Bass Drum Pedal 
bass-drum-pedal
Description:
A Bass Drum pedal operates when a "footplate" is pressed to pull a chain, belt, or metal "drive" mechanism downward, bringing a "beater" or mallet attached to a "shaft" forward into the drumhead. The pedal and beater system is mounted in a metal frame and a "tension unit" controls the amount of pressure needed to strike and the amount of recoil upon release.