How the three main engine of the space shuttle work?

Answer 1

The three engines can swivel 10.5 degrees up and down and 8.5 degrees from side to side during ascent to change the direction of their thrust and steer the Shuttle as well as push. The orbiter structure is made primarily from aluminium alloy, although the engine thrust structure is made from titanium (alloy).

Answer 2

Here is a good source of information;

http://en.wikipedia.org/wiki/Space_Shuttle