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  • Chronograph
    An instrument which measures accurate divisions in time, the most basic of which is commonly(...)
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    The Balance Wheel forms part of an assembly which functions to regulate the speed at which the(...)
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    A gear train is a collection of wheels and pinions with varying amounts of teeth and pinion(...)

Train Of Wheels

The train of wheels is a group of gears within a clock or watch movement which provides a specific ratio in order to complete it’s function. This is sometimes referred to simply as The Train.

There can be several gear trains depending on the design of the movement.

The most common gear train would the that which is driven directly by the power source to deliver it’s energy to the watch escapement. This is the primary gear train and is actually referred to as the “Gear Train” or “Train of Wheels” by most horologists.

We cover the train in full detail in the Watch Repair Course. In particular, level 1 discusses all the basic watch components and how they interact with each other in order for a movement to function. Level 3 aids you in finding faults within the watch movement including the train of wheels.

Another common gear train within a clock or watch movement is known as the motion work. This will normally be driven directly by the train. Through it’s ratio of gearing the motion works will provide for the display of time.

But whenever the train is mentioned by horologists, they are usually referring to the gear train which serves energy to the escapement and this is certainly true of

Train Of Wheels
Train Of Wheels

The train of wheels of a typical watch or clock are made up of…

  • The Great Wheel (Or mainspring Barrel)
  • The Centre Wheel
  • The Third Wheel
  • The Fourth Wheel
  • The Escape Wheel (Also forms part of the escapement)
Wheel_train (Wikipedia)

In horology, a wheel train (or just train) is the gear train of a mechanical watch or clock. Although the term is used for other types of gear trains, the long history of mechanical timepieces has created a traditional terminology for their gear trains which is not used in other applications of gears.

Watch movements are very standardized, and the wheel trains of most watches have the same parts. The wheel trains of clocks are a little more varied, with different numbers of wheels depending on the type of clock and how many hours the clock runs between windings (the "going"). However, the wheel trains of clocks and watches share the same terminology, and are similar enough that they can be described together. The large gears in timepieces are generally called wheels, the smaller gears they mesh with (large to small, large to small) are called pinions, and the shafts that the wheels and pinions are mounted on are called arbors. The wheels are mounted between the plates of the movement, with the pivots rotating in holes in the plates. The pivot holes have semicircular depressions around them, called oil cups, to hold the oil in contact with the shaft by capillary action. There are several wheel trains in a typical clock or watch.

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Iman Roder
3 months ago

I’m assembling a unitas 6498 (while following your course) and when I place the bridge over the train wheels they no longer spin freely once I screw it down fully as they had before…I keep taking it apart and reassembling it, but the same thing happens. What am I doing wrong, please help.