hammer drill...?

[joko]

can anyone tell me what a hammer drill does?

i realise it is a drill, but what is the hammer part?

does it have an attachment that goes back and forth, rather than spins, like one of those large road drills, for breaking concrete ?

or is it that it punches screws in?

thanks

[mibn2cweus]

click here

I've never seen one used for screws.

[Pete,A]

The hammer part of a drill vibrates the drill bit ,to make easy work of drilling masonary. The drill bit vibrates , moving in and out, as well as rotating, having the effect of hitting the the drill bit with a hammer as it rotates.