Tuning Machine

The assembly found (usually) at the peghead end of a guitar or bass that serves to both secure a string and adjust the string’s tuning. The tuning machine usually consists of a shaft that passes through all or part of the peghead, and around which the string wraps, and a knob that the performer uses to turn the shaft using a gear mechanism. As the shaft turns, the string tension is tightened or loosened, raising or lowering the string’s pitch.