Another word-ological victim of guitarists’ tendency to refer to their guitar’s vibrato system as a “tremolo” system. Tremolo springs (vibrato springs) are used to counter-balance the pull of the strings. The springs balance the bridge or tailpiece of the system so that the guitar can be played normally, and provide tension so that the bridge or tailpiece returns to its balanced resting position after the vibrato system is used to raise or lower the pitch of the strings.
With a surface-mount tailpiece system, such as a Bigsby, the spring is inserted between the vibrato bar and the tailpiece. In an internally mounted system, such as the standard Stratocaster tremolo or a locking tremolo system, such as a Floyd Rose, the spring is located inside a body cavity in the back of the guitar. It is attached to a moving block that is integral to the bridge on one end and a “claw” screwed into the guitar’s back on the other.