lattice jib extensions: why?

[r8lobster]

Hello, there:

Just coming across this site today. I'm a writer trying to do some some research on basic crane design and am looking at mobile telescopic boom cranes. Have found plenty of promotional material, but not much in the way of explainers.

Can anyone tell me why you'd want to use a fixed lattice jib extension at the end of the telescopic boom? On what kind of jobs is that good for, and why?

Thanks for the help!

-- r8lobster (n00b)

 

[civilperson]

By separating the tension cable and the stick by the distance of the jib, the stick loses a dual loading of flexure and compression and feels only compression.

 

[bimr]

The jib is an extension attached to the boom point to provide added boom length for lifting specified loads. The jib may be in line with the boom or offset to various angles in the vertical plane of the boom.

A jib is most commonly a component that extends the upper/outer end of a boom and provides both extension and greater access/availability for the lift.

http://www.slideshare.net/vipinb/presentation-on-mobile-cranes

 

[chicopee]

Get a book "Cranes and Derricks" by Shapiro. An excellent reference for your edification.

 

[DRC1]

Second the recomendation on the book. Also, jibs can be offset slightly which makes handling materials in some situations easier. A common example is setting materials on a roof top. Since it is angled slightly, the crane can sit back from the building a little nad not worry about the boom contacting the building at the roof/ wall line. Because it is lattice it is light and easily carried. Generally it does not have large capacities.