limit and break strength. The working load limit"s rating should never exceed when using a sling or tiedown, and this safety factor provides an allowance for shock loading, G force, and other unforeseen factors.

When selecting a ratchet strap, lifting sling, shackle, or any other product, select the product that has suitable characteristics for the type of load, environment, and attachment to the vehicle.

At US Cargo Control, we want you to be safe when securing heavy loads. If you have any questions about the safety requirements, give our team a call at 800-404-7068 or email us at customerservice@uscargocontrol.com.

The use of rope for any purpose results in friction, bending and tension. All rope, hardware, sheaves rollers, capstans, cleats, as well as knots are, in varying degrees, damaging to ropes. It’s important to understand that rope is a moving, working, strength member and even under the most ideal conditions will lose strength due to use in any application. Maximizing the safety of rope performance is directly related to how strength loss is managed and making sure ropes are retired from service before a dangerous situation is created. Ropes are serious working tools and used properly will give consistent and reliable service. The cost of rope replacement is extremely small when compared to the physical damage or personnel injury that can result from using a worn out rope.

There are basically three steps to consider in providing the longest possible service life for ropes, the safest conditions and long range economy: Selection, Usage and Inspection.

Selecting a rope involves evaluating a combination of factors. Some of these factors are straight forward, like comparing rope specifications. Others are less qualitative, like color preference or how a rope feels while handling. Cutting corners, reducing design factors, sizes or strengths on an initial purchase creates unnecessary replacements, potentially dangerous conditions and increased long term costs. Fiber and construction being equal, a larger rope will outlast a smaller rope, because of greater surface wear distribution. By the same token, a stronger rope will outlast a weaker one, because it will be used at a lower percentage of its break strength and corresponding Work Load Limit with less chance of overstressing. The following factors should be considered in your rope selection: Strength, Elongation, Firmness, Construction and Abrasion.

When given a choice between ropes, select the strongest of any given size. A load of 200 pounds represents 2% of the strength of a rope with a 10,000 Lbs. breaking strength. The same load represents 4% of the strength of a rope that has a 5,000 Lbs. breaking strength. The weaker rope will work harder and as a result will have to be retired sooner. Braided ropes are stronger than twisted ropes that are the same size and fiber type.

Please note that the listed break strengths are average break strengths and do not consider conditions such as sustained loads or shock loading. Listed break strengths are attained under laboratory conditions. Remember also that break strength is not the same as the Work Load Limit.

It is well accepted that ropes with lower elongation under load will give you better control. However, ropes with lower elongation that are shock loaded, like a lowering line, can fail without warning even though the rope appears to be in good shape. Low elongating ropes should be selected with the highest possible strength. Both twisted ropes and braided ropes are suitable for rigging. Size for size, braided rope has higher strength and lower stretch than a twisted rope of similar fiber. See page 390 for additional information on rope elongation.

Select ropes that are firm and hold their shape during use. Soft or mushy ropes will snag easily and abrade quickly causing accelerated strength loss.

Rope construction plays an important role in resistance to normal wear and abrasion. Braided ropes have a basically round, smooth construction that tends to flatten out somewhat over the bearing surface. Flattening distributes wear over a much greater area, as opposed to the crowns of a three strand or to a lesser degree, an eight strand rope.

All rope will be severely damaged if subjected to rough surfaces or damaging edges. All rope must be protected against damaging or abrasive surfaces. Wire rope will score and gouge chocks and bitts creating cutting edges that can damage synthetic ropes. Chocks, bitts, drums and other surfaces must be kept in good condition and free of burrs and rust. Weld beads on repaired capstans, fairleads, etc., are equally damaging, unless dressed down smoothly. Pulleys must be free to rotate and should be of proper size to avoid

Avoid using a rope that shows signs of aging and wear. If in doubt, do not use the rope. Damaged rope must be destroyed to prevent any future use. No visual inspection can be guaranteed to accurately and precisely determine the residual strength of the rope. When fibers show wear in any area, the damaged area must be removed and the rope should be re-spliced or replaced. Check regularly for frayed or broken strands. Pulled strands should be rethreaded into the rope if possible. A pulled strand can snag on a foreign object during usage. Both outer and inner rope fibers may contribute to the strength of the rope. When either is worn the rope is naturally weakened. Open the strand of the rope and inspect for powdered fiber, which is one sign of internal wear. A heavily used rope will often become compacted or hard, which indicates reduced strength. The rope should be discarded and made unusable if this condition is detected. See pages 395 and 396 for additional inspection information.

New rope tensile strength is based upon tests of new and unused spliced rope of standard construction in accordance with Samson testing methods, which conform to Cordage Institute, ASTM and OCIMF test procedures. It can be expected that strengths will decrease as soon as a rope is put into use. Because of the wide range of rope use, changes in rope conditions, exposure to the many factors affecting rope behavior and the possibility of risk to life and property, it is impossible to cover all aspects of proper rope applications or to make generalized statements as to Work Load Limits.

Work Load Limits are the load that a rope in good condition with appropriate splices in non-critical applications is subjected to during normal activity. They are normally expressed as a percentage of new rope strength and should not exceed 20% of the stated break strength. Thus, your maximum Work Load Limit would be 1/5 or 20% of the stated break strength.

A point to remember is that a rope may be severely overloaded or shock loaded in use without breaking. Damage and strength loss may have occurred without any visible indication. The next time the rope is used under normal Work Loads and conditions, the acquired weakness can cause it to break.

Normal Work Load Limits do not cover dynamic conditions such as shock loads or sustained loads, nor do they apply where life, limb or property are involved. In these cases a stronger rope must be used and/or a higher design factor applied.

Normal Work Load Limits are not applicable when rope is subjected to dynamic loading. Whenever a load is picked up, stopped, moved or swung there is increased force due to dynamic loading. The more rapidly or suddenly such actions occur, the greater the increase in the dynamic loading. In extreme cases, the force put on the rope may be two, three or many more times the normal Work Load involved. Examples of dynamic loading would be: towing applications, picking up a load on a slack line or using a rope to stop a falling object. Dynamic loading affects low elongation ropes like polyester to a greater degree than higher elongation, nylon ropes. Dynamic loading is also magnified on shorter length ropes when compared to longer rope lengths. Therefore, in all such applications, normal Work Load Limits do not apply.

IMPORTANT NOTE: Many industries are subject to state and federal regulations for Work Load Limits that supersede those of the manufacturer. It is the responsibility of the user to be aware of and adhere to those laws and regulations.

Work Load Limits as described do not apply when ropes have been subjected to shock loading. Whenever a load is picked up, stopped, moved or swung, there is an increased force due to dynamic loading. The more rapidly or suddenly such actions occur, the greater this increase in force will be. The load must be handled slowly and smoothly to minimize dynamic effects. In extreme cases, the force put on the rope may be two, three or even more times the normal Work Load involved. Examples of shock loading are picking up a tow on a slack line or using a rope to stop a falling object. Therefore, in all applications such as towing lines, life lines, safety lines, climbing ropes, etc., design factors must reflect the added risks involved. Users should be aware that dynamic effects are greater on a low elongation rope such as manila than on a high-elongation rope such as nylon and greater on a shorter rope than on a longer one.

The shock load that occurs on a winch line when a 5,000 Lbs. object is lifted vertically with a sudden jerk may translate the 5,000 Lbs. of weight into 30,000 Lbs. of dynamic force, which could cause the line to break. Where shock loads, sustained loads or where life, limb or valuable property is involved, it is recommended that a much higher design factor than 5 be used.

Remember, shock loads are simply a sudden change in tension, from a state of relaxation or low load to one of high load. The further an object falls, the greater the impact. Synthetic fibers have a memory and retain the effects of being overloaded or shock loaded. Ropes that have been shock loaded can fail at a later time, when used within Work Load Limits.

Any job site that utilizes heavy-duty industrial hardware will have a higher rate of job site hazards than the average workplace. Construction zones, transportation services, and manufacturing plants that rely onindustrial chainsfor hoisting, tie-downs, or tension can create dangerous scenarios if they are not mindful of theworking load limit. Miscalculations can cause even strong chains to warp or even break – leading to dangerous and disastrous consequences.

Properly calculating theworking load limitforindustrial chainsis just one of the preventative measures to take to lower these risks. Even though these chains are made from incredibly durable materials, the load-bearing weight should never exceed or even approach the breaking strength. Theworking load limit(WLL) of a chain is a safety precaution to prevent this from happening.

Lower-grade chains (30, 43, and 70) are most commonly used for construction, tie-downs, towing and logging. While these chains are quite durable and have working load limits of up to 15,800 lbs., they are not safe for overhead lifting or rigging applications.

Grade 80 chainsare made from a steel alloy, meaning it contains additional metals for added strength and durability. Grade 80 chains have a breaking load limit of up to 190,800 lbs. and a WLL of 47,700 lbs. They are extremely rugged and often come in a black lacquer finish, which protects the links from damage and wear.

Grade 100 chainsare 25% stronger than Grade 80 and are most commonly used for chain hoists and overhead or even aerial lifts. This style of chain is available in varying lengths and diameters, which can change the breaking load limit and WLL of the entire chain.

Apart from deciding on the grade, length, and chain link diameter required for the intended application, the WLL is one of the most important factors to note before purchasing. This number is the absolute maximum tension that can be safely applied to anindustrial chainwithout compromising its strength.

The WLL is far lower than the maximum breaking strength of a chain. This is to account for added factors that will create additional tension on the chain apart from the load itself. These factors could include:

If you are buying from a reputableindustrial chain supplier, the WLL should be clearly stated for each chain style option. This number is determined by dividing the minimum breaking strength by the safety factor rating for the chain.

The safety factor is a ratio that states how strong of a weight force the chain can withstand before breaking. For most industrial chains, thesafety factor will be 5:1, meaning that if its working load limit is 10,000 lbs. it can technically withstand 50,000 lbs. before snapping. However, this chain should never be used for a 50,000 lbs. load.

Grade 30 and 43 chains are approved for use with construction, securement, and agricultural use. Galvanized or stainless-steel chains may also be used with marine applications, as they are corrosion resistant. Grade 70 has a far higher strength than 30 or 43 and is generally used for transport tie-downs. And remember that overhead lifting is reserved for Grade 80 and higher-grade chains only.

Finally, be sure to consider other factors that could lower a chain’s strength, such as its age or condition. The WLL is calculated with brand-new chains, not ones that are worn from previous use. This is why close inspection of chains is always necessary before using them for a new load or application.

Theworking load limitforindustrial chainsis not overly complicated, but you should understand the basic concepts when using this type of hardware. Before placing an order from anindustrial chain supplier, always double-check the WLL along with the accurate load calculation.

It turns out that there is little margin of safety with steel cable equipped winches. Why is this? Unlike the lifting industry, the recreational pulling industry is unregulated, consequently winch manufacturers typically equip winches with steel cables with minimum breaking strengths that are very close to the max winch capacities. The lifting industry requires a 5:1 safety factor due to the overhead dangers. The pulling industry does not. In fact many steel equipped winches possess a safety factor of less than 1.5!

Take for instance common 5/16 steel cable supplied on most winches up to 10K capacities. The working load limit (WLL) on common 5/16 steel cable is only 2000 pounds. The minimum breaking strength is approximately 10K pounds. So in many cases a 10K winch can be supplied with a steel cable with a minimum breaking strength of 10K. Take a look at the steel cable writeup from our friend Tyler at Roundforge (Roundforge.com) for more comprehensive data on steel cable types and classes.

One of the reasons that cable failures are relatively infrequent is mostly due to vehicle recoveries being in the 4-5k pulling load range, well below the cable breaking strength. Also, often times steel cables can possess ultimate strengths above the minimum breaking loads. So what’s the takeaway here? Due to the little margin of safety in steel cables, make sure you properly maintain the cable and be on the lookout for weakening factors like kinks, broken wires etc., and when possible use a snatch block to reduce the cable load.

Picture supplied by our friend James Pickard. James snapped his steel cable while using the UltraHook. The UltraHook possesses a breaking strength of 31,000 pounds(hook opening) to 48,000 pounds(shackle pin mount). Engineering facts matter.

WARN | CRAWL Magazine | SpiderWebShade | Carolina Metal Masters | TNT Customs | sPOD | Rock Krawler Suspension | BFGoodrich Tires | Raceline Wheels | Radflo Shocks | Savvy Off Road | Synergy Manufacturing | Off-Road Solutions | 4WD Toyota Owner Magazine | Overland Journal | Expedition Portal | Barlow Adventures | I4WDTA – The International 4-Wheel Drive Trainers Association LLC | Ultra4 Racing | ULTRA4 EUROPE | King of The Hammers | COMEUP | Mile Marker Winch | Superwinch | 4×4 Magazine | XTREME4x4MAGAZINE | Jp Magazine | Extreme 4×4 Nation | Tread Magazine | Jeepfreeks | Modern Jeeper | Poly Performance | Safe-Xtract | Off-Road Safety Academy – Blue Sky Adventures, Inc. | PITTS 4×4 CO.

Manufacturing companies choose to use Dyneema rope over steel wire rope for heavy lifting applications such as heavy lift slings, crane rope, and other rigging operations because Dyneema rope:

Dyneema fiber rope is made from Ultra-High Molecular Weight Polyethylene (UHMWPE) fiber. Dyneema 12 strand rope is a common Dyneema fibered rope used for heavy-duty rigging applications. USA Rope & Recovery manufactures several different types of Dyneema fiber rope including the popular 12 Strand, and 24 Strand ropes, as well as others. No matter the application, USA Rope provides strong, durable, and efficient rope for the marine, arborist, nautical, off-roading, and other manufacturing industries.

More times than not, Dyneema fiber rope and steel wire rope are compared by most manufacturing companies–likeThe Rigging Company–for certain maritime, mooring, and towing rope applications. Pound for pound, Dyneema fiber rope is up to 15 times stronger than steel and up to 40% stronger than aramid fibers–otherwise known as Kevlar rope. The high-performance strength and low weight of Dyneema rope ensures that it is safer to use than steel wire rope. Ideally, Manufacturing companies want a rope that can withstand tremendous weight while being light enough to move, use, and work with when needed. Traditionally, steel wire rope is used for heavy-duty maritime, rigging, and mooring rope applications. Although steel wire rope is known for being used for heavy-duty rigging, the disadvantage is the serious risks that come from its heavy-weight and uneven breakage behavior. When a steel wire rope breaks, the combination of the enormous energy and incredible force causes unpredictable recoil. This unpredictable recoil comes from how wire rope is coiled. Essentially, wire rope is several strands of metal wire twisted into a helix, forming a composite rope. When breakage occurs, the helix formed rope unravels, creating a snaking behavior which can cause sharp edges of the broken strands to release at a dangerous force. The lack of strength compared to Dyneema rope shows that steel wire rope is more susceptible to breaking. This can increase risk factors for manufacturing companies that use steel wire rope for rigging, mooring, and heavy duty lifting.

For example, when comparing a ⅜ inch 12 Strand Dyneema rope to a ⅜ inch steel wire rope, the 12 strand Dyneema rope is significantly stronger and presents safer breaking characteristics. The ⅜ inch steel wire rope withstands a load of 14,478 pounds. As the video shows, even in the event of a partial rupture, the steel wire ropes higher mass and recoil provides a greater risk over 12 Strand Dyneema rope. With a ⅜ inch 12 Strand Dyneema rope, it can withstand 18,857 pounds. With the Dyneema fibers low mass and recoil, it reduces the risks for manufacturing companies using rigging rope for heavy-duty lifting applications.

Dyneema is 7 times lighter than steel wire rope at the same strength. In the event of a break, the recoil force is considerably less. Furthermore, the different construction of a Dyneema rope shows a linear recoil without any snaking behavior. This is due to the fact that Dyneema rope is manufactured from UHMWPE, which is comprised of extremely long chains of polyethylene oriented in the same direction, resulting in an overlapping effect. The overlapping of the UHMWPE increases the bond of the chains and thereby strengthens the Dyneema fiber. Dyneema rope offers durable characteristics that can withstand an immense amount of strength while having very little weight to the rope. Because Dyneema fiber is lighter and has a lesser impact when breakage occurs, choosing Dyneema rope over steel wire rope is the safer choice for manufacturing companies working with heavy lifting and below the hook rigging applications for the industrial, nautical, and arborist industries.

When choosing the best rope for any maritime, mooring, towing, or heavy-duty lifting application, choose a rope that can withstand extremely heavy loads and has a long enough lifetime to handle external factors in the nautical, industrial, or arborist industry. In order to decide which rope is best for the job, there are four main challenges that rigging, heavy-duty lifting, mooring, and towing ropes need to overcome:

Dyneema rope is the only high modulus synthetic fiber that has been scientifically engineered–from Ultra-High Molecular Weight Polyethylene (UHMWPE)–to overcome all four of these challenges. Dyneema is the world’s strongest fiber producing ropes that are 15 times stronger than steel wire ropes of the same weight and has become one the most trusted fiber ropes over generic HMPE ropes and steel cable wire ropes for all rigging, maritime, mooring, and towing rope applications.

Manufacturing companies that work with maritime and mooring applications need a durable rigging rope to withstand the constant pulling that comes from the rope running through fairleads and over capstans. Also, in heavy-duty lifting and towing applications, ropes come in contact with rough surfaces such as chocks and the vessel’s deck. These applications can potentially provide severe abrasions to the ropes and degrade the exposed fibers, eventually breaking them. Choosing a Dyneema fibered rope provides manufacturers with a durable, lightweight rope that carries an abrasion lifetime that is four times longer than steel wire rope and rope made with regular HMPE and polyester. With Dyneema’s extended abrasion lifetime, manufacturers are choosing Dyneema rope over steel wire rope for all mooring, towing, maritime, and heavy-duty lifting applications throughout the nautical, arborist, and industrial industries.

Bending fatigue occurs every time a rope flexes under tension. For heavy-duty lifting applications, rope experiences potential bending-fatigue every time something needs to be moved. For example, when a steel beam manufacturer has completed a 15-ton custom-made beam for a military-grade application, the finished product needs to be moved onto a truck for shipment. Rigging ropes are then attached to a crane to then lift, move and place the steel beam from the warehouse to the truck. This can wear out the rope. Another example is when the rope runs over fairleads and pedestals in maritime and mooring applications. This stresses the fiber both inside and outside of the rope causing bending fatigue and decreases the useful life of the rope. Certain conditions in towing and mooring applications can also lead to compression fatigue. This happens when ropes become slack during services and the fibers compress. Due to the molecular properties (UHMWPE) engineered to make Dyneema fiber– and its extremely long chains of polyethylene oriented in the same direction–threats of compression and bending fatigue are far less over other synthetic fibers and steel wire ropes.

In all rigging applications, synthetic ropes elongate when over a long period of time when loaded in higher temperatures–commonly referred to as creep. Creep is irreversible and when combined with abrasions or other risks, it can lead to rope failure. With regular HMPE rope, in heavy-duty lifting and towing applications where high loads and high temperatures are constantly a factor, the creep process can accelerate. This can be a major risk for ropes made from generic HMPE. In contrast, Dyneema rope has up to four times longer creep lifetime. When comparing Dyneema fiber to Spectra, another synthetic fiber rope, under 122 degrees Fahrenheit and 600 MPa load, Dyneema rope has a significantly longer creep lifetime than Spectra fiber rope.

eAfter comparing Dyneema rope to steel wire rope–a ⅜ inch 12 Strand Dyneema rope to a ⅜ inch steel wire rope–there is a guarantee that Dyneema rope is 15 times stronger and better at dealing with abrasions over steel wire rope. For manufacturing companies, Dyneema rope is also considered to be superior to Nylon rope due to Dyneema fiber having low ability to stretch, is UV resistant, and possesses an immense amount of strength. USA Rope properly manufactures Dyneema fibered ropes that are synthetically engineered to uphold incredible weight while enduring constant friction for application uses involving heavy-duty lifting, crane rope support, and below the hook rigging.

Understanding that Dyneema fiber rope is better used for manufacturing companies over steel wire rope, USA Rope & Recovery works hard to manufacture the highest quality rope by using top-of-the-line supplies from across the USA. Dedicating time and effort to finding the next best and technologically advanced products in the market is our main goal at USA Rope in order to help our customers gain the best competitive advantage in their respective field. USA Rope & Recovery also manufactures additional ropes including Spectra, Nylon, Polyester, Polypro, and Kevlar (Aramid) fiber ropes. No matter the application, USA Rope is a leader in custom rope manufacturing for industries including nautical, industrial, arborist, and marine.

In general, running rigging should be replaced whenever it shows visible signs of damage – core hemorrhaged through the cover, several broken strands close together, “rot” from UV exposure, or green and stiff from disuse. There’s a rule of thumb, but it varies rigger to rigger. The Rule of thumb says to replace all rigging hardware every 5-10 years. However, depending on how much everyday usage, weight, and environmental factors the rigging ropes take on can make the rule of thumb shorter or longer.

There are multiple different types of synthetic winch lines available today, many of them are made from Dyneema fibers, while others are made fromPolyester,Nylon,Spectra, orKevlar. Each fiber has benefits and disadvantages and can be chosen depending on your unique application. Spectra is similar to Dyneema fiber but is not as strong or as durable. Because of its strength and durability, Dyneema is the premier synthetic fiber for winching applications.

Minimum Breaking Strength (MBS) and Working Load Limit (WLL), formerly known as Safe Working Load (SWL), are two important strength ratings when it comes to rigging and safety equipment. They vary based on what type of rigging or safety equipment and are identified by manufacturers.

MBS is precisely what it says, the minimum amount of weight you can put on the equipment that would result in equipment failure. This manufacturer’s recommendation is its maximum weight load for lifting equipment.

Due to legal implications the US, and shortly after Europe, began using “working load limit” rather than SWL “safe working load”. However, they mean the same thing.  WLL or SWL is “the breaking load of a component divided by an appropriate factor of safety giving a safe load that could be lifted or carried.”

Both of these load numerical limits are assigned to lifting and/or rigging equipment. Overhead lifting equipment include hooks, shackles, straps, rope, line and equipment like cranes or other lifting devices. Manufacturers assigned a working load limit on these products.

The incorporation of various materials changes your working load limits. The strength of these materials is known as the mechanics of materials and deals with the behavior of solid objects and how they handle stress and strain.

The strength of a material is its ability to withstand an applied load without failure. A load applied to a mechanical member will induce internal forces within the member called stresses when those forces are expressed on a unit basis. The stresses acting on the material cause deformation of the material in various manner. Deformation of the material is called strain when those deformations too are placed on a unit basis. Therein lies the importance of knowing what materials are working with and what your load limits are for all equipment involved in your rigging and hauling.

There is a wide array of rigging accessories needed in hoisting and rigging. Henssgen Hardware is an industrial rigging hardware supplier. The rigging hardware we carry include: snap hooks, pulleys (fixed eye and swivel with single and double sheave), quick links, shackles, wire rope clips, drop forged clevis grab and clevis slip hooks.

Our rigging hardware is manufactured in stainless steel, solid brass, die cast zinc alloy, zinc plated malleable iron and zinc plated. All of our snap hooks are equipped with stainless steel springs. When dealing with expensive equipment, important loads and your safety, you must have quality hardware. Henssgen is committed to providing each one of our customers with the best.

The definition for safe working load is the breaking load of a component divided by an appropriate factor of safety giving a safe load that could be lifted or be carried.

The working load limit is that it is the maximum mass or force which a product is authorized to support in general service when the pull is applied in-line, unless noted otherwise, with respect to the centerline of the product.

Working load limits are calculated on straight line pulls only. Never side load. Other conditions such as extreme temperatures, chemicals solutions or spills, vapors, or immersion in salt water can reduce the Working Load Limit. Welds to any steel products can also void out a Working Load Limit rating.

The Working Load Limit is the maximum load which should ever be applied to the product, even when the product is new and when the load is uniformly applied – straight line pull only. Avoid side loading. All catalog ratings are based upon usual environmental conditions and consideration must be given to unusual conditions such as extreme high or low temperatures, chemical solutions or vapors, prolonged immersion in salt water, etc. Never exceed the Working Load Limit.

The term “Proof Test” designates a quality control test applied to the product for the sole purpose of detecting defects in material or manufacture. The Proof Test Load (usually twice the Working Load Limit) is the load which the product withstood without deformation when new and under laboratory test conditions. A constantly increasing force is applied in direct line to the product at a uniform rate of speed on a standard pull testing machine. The Proof Test Load does not mean the Working Load Limit should ever be exceeded.

Do not use breaking strength as a criterion for service or design purposes. Refer to the Working Load Limit instead. Breaking Strength is the average force at which the product, in the condition it would leave the factory, has been found by representative testing to break, when a constantly increasing force is applied in direct line to the product at a uniform rate of speed on a standard pull testing machine. Proof testing to twice the Working Load Limit does not apply to hand-spliced slings. Remember: Breaking Strengths, when published, were obtained under controlled laboratory conditions. Listing of the Breaking Strength does not mean the Working Load Limit should ever be exceeded.

An industry term usually computed by dividing the catalog Breaking Strength by the catalog Working Load Limit and generally expressed as a ratio. For example: 5 to 1.

A load resulting from rapid change of movement, such as impacting, jerking or swinging of a static load. Sudden release of tension is another form of shock loading. Shock loads are generally significantly greater than static loads. Any shock loading must be considered when selecting the item for use in a system.

Wire rope is a collection of metal strands that have been twisted and wound to form the shape of a helix with the purpose of supporting and lifting heavy loads and performing tasks that are too rigorous for standard wire. On shipping docks, rigging, and load bearing equipment, wire rope is attached to swivels, shackles, or hooks to lift a load in a controlled, even, and efficient manner.

The uses for wire rope include adding support to suspension bridges, lifting elevators, and serving as additional reinforcement for towers. The design of wire rope, with its multiple strands wrapped around a stable core, provides strength, flexibility, and ease of handling for applications that have bending stress.

Individual designs of wire rope involve different materials, wire, and strand configurations as a means for supporting and assisting in the completion of lifting or supportive applications.

The term wire rope encompasses a wide range of mechanical tools that are made to perform heavy and extreme lifting jobs. Wire rope is a complicated and complex tool with multiple moving parts capable of moving in unison. A 6 by 25 wire rope has 150 outer strands that move as one in an intricate pattern supported by a flexible core.

An essential part of the design of wire rope is the required clearance between the strands to give each stand the freedom to move and adjust when the rope bends. It is this unique feature that differentiates wire rope from solid wire and other forms of cable.

The basic element of wire rope is wire that is used to configure, shape, and form the rope. Typically, steel, stainless steel, and galvanized wires are the first choice with aluminum, nickel alloy, bronze, copper, and titanium being second possibilities. The choice of wire is dependent on the type of work the wire is going to be used to perform with strength, flexibility, and abrasion resistance being the major determining factors.

Stainless steel wire rope has all of the basic qualities of galvanized and general wire rope with the added benefits of corrosion and rust resistance; this makes it the ideal choice for harsh and stressful conditions.

Steel wire rope is classified as general purpose wire rope and comes in a wide variety of sizes, diameters, and strengths. It is the most common type of wire rope and is used for several industrial, manufacturing, and construction applications.

Before going further into the discussion of how wire rope is made, it is important to understand the numbers used to describe each type. All wire ropes have a core around which wires are wound. The various styles of cores vary according to the construction and design of the requirements of the wire rope that is being produced.

Wire rope is classified by the number of strands it has as well as the number of wires in each strand. The most common classification is a seven wire rope that has one strand in the center and six around its circumference. This type of wire rope is lightweight with a very simple construction. The majority of wire ropes are more complex and intricate with multiple intertwining strands and wires.

What must be understood about wire rope is that it has a complicated configuration. It is actually wires wrapped around wires to form bundles that are wrapped around other bundles. In the case of a seven wire wire rope, the core has bundles of wires wound around it; this can be seen in the image below.

The first step in wire rope creation is the production of wire strands where wires are wound around a single core wire. The number of wires included in the strand is dependent on the specified strength, flexibility, and size requirements of the rope. Once the strand is completed, it is straightened before being moved to wire rope construction.

Like wire ropes, strands have different patterns; patterns are the arrangements of the wires and their diameters. Though most strands have a core, there are strand patterns that have three or four wires without a core that are referred to as centerless strands. The design of each strand pattern is meant to enhance the strength of the wire rope and improve its performance.

For a multiple layer strand, the layers of wire are placed over one another in successive order. The placement of the wires on top of each other must be such that they fit smoothly and evenly.

The Warrington pattern is like the multiple layer pattern with one variation. Like the multiple layer pattern, the inner wires and the core are the same and have the same diameter. The difference is in the outer layer, which has wires of alternating sizes of large and small with larger diameter wires laying in the valleys of the inner wires.

All of the wires of a filler pattern are the same size. What makes this pattern unique is the insertion of small wires in the valleys of the inner wires to fill the gap between the inner and outer layer.

The flattened strand pattern is also known as the triangular strand, which can be triangular or oval. Three round wires form the core. The outer flattened surface has a greater sectional metallic area; this makes this pattern stronger and longer lasting.

The core of a wire rope runs through the center of the rope and can be composed of a variety of materials, which include synthetic fibers, natural fibers, a single strand, or another wire rope. The core supports the wound strands, helps maintain their position, is an effective lubricant carrier, and provides support.

Wire ropes with fiber cores are restricted to light loads and are not used in severe, harsh, or stressful conditions. Polypropylene and nylon are types of synthetic fiber cores and can be used in conditions where there is exposure to chemicals.

Cores made of wire are classified as independent wire cores. The core of a wire rope with a wire core is actually a wire rope with another wire rope serving as the core, as can be seen in the diagram below. These types of wire ropes are used where the rope will be exposed to exceptional resistance and crushing.

A strand, or wire strand core, is exactly like the rest of the strands of the wire rope with wires of the same diameter and size as the other strands.

The choice of core and creation of the strands are the simplest yet most essential parts of wire rope construction. Wire rope lays, the method used to wind the strands, is more complex and involves several choices.

Lay is a term used to describe three of the main characteristics of wire rope: direction, relationship, and linear distance. The strands can be wrapped around the core going right or left. Right or left refers to the direction of the strands wrapped around the core and the wires within the strands. The linear distance is how far a strand moves when it is making a revolution around the core.

In a regular lay, the wires and strands spiral in opposite directions. With a right hand regular lay, the wires spiral to the left and the strands to the right. In the left hand regular lay, the wires spiral to the right and the strands to the left. This type of lay is easy to handle but wears out quickly because the crown wires are in contact with the bearing surface.

In the Lang, or Albert, lay, the wires and strands spiral in the same direction with right hand lay being the most common. The wires in a Lang lay appear to run parallel to the center line of the rope. The difficulty with Lang lay wire ropes is handling since they tend to kink, twist, and crush.

Wire rope is an exceptionally strong tool that has been configured and designed to withstand the stress placed upon it through rigorous and continual use. In most applications, wire rope has to endure extreme stress and strain. It is for these reasons that coatings have been developed to protect wire rope from abrasions, corrosion, UV rays, and harmful and damaging chemicals.

Three main types of coatings are used to protect wire rope: polyvinyl chloride (PVC), polypropylene, and nylon. Of the three types, PVC is the most popular.

In cases where there are severe and hazardous working conditions, polypropylene is the recommended choice since it is capable of protecting wire rope against corrosion and chemical leaching. Additionally, it is resistant to impact damage and abrasion. Polypropylene is a tough, rigid, and crystalline thermoplastic that is made from a propene monomer and is resilient as well as inexpensive.

Braided wires are electrical conductors made up of small wires that are braided together to form a round tubular braid. The braiding and configuration of braided wire makes them very sturdy such that they do not break when flexed or bent. Braided wires are widely used as conductors, are commonly made from copper due to copper"s exceptional conductivity, and can be bare or coated depending on the application.

Braided wire can be round and tubular or flat. Round tubular braids fit in most spaces where flat braided wire will not. Flat braided wire begins as round braided wire which is flattened on a capstan. They are exceptionally strong and designed for medical and aircraft applications.

Metals used to make wire rope are various grades of stainless steel, bright steel, and galvanized steel. Though the majority of wire rope manufacturers use these three metals, other metals such as copper, aluminum, bronze, and monel are also used on a limited basis.

The most important aspect of wire rope is the wire and the metal from which it is made. The strength and resilience of wire rope is highly dependent on the quality of metal used to make it, and these are essential factors to be considered when purchasing it.

Bright steel wire does not have a coating and is rotation resistant, (designed to not rotate when lifting a load). It is drawn from hot rolled rods that are put through a die to match its specific dimensional tolerances, mechanical properties, and finish. Bright wire is used as a single line in conditions that require a rope that will resist cabling.

Galvanized steel has a zinc coating for corrosion resistance and has the same strength and durability as bright steel. Environmental conditions determine the use of galvanized steel. In mildly severe and slightly harsh conditions, galvanized steel wire is an economical replacement for stainless steel.

In the manufacturing process, galvanized wire goes through the process of galvanization, a method of coating steel wire with a protective and rust resistant metal. Galvanized wire is exceptionally strong, rust resistant, and flexible enough to meet the needs of a variety of applications.

Stainless steel does not have the same strength and endurance as bright steel or galvanized steel but has the many benefits commonly associated with stainless steel, such as resistance to stains, wear, rust, and corrosion. More expensive than the other two metals, stainless steel has the added benefit of lasting longer and providing exceptional performance.

Wire rope made from copper is mostly used for electrical applications due to its exceptional electrical characteristics. The benefits of copper wire rope are its durability, flexibility, and resilience compared to standard copper wire. The strength of copper wire rope is seen in its use in applications where there are vibrations and shaking.

The wire rope lubrication process begins during its fabrication and continues during its use. Lubrication of wire rope is designed to lower the amount of friction it endures and provide corrosion protection. Continued lubrication increases the lifespan of wire rope by preventing it from drying up, rusting, and breaking.

The types of lubricants for wire rope are penetrating or coating with coatings covering and sealing the outside of the rope. Penetrating lubricants go deep into the rope and seep into the core where they evaporate to form a thick coating or film.

The application of the lubricant is dependent on the type of core. Fiber cores absorb the lubricant and serve as a reservoir that retains the lubricant for an extended period of time. With metal cores, the lubricant is applied as the wire is twisted into strands to give complete saturation and coverage of the wires.

There are several types of greases that are used as wire rope lubricating agents and are made up of oil, a thickener, and additives. The essential components are the base oil and additives, which influence the behavior of the grease. The thickener holds the base oil and additives together. The amount of base oil in a grease is between 70% and 95% with an additive of 10%.

The additive in grease enhances the positive properties of the oil and suppresses the negative properties. Common additives are oxidation and rust inhibitors as well as pressure, wear, and friction reducing agents.

Of the many choices for lubricants, vegetable oil is the easiest to use and penetrates the deepest. The design of the additives for vegetable oils gives them the necessary qualities required to penetrate deep into a wire rope. The exceptional penetration provides protection against wear and corrosion. Since vegetable oil is a fluid, it helps in washing the wire rope to remove external abrasive contaminants.

Wire rope is widely used in machines, structures, and varied lifting applications. Its type, size, and requirements are determined by how it will be used. Regardless of its use, wire rope guarantees exceptional strength and provides high quality and excellent performance.

The lifting of heavy loads for centuries involved the use of hemp rope or chains, neither of which was a guaranteed or substantial method. Early in the 18th Century, between 1824 and 1838, Wilhelm Albert, a German mining engineer, combined the twisting of hemp and strength of chains to create today‘s wire rope.

The most common use of wire rope is as a part of a crane hoist wherein it is attached to the hook of the hoist and wrapped around a grooved drum. The tensile strength and durability of wire rope makes an ideal tool for lifting and keeping loads secure. Though it is used in several industries, it is very popular for production environments wherein materials need to be lifted quickly and efficiently.

In addition to its many lifting applications, the strength and stability of wire rope is useful in other applications, especially in the aerospace industry. Pedals, levers, and connectors in the cockpit of an aircraft are connected with wire rope. The wires provide for the passage of power between systems and mechanisms; this allows control of the aircraft. Wire rope is used to control propeller pitch, cowl flaps, and the throttle. It also assists in lowering and minimizing vibrations.

Tires are reinforced with wire rope to increase their durability and strength. All automotive production environments make use of wire ropes for supplying materials, moving heaving loads, and positioning equipment. Wire rope can be found in the production of steering wheels, cables, exhausts, springs, sunroofs, doors, and seating components.

As surprising as it may seem, the place that wire rope has the greatest use is in the home, where its strength, long life, endurance, and resilience provide guaranteed protection and performance. The main reason wire ropes are so popular for home use is cost.

Inexpensive, easy to obtain, easy to install, and easy to maintain, wire ropes provide an additional method for performing home repairs and structural support. Their excellent flexibility and sturdiness combined with their invisibility has made wire rope an ideal solution to several home maintenance issues. It is used to support staircases, fences, decks, and hang plants.

The search and production of crude oil has relied on wire ropes for centuries to lift drill bits, insert shafts, and support oil rigs on land and the water. When equipment, machinery, and tools have to be lowered into the depths of the earth and sea, wire ropes are the tool that the oil industry relies on to do the job.

Many of the tasks of oil production require tools that are capable of enduring severe and harsh conditions. Wire ropes have to withstand enormous pressure, extraordinary stress, and a wide range of temperatures. The use of wire rope includes maintaining oil rig stability and moorings for offshore rigs.

Wire rope has long been a standard component for the transportation industry, from the cable cars of San Francisco to the lift chairs for ski resorts. For many years, cable cars have relied on heavy duty cables (wire ropes) to be pulled by a central motor from multiple locations. It is a method of transportation that has existed for centuries.

In Europe, funiculars use cables that hang from a support to move cars up and down a mountain with cables moving in opposite directions. The word funicular is from the French word funiculaire, meaning railway by cable. The terms wire rope and cable are used interchangeably when discussed by professionals. The first part of funicular, or funiculaire, is from the Latin word "funis," meaning rope.

The major use for wire ropes in the food and beverage industries is as a means for lifting and moving heavy loads. Wine barrels and containers full of ingredients are lifted and placed through use of cranes and wire ropes. They are also part of conveyor systems that move products from one station to another.

From the beginnings of amusement rides up to the present, wire ropes have been an essential part of attraction construction and safety. They pull cars on roller coasters, hold cabins that swing, and move carriages through haunted houses. The main concern of amusement parks is safety. The strength, stability, and guaranteed performance of wire ropes ensures that people who attend amusement parks will have a good time and stay safe.

The rigging used to complete the stunts in modern movies depends on wire rope for safety. Much like in amusement rides, wire ropes protect performers from injury and harm as they hang above a scene or carry out an impossible move.

The live theater industry uses wire ropes to raise and lower curtains, support overhead rigging, and hold backdrops and scenery pieces. During a production, rapid and efficient movement is a necessity that is facilitated by the use of wire ropes.

Wire rope is a tool that we tend to envision as indestructible, unable to succumb to any form of damage. Though it is exceptionally sturdy and strong as well as capable of enduring constant use, it is just as susceptible to breakdown as any other tool.

To avoid serious harm and damage, wire ropes should be scheduled for regular inspections. There are situations that can damage or break a wire rope; these should be understood prior to the problem arising.

Guide rollers have the potential to damage and cause abrasions on wire rope if they become rough and uneven. Of the various elements of a crane and lift, guide rollers have the greatest contact with the mechanism‘s wire rope. Regular inspection of guide rollers will ensure they are not damaging the rope or causing abrasions.

Bending is normally a regular part of wire rope usage; this occurs repetitively as the rope passes through a sheave. As a wire rope traverses the sheave, it is continually bent and develops cracks or breaks. The cracking and breaking are exacerbated by movement on and off the groove of the drum. Normally, the breakage happens on the surface and is visible. Once it appears, it accelerates to the core of the rope.

A bird cage is caused by a sudden release of tension and a rebound of the rope. This type of break requires that the rope be replaced since the place of the break will not return to its normal condition.

Wire ropes are multi-layered; this makes them flexible and torque balanced. The layering inside and outside creates flexibility and wear resistance. Relative motion between the wires causes wear over time, which leads to internal breakage. The detection of these breaks can be indicated by an electromagnetic inspection that calculates the diameter of the rope.

Kinked wire rope is caused by pulling a loop on a slack line during installation or operation; this causes a distortion in the strands and wires. This is a serious condition that necessitates rope replacement.

Corrosion damage is the most difficult cause of wire rope damage to identify, which makes it the most dangerous. The main reason for corrosion is poor lubrication that can be seen in the pitted surface of the rope.

The types of damage and problems listed here are only a small portion of the problems that can be caused if a wire rope is not regularly lubricated and inspected. Various regulatory agencies require that wire ropes be inspected weekly or monthly and provide a list of factors to examine.

As with any type of heavy duty equipment, wire rope is required to adhere to a set of regulations or standards that monitor and control its use for safety and quality reasons. The two organizations that provide guidelines for wire rope use are the American Society of Mechanical Engineers (ASME) and the Occupational Safety and Health Administration (OSHA).

All wire rope manufacturers and users closely follow the standards and guidelines established by OSHA and ASME. In the majority of cases, they will identify the specific standards they are following in regard to their products.

OSHA‘s regulations regarding wire rope fall under sections 1910, 1915, and 1926, with the majority of the stipulations listed in 1926 under material handling, storage, use, and disposal.

"Running rope in service shall be visually inspected daily, unless a qualified person determines it should be performed more frequently. The visual inspection shall consist of observation of all rope that can reasonably be expected to be in use during the day‘s operations. The inspector should focus on discovering gross damage that may be an immediate hazard."

"The inspection frequency shall be based on such factors as rope life on the particular installation or similar installations, severity of environment, percentage of capacity lifts, frequency rates of operation, and exposure to shock loads. Inspections need not be at equal calendar intervals and should be more frequent as the rope approaches the end of its useful life. Close visual inspection of the entire rope length shall be made to evaluate inspection and removal criteria."

ASTM A1023 covers the requirements for steel wire ropes with specifications for various grades and constructions from ¼ in. (6 mm) to 31/2 in. (89 mm) manufactured from uncoated or metallic coated wire. Included are cord products from 1/32 in. (0.8 mm) to 3/8 in. (10 mm) made from metallic coated wire.

United States Federal Spec RR W 410 covers wire ropes and wire seizing strands but does not include all types, classes, constructions, and sizes of wire rope and strands that are available. The purpose of Spec RR W 410 is to cover more common types, classes, constructions, and sizes suitable for federal government use.

Wire rope and wire seizing strand covered by United States Federal Spec RR W 410 are intended for use in general hauling, hoisting, lifting, transporting, well drilling, in passenger and freight elevators, and for marine mooring, towing, trawling, and similar work, none of which are for use with aircraft.

API 9A lists the minimum standards required for use of wire rope for the petroleum and natural gas industries. The types of applications include tubing lines, rod hanger lines, sand lines, cable-tool drilling and clean out lines, cable tool casing lines, rotary drilling lines, winch lines, horse head pumping unit lines, torpedo lines, mast-raising lines, guideline tensioner lines, riser tensioner lines, and mooring and anchor lines. Well serving wire ropes such as lifting slings and well measuring are also included in API 9A.

Wire rope is a collection of metal strands that have been twisted and wound to form the shape of a helix with the purpose of supporting and lifting heavy loads and performing tasks that are too rigorous for standard wire.

Individual designs of wire rope involve different materials, wire, and strand configurations as a means for supporting and assisting in the completion of a lifting or supportive task.

Working Load Limit (WLL), is maximum allowable weight.  If that isn"t clear, cable manufacturers are saying, "Don"t ever put more than X weight on this cable."

Working Load Limit is determined using the Minimum Breaking Strength (MBS). For wire rope that we use in winch cables the WLL is 1/5 the Minimum Breaking Strength. Put another way:

The "5" in the equation above is called the Design Factor. In hoisting, design factors are for when Kevin screws up the rigging and overloads a component. The design factor ensures that the I-beam Kevin rigged up incorrectly doesn"t fall and kill Bob. If you think "5" is a crazy amount of design factor, or that design factors sound dumb, there are plenty of construction videos on YouTube that show that people still manage to exceed the MBS on critical rigging, even with high design factors. In fact, some hoisting operations actually call for a design factor of 10!

The first thing you should know about your winch cable is that its Working Load Limit is far below whatever you"re doing with it. A 5/16" cable has a WLL of 1980 lbs and a 3/8" winch cable has a WLL of 2880 lbs.

How did we calculate the loads of being stuck? We used the "mire" factor in a US Army recovery manual. They aren"t perfect, but they provide us with a rule of thumb.

So, what did you find out? Basically, your winch cable is weak. Assuming all your other gear is properly rated, your winch cable is likely to be the weakest link in your recovery setup. If we ignore the fact that there is practically no design safety factor, we can see in the chart that it"s easy to approach or exceed your winch cable"s breaking strength. This is why winch cables break on the trail.

Minimum Breaking Strength of 9800 lbs, giving us a design factor of 5. The WLL of 5/16" winch cable is about 20% of the WLL of a 3/4" shackle. How come no one is losing their minds!?!?!?!?!?

As we saw above in our charts, in perfect condition there is little margin for safety with a winch cable. We aren"t telling your to swap to a bigger winch cable. You"d end up with a short winch cable, that would be difficult to use on the trail. But there are some things you can do to keep your winch cable from breaking.

A snatch block effectively doubles the power of your winch and will nearly double the strength of your rigging. It also halves the length of winch line available, but you can make this up with a winch extension strap. You have the option of doing a long distance, single line pull, or a shorter distance double line pull. In any case, it"s more versatile than just having a fat, short winch cable.

Second, you can lube your winch cable.Winch ca