Useage of different turning tools

[Dorian]

Hi - I'm just learning to use a lathe and have bought a set of turning tools that include the following (I found the descriptions on the net):

• ISO 2: Left- and right-oriented cranked turning and facing tools
• ISO 6: Cranked knife tool
• ISO 7: Parting tool
• ISO 8: Boring bar

It's all pretty obvious to me which tool to use when, except for the knife tool. Does anyone know what type of cuts it's supposed to be used for? And why are they called "cranked" tools?

Cheers
Dorian