====== JLC 920 ======

The **JLC 920** is an [[ultra-thin]] [[automatic]] calibre developed and produced by [[Jaeger-LeCoultre]].

===== Introduction =====
Cal. 920 is famous as the only calibre to be used by all three top watch brands, [[Patek Philippe]], [[Vacheron Constantin]] and [[Audemars Piguet]], and no others. Manufactured only as an [[ebauche movement]] by [[Jaeger-LeCoultre]], Cal. 920 was sold as the Audemars Piguet 2120/2121/2122, Patek Philippe 28-255, and Vacheron Constantin 1120/1121/1122. Although manufactured by Jaeger-LeCoultre, the 920 was never used in its own-brand watches. The rights to the design are said to have passed to Vacheron Constantin when Jaeger-LeCoultre was acquired by the [[Richemont Group]] in [[2000]], and their calibre 1120 remains in production.

The JLC 920 and derivatives are [[ultra-thin|extremely thin]], measuring just 2.45 mm with a full-sized [[central rotor]] for winding. Note that, contrary to some commenters, the Patek Philippe 28-255 did not use a [[micro rotor]]. A date module brings thickness to 3.05 mm, while date and calendar modules bring thickness to 3.40 mm. Diameter is fairly standard at 12½ [[ligne]] (26.00 mm).

Cal. 920 was introduced in [[1967]] and continues in production today, with Audemars Piguet and Vacheron Constantin still selling the movement. Patek Philippe replaced their version, Cal. 28-255, with their in-house [[PP 335]] and [[PP 310]] in the 1980's and no longer uses this movement though it took them a decade to perfect their in-house replacement. Although it is a fairly old design, it remains one of the thinnest automatic movements on the market even today, only edged out by the [[Piaget 1205P]] by 0.05 mm.

The 920 features 36 jewels and Patek Philippe's famed [[free-sprung]] [[Gyromax]] balance. Four ruby wheels support the full-diameter rotor, which runs on a beryllium rail for stability.

===== Variants =====
  * No date (2.45 mm)
    * Audemars Piguet 2120
    * Patek Philippe 28-255
    * Vacheron Constantin 1120
  * Date window (3.05 mm)
    * Audemars Piguet 2121
    * Vacheron Constantin 1121
  * Date and center seconds (3.4 mm)
    * Audemars Piguet 2122
    * Patek Philippe 28-255 C
    * Vacheron Constantin 1122
  * [[Second time zone]]
    * Vacheron Constantin 1222

===== External Links =====
  * [[http://people.timezone.com/library/horologium/horologium631686780396906210|The Most Exclusive Automatic: The Vacheron Caliber 1120]]


{{tag>Movements Automatic_movements Ultra-thin_movements Jaeger-LeCoultre_calibres}}