spreader bar

[stumper120]

So I wound up getting a gmk2035. A little smaller than I wanted but I could not beat the price and so far it is incredible for tree work. However some local framers want to use me for non tree related stuff and it sounds like I need a spreader bar. One guy says he prefers a 16' bar as they build the truss roof system on the ground and set it in sections. What do you guys recommend? Im sure they need to be certified.

 

[Knepptune]

It all depends on how much the roof sections weigh. An extra 1k on the hook can make the difference on moving the crane or not. We've got several different spreaders and our 20' gets used more then any others. Second would be the 32' spreader. Its for 70-96' clear span trusses. The 20' is just a peice of c channel with square tubes on each end and a hook in the middle. Use a 20' 2-legged chain. The chain gets hooked to the ball then each leg is dropped through the tube on each end. So the chain hangs down 10'. The spreader is hooked to the ball as well. Its probably 6' c channel. I wouldn't want to hang much more then 60' trusses on it tho. The 32' spreader is a big 14' I-beam. Its heavy tho.

We built both of them and have never had any problems.

 

[old-iron-habit]

We built all our spreader bars in house. Some out of heavy wall 10" tube with connectors so we could even go to a 4 way spreader. We did have a structural engineer on staff that took our ideas and drew them up complete with calcs to legitimize them. Us field guys usually had them over designed and they got lighter when he put the pencil to them. Many ended up needing only 6" tube with a five to one safety margin. As stated above it makes a huge difference as to where you hook your spreaders up to them.

 

[Nige]

For our spreaders we generally used thick-wall tubing slotted at each end then welded an anchor plate in each slot with 2 drilled holes it it for shackles. That way all the vertical load is transmitted directly through the anchor plates and only a relatively small horizontal component goes into the tube in compression, so the tube doesn't need a really thick wall because it's not taking load. The downside is that the upper slings might need to be quite long to keep the sling angle within limits if you require a large separation between lifting points. Here's a photo of a typical one we used.