Watch Terminology Dictionary

A type of clutch mechanism for mechanical chronographs. Generally, the chronograph is operated by pressing the clutch from above against the fourth wheel, which rotates once per minute. Although it requires vertical space and does not have the appearance of a mechanical chronograph, it does not cause the hands to jump when the chronograph is running, is less likely to lose amplitude, and saves space. For this reason, the majority of automatic chronographs designed since the 1980s use horizontal clutches. Typical examples include Rolex's caliber 4130 and Breitling's 01.