Valves  
Valves-1
Description:
Modern Trumpets have three piston valves. Each valve increases the length of tubing when engaged, thereby lowering the trumpet pitch. The first valve lowers the instrument's pitch by a whole step (2 semitones), the second valve by a half step (1 semitone), and the third valve by one-and-a-half steps (3 semitones). Used separately and in combination these valves make the instrument fully chromatic.