Editing Machine head (section)

===Locking tuners===
The term "locking tuners" has two meanings. Presently, it refers to some sort of mechanism in the string peg (usually a cam or screw) that locks the string in place, preventing slippage. With the popular increase of extreme [[Vibrato systems for guitar|vibrato-arm]] usage in the 1980s, several manufacturers introduced a modified design, commonly called ''locking machine heads'', where the individual tuner has an additional mechanism to lock the string in place and stabilize tuning, primarily intended for musicians who make regular use of the vibrato. Some designs increase string breakage at the point they grip the string.

The term "locking" is much older, possibly originating with Grover, and refers to an "anti-[[Backlash (engineering)|backlash]]" design of the gears, which greatly reduced the slippage of the basic [[Gear#Worm|worm-and-gear system]]. The gear's teeth are shaped to lock into those of the worm, with the string tension insufficient to overcome the friction between the gears. Such a design is called '''self-locking'''. Grover Rotomatics and similar designs from other manufacturers are rightly called "locking tuners".