Help in designing a rotating jib crane?

I bought a 1 Ton manual chain hoist with a trolley http://www.amenabar.net/ and I would like to make a rotating crane like this one: http://www.vestilmfg.com/products/mhequip/gantry-jibfm.htm The question is: What kind of devices do I need to make it rotate? any ideas or web links of parts... show more I bought a 1 Ton manual chain hoist with a trolley

http://www.amenabar.net/

and I would like to make a rotating crane like this one:

http://www.vestilmfg.com/products/mhequi...

The question is:

What kind of devices do I need to make it rotate?

any ideas or web links of parts suppliers are welcome
4 answers 4