CENTRE WHEEL
Centre wheel is one of the three moving parts in the gear train of a mechanical watch. It is located at the beginning of the gear train between the barrel and the third wheel.
The center wheel is usually located in the center of the movement and makes one revolution in 60 minutes. On its axis will be able to be fixed the cannon-pinion which will be able to receive the hand of the minutes. The wheel closest to the barrel is also the largest of the three wheels of the movement.
In a traditional movement it is easily located because it is in the center of the movement. From the movement side it will turn counter-clockwise. From the dial side it will turn clockwise.
Although often called a center wheel, it is actually a mobile composed of two parts, a wheel generally made of brass and a pinion and its pivots made of steel.