A Basic Watch and How it Works

This is my first post and a primer on future ones. I am going to explain a basic watch and how it functions,

A basic watch has 4 main systems. 

  1. Gear Train
  2. Winding Works
  3. Escapement
  4. Setting/motion works

 

Gear train. Made up of 5 wheels 4 pinions, this is where the the power from the mainspring is transferred to the escapement. The tooth count allows for a gear reduction that matches the needs of a watch. In most, the second/great wheel rotates once an hour and the 4th wheel rotates once a minute. The pivots on these wheels go into jewels, bushings and sometimes simply holes in the brass plates. 

 

Winding works: Turning the crown, turns the winding pinion (yellow part in red box). The winding pinion tuns the crown wheel (green) which turns the ratchet wheel (blue) which turns the mainspring arbor, the click (purple), keeps the power from backing through the previously mentioned gears.

The arbor (second picture) has a hook that grabs the hole in the mainspring, which has a tongue end, that gets "stuck" on the hook in the side of the barrel. Without power from winding, transferring through the gear train, the escapement isn't active.

 watch winding mechanism works

Escapement: The timekeeping element of a watch, the escapement, is the most complex, delicate and precise section of the watch, The power stored in the mainspring, transfers down the gear train to the escape wheel. An escapement allows the slow and regulated "escape" of power.

In (most) watches made since the late 1800s, the system to do this is the "lever escapement". There are three main components made up of 11+ parts.

The escape wheel (green), which has clubbed teeth, has power upon it, wanting to spin. The pallet fork (blue) stops the spin. The balance (second picture) swings back and forth and has a pin or roller jewel (red circle) that knocks the pallet back and forth allowing one tooth to advance. Attached to the balance is the hairspring which regulates the back and forth speed of the balance wheel. 

 

 

 

 

 Setting/motion works: Once you have a running, regulated watch, you need a way to show time and also be able to change it. This achieved with a simple and clever set of parts. The power and time keeping of the watch is put upon the great/second wheel, this is chosen because it has a lot of torque remaining from the mainspring. The pivot of the second wheel protrudes from the dial side of the main plate (left purple box). Fitted onto this pivot is the Cannon pinion (right purple box), This is a pinion that also acts as a clutch so that time can be changed without breaking teeth to move the hands.

The cannon pinion also rotates the minute wheel (dark blue) which has a pinion that rotates the hour wheel (pink second picture), this reduction takes the once an hour rotation of the cannon pinion, and makes it a once every twelve hour rotation. Now hours and Minutes.

 

As for changing the time, you have the setting works which is 5 parts, The stem (red) the Clutch (orange), Clutch lever/spring (green), the Detent/Setting lever (yellow), and the set bridge/yoke (blue, 2nd picture). This system turns the action of pulling the stem out, into sliding the clutch to engage the motion works/intermediate wheels (light blue). Then when pressed back in, the clutch engages back into the winding pinion (which engages with the crown wheel to wind the watch). The setting position is in the brown box. 

 

 

 

 

 And thats a basic watch, a beautifully designed piece of engineering that we all have an affinity for. When you understand the principles of how they work you can better understand complications and also what makes mechanical watches so special. If you have a mechanical watch that needs service or repair, please look here at my price chart and to contact me.


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  • ed zamborsky on

    I have several watches serviced by Mike. From old classics to modern marvels. Each one has been retuned to me in perfect operating condition and beautiful cosmetics. Mark is a rare diamond in the watchmaking/watch repairing world. He does what he promises in a timely fashion and he does it the first time around. I am a customer for life.


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