The major component of a mechanical movement is the mainspring, a special gradually unwinding spring responsible for transmission of energy.  The oscillator of a  mechanical movement is the balance wheel, a small wheel moving very quickly.  In most watches produced at present day the balance wheel oscillates 28, 800 times per hour.  One more important component of the mechanical movement is the balance spring, also called the hairspring, a tiny delicate spring necessary for controlling oscillations of the balance wheel.  Mechanical movements are divided into two major groups – automatic, also called self-winding, and manual-wind, also known as hand-wound or wind-up.  More on that next time or click this link: Watches Infoniac.com.