Matt Kral, Rigging Content Specialist, LGH
Modular spreader beams are one of many types of lifting beams commonly used throughout the lifting and rigging industry. But what's the benefit of using modular spreader beams over forged steel, telescopic spreader beams or center-pick beams? 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 these questions.
Breaking down the construction of a modular spreader beam reveals it's a rather simple design. Hollow "struts" are sandwiched between end units that contain points to which high-capacity shackles can be affixed. Each separate unit is held together with bolts that are tightened, generally to 110 pound-feet of torque, but higher torque is r
equired on larger-capacity setups. While it should never be employed on an active jobsite, one interesting tidbit is that, when under load, the beam itself can be held together without the bolts. How is that possible? Let's take a look.
To understand this concept, think of an aluminum soda can. A typical aluminum can is able to support up to 250 pounds before buckling, provided the weight is centered and evenly distributed on top of the can with no side-loading forces. With that visual in mind, you can see how durable a modular spreader beam standing up to compression can be. What does that mean for the downward forces generated from the load? The simple answer is 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 beams remain 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 go under 70 degrees from the horizon, the modular beam can lift far more than its own weight.
Going back to the original question, we've seen projects in which rigging techniques on-site made a modular beam the absolute worst choice. While it shouldn't be done, we've seen crews loop straps around the middle of the beam rather than the end points. This is an express route to catastrophic failure of the beam and often leads to loss of life or load. Think again about the aluminum can: It's far easier to crush the sides of the can than it is to crush it from top to bottom. While there are options to provide pick-points in the middle of the beam, additional equipment would be required. For this 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 up.
For more information, visit www.RentLGH.com/BIC or call (800) 878-7305.
