Spreader bar or Lifting Beam

When you are trying to decide which style of below the hook lifting device you need to know the difference between spreader bars and lifting beams and to make the correct choice you need an idea of the pros and cons of each.

The Spreader Bar:

Spreader bars are the standard to below the hook lifting device. It consists of a long slender structural body with a set of lugs at each end one pointing up and one pointing down. The top set of rigging general comes to a point along an angle of 45-60 degrees and is attached to the hook on the crane. The lower rigging hangs vertically and connects to the load being lifted.  If you haven’t read anatomy of a spreader bar you should read that first.

The Lifting Beam:

A lifting beam is a below the hook lifting device that performs the same function as a spreader. It consists of a body and a set of lugs just like a spreader bar but lifting beams generally have one lug on the top in the center and 2 or more lugs along the bottom. The top center lug hooks directly to the crane with no need for upper rigging and the bottom lugs are used to connect to the load in a variety of methods.

Basepoint Lifting Beam

The main difference between the two comes down to the engineering. A spreader bar has a very elegant mathematical solution that eliminates opposing loads causing it to act like a pure column. This effect makes spreader bars very efficient at transferring loads and have a much higher capacity then lifting beams for their given size. The downside of spreader bars is that they require upper rigging. This upper rigging comes at a cost for the equipment but also requires a lot more hook height on a crane to lift a given load.

The second difference is that spreader bars can easily made to be telescopic. By constructing the spreader bar using hollow structural steel material you can get two or more pieces to slide inside each other. This allows spreader bars to become 2-3 times larger than the collapsed length allowing the user to have a much more versatile lifting device. In the mobile crane world this distinction is really important as carrying rigging out to site can be expensive and constrained by what they can fit on the crane or truck.

A lifting beam is used when hook height and clearance are important. This is because there is no top rigging and connecting your crane directly to the beam via the top lug eliminates the wasted height that the rigging takes up. This allows you to lift your load a lot higher on a given crane using a lifting beam. However, because the transverse loads are not balancing through the top rigging like on a spreader bar you end up with a bending moment going through the bar. Building the beam strong enough to cope with this bending moment means lifting beams are heavier than spreader bars for an equivalent spread and capacity. The length of of the beam plays a huge roll in this calculation and the difference is sizes becomes increasingly more apparent as the spread increases. So when would you want to use a lifting beam? Lifting beams are commonly used for indoor shop cranes. When your hook height is limited as much as indoor cranes and you don’t need to transport the beam to the worksite every day it makes sense to use a lifting beam not a spreader bar.

Manufacturing

A bit needs to be said about building telescopic spreader bars vs lifting beams since each comes with its own challenges. Spreader bars will require pins, holes drilled in long tubing and a tubing selection that can slide in each other (Stocking Spreader Bar Material). All of these process require a special machine or technique to manufacture. Lifting beams on the other hand are heavier but simpler requiring at minimum an I-beam which can be purchased along with a couple lugs welded on it. Lifting beams give you the flexibility to get creative with the design a bit more than spreader bars. A personal favorite of mine is to make lifting beams out of two formed channels that bolt together. This requires a machine to cut and bend plate steel but allows you to make the channel any height (for exactly the required strength) and doesn’t require welding.

Spreader Bars

PROS:

  • Cheaper per foot and per ton of capacity
  • Potentially telescopic for improved reach with smaller footprint

CONS:

  • Lots of rigging required
  • Lots of headroom required for upper rigging
  • more complexity with pins, lugs, tubes etc.

Lifting Beams

PROS:

  • Efficient use of crane height because of lack of top rigging
  • Simple to build - one structural member and some lugs
  • potentially weldless design

CONS:

  • Achieving 20ft reach requires 20ft beam (hard to transport)
  • Size of beam increases dramatically with size.
  • Expensive
spreader bar end connection design

I hope this article clears up any confusion about the difference between spreader bars and lifting beams. They are often verbally used interchangeable so it can be confusing realizing there is actually a difference.  If you are thinking about building spreader bars or lifting beams I encourage you to have a look at what we offer by downloading this example spreader bar: Free spreader bar drawings