Understanding the science behind modular spreader beams

Modular spreader beams are one of many types of lifting beams commonly used throughout the lifting and rigging industry. The question is, what’s the benefit of using a modular beam over forged steel, telescopic spreader beams or center-pick beams? Furthermore, how can a hollow cylinder possibly support such extreme capacities where a steel beam would fail? Understanding the science behind modular spreader beams will provide answers to both questions.

Breaking down the construction of a modular spreader beam, such as those offered by LGH, it’s a rather simple design. Hollow “struts” are sandwiched between end units that contain points to affix high-capacity shackles. Each separate unit is held together with bolts that are tightened, generally, to 110 lb-ft of torque, but higher torque is required on larger capacity setups. One interesting tidbit, while it should NEVER be employed on an active job site, is that when under load, the beam itself can be held together without the bolts. How is that possible, you ask? Let’s take a look.

The science of modular spreader beams is similar to that of this aluminum can, on a much larger scale.To understand this concept, think of an aluminum soda can. A typical aluminum can support up to an impressive 250 pounds before buckling. That is provided the weight is centered and evenly distributed on the top of the can with no side-loading forces. With that visual in mind, you can see how durable a modular spreader beam would be standing up to compression. What does that mean for the downward forces generated from the load? The simple answer is that the compressive forces holding the beam together offset the force generated by the load underneath.

Struts on modular spreader beams are fitted with a bolt aligning collar, ensuring the beam remains perfectly linear. The shackles provide flexibility to the top slings and allow basic geometry to prevent bending forces from being generated. Provided you don’t exceed a 45-degree angle or less than 70-degrees from the horizon, the modular beam can lift far beyond its own weight.

Back to our original question of why choose a modular beam over any other lifting beam variants. We’ve seen projects in which the rigging techniques on site made a modular beam the absolutely the worst choice. While it shouldn’t be done, we’ve seen on some jobs where the crew looped straps around the middle of the beam rather than using the end points. This is an express route to catastrophic failure of the beam and likely leads to loss of life or load. Think again to the aluminum can. It’s far easier to crush the sides of the can than it is to crush from top to bottom. While there are options to provide pick points in the middle of the beam, additional equipment would be required. So for that reason, assume you’re better off with a traditional lifting beam depending on the weight of your load.

Modular spreader beams are well-engineered and incredibly versatile pieces of equipment that save both time and space on your jobsite. A single system can be expanded to numerous sizes and requires only one person to set it up. Available with struts ranging from 1-20 feet long, LGH can set you up with a beam EXACTLY the size you need with reduced freight costs compared to a solid lifting beam.

Now that you understand the science behind modular spreader beams, check out our Modular Spreader Beam section on our web site, our video for Safe and Effective Use of Modular Spreader Beams below or reach out to your local representative for more information.

 

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