In the field of pocket watches, they can often be heard to mention the two escapement mechanisms common in the big eight watches: ‘seconds and a minute and a half seconds’, ‘seconds and a minute’ is ‘beating seconds’ Meaning, the second hand jumps by one second; ‘second and half minutes’ means ‘shoot half a second’, the second hand jumps by half a second, but according to my actual measurement, it is not a real half-second, run for one minute, the second hand jumps 140 times, that is Jump for 3/7 seconds, slightly less than half a second. The official Chinese name of ‘second and half minutes’ is ‘duplex wheel escapement’ and English name is Duplex Escapement, commonly known as ‘tangle escapement’, because the static teeth of the compound wheel are slender triangular tines. The double wheel escapement is a type of non-free escapement. It was invented by Baptiste Dutertre around 1730 AD. It was improved by the famous French watchmaker Pierre Le Roy in 1759 and became a type of watch Escapement.
The compound wheel escapement consists of two components: a compound wheel and a balance wheel. The balance wheel assembly is composed of the balance wheel 1, the impacted column 2, the grooved cylinder 3, etc .; the compound wheel is composed of the stationary teeth 4, the impact teeth 5, etc. The impact teeth were originally designed as another gear stacked on the stationary gear. That is, the compound wheel was originally called the ‘compound wheel escapement’ because the two gears are superimposed on each other. Later it was improved to the status quo. The compound wheel has steel or copper products. Copper products are commonly found in British clocks and watches.
When the balance wheel swings counterclockwise, the A stationary tooth slides out of the groove of the grooved cylinder 3, and the compound wheel rotates clockwise under the driving force of the spring through the gear. The impact teeth 5 of the compound wheel impact the balance wheel. The strut 2 (a ‘beep’ sound is emitted at this time), the balance wheel gains power to maintain swing.
When the stationary tooth B impacts the impacted column, after the stationary tooth A slides out of the grooved cylinder, the stationary tooth B rotates clockwise by a certain angle, and collides with the grooved cylinder to stop (at this time, a “click” sound is issued. ), After the balance wheel swings into place, it rebounds under the action of the hairspring and swings clockwise.
After the balance wheel swings clockwise into position, the balance wheel returns to counterclockwise swing under the rebound of the balance spring. When the B stationary tooth enters the groove of the grooved cylinder, it completes a cycle of movement. The compound wheel escapement oscillates back and forth once on the balance wheel, and then the power is transmitted from the compound wheel to the balance wheel once. Because the two sounds of ‘click’ and ‘click’ are separated for a short time, the sound heard is similar to ‘嚓 — 嚓-嚓’ — ‘. Duplex wheel escapement is commonly found in big eight watches and other simple function pocket watches of the same period. It is also found in two-minute or even three-minute watches of the same period. Of course, the two-question and three-minute watches with compound wheel escapement are combined. It is rare and is a rare treasure. Duplex wheel escapement is also commonly found in clocks. It is easier to see it appear on our ‘national treasure’-Su Zhong.
It is worth mentioning that, in order to reduce friction (the relative sliding friction between the stationary tooth and the grooved cylinder), the advanced method of the grooved cylinder is made of ruby. In the Chinese market, eight regular enamel watches and It is easier to see in the gold case pocket watch in the non-Chinese market, but it is difficult to find traces in the eight-piece silver case, which was a large commodity in the Chinese market at that time. Generally, cheap and easy-to-make steel products are used. I have encountered a large eight-piece silver watch with a silver case with a double-wheel escapement made of a rubbed cylinder with grooves. Please cherish it. Everyone should pay attention when collecting. (Text / picture watch home think time)