====== Wheel train ======
The **wheel train** is part of the watch [[movement]], containing all of the geared wheels that drive the [[hand]]s and [[complication]]s. These gears transfer [[torque]] from the [[barrel]] to the [[escapement]] wheel.

The wheels are usually held in place by [[bridge]]s or [[cock]]s connected to a [[plate]]. High-torque wheels are usually anchored with [[jewel]]s (and sometimes [[chaton]]s) though other wheels may rest in simple holes. The [[balance wheel]] usually also has an [[anti-shock]] device to anchor its [[staff]].

The wheel train includes 

===== Going train =====
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The main gear train of the timepiece is known as the **going train**. These wheels transmit torque from the [[mainspring]] to drive two primary functions 

  - They drive the rotation of the hands and other complications
  - They power the [[balance wheel]]

The going train consists of three or four main gears or wheels 

  * The **second wheel** (Z1) turns once per hour to drive the //motion work// which turns the hour and minute hands. In traditional movements (which place the seconds in a secondary dial), this is at the center. It is called the second wheel because it is the second wheel in the gear train after the [[barrel]]. It it is often also referred to as the **center wheel**.
  * The **third wheel** (Z3) drives the [[pinion]] for the //fourth wheel// or, for clocks which lack a fourth wheel, drives the [[escapement]] wheel directly.
  * The **fourth wheel** (Z5) drives the seconds subdial and [[escapement]] wheel. It is sometimes dispensed with in modern movements, with [[central seconds]] driven by the motion work and the escapement driven by the third wheel directly. Because of its function, this is also sometimes called the **seconds wheel**, though it is easy to confuse this for the //second wheel// noted above.
  * The **escapement wheel** (E) moves one tooth at a time, kept in time by the [[escapement]]. It also powers the escapement.

===== Motion work =====
The **motion work** moves the [[hand]]s and is driven by the //second wheel// (also often called the //center wheel//). It includes a 12 1 reduction gear train to drive the hour hand from the minute hand and is often located just behind the dial.

The motion work consists of the following gears or wheels 

  * The **[[cannon pinion]]** holds the minute hand. It is usually friction fit over the center [[shaft]]
  * The **[[minute wheel]]** drives the //hour wheel//
  * The **[[hour wheel]]** fits over the [[shaft]] of the cannon pinion and holds the hour hands

===== See Also =====
  * [[Central seconds]]


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