Dual time

Watch 101 - What is Dual Time

Watch 101 - What is Dual Time

Dual time is a feature that some technical watches have. Dual time watches indicate time in two different time zones. It contains two hour hands in its dial. This is a common feature that travelers look for in a timepiece. There is an option for the wearer to set the watch’s default or home time zone. The hand that indicates the home time zone is more visible than the second time zone, referred to as the GMT or UTC hand. Usually, the second hour hand displays 24 hour data as compared to the home hand that indicates only 12 hours. This will help the wearer to differentiate the home time from the second time zone.

To understand better how dual time function works, you should have an idea how the motion works operate. The reducing gear train that is driven by the center wheel rotates every hour. This explains why the minutes and hours hands rotate. There is a cannon pinion that is connected to the wheel arbor that sets the ratio of the minute wheel at 1:3. On the other hand, the hour wheel ratio is set at 1:4. This will result to a total of 1:12 ratio therefore driving the hour hand. The hour hand and the hour wheel are interconnected that results to the indication of the appropriate time.

There are two primary differences in a dual time watch and the standard hours and minutes watch.

First, the second hour hand must indicate 24 hours. To achieve this, two additional wheels are added to the motion works. To achieve the ratio f 1:8, the second minute wheel that is positioned co-axially drives the 24 hour wheel. The cannon pinion will also achieve the ratio f 1:3 combining it to the 1:8 by the minute wheel to the 24 hour wheel will overall result to 1:24 ratio that will help significantly for the 24 hour hand to function.

Another factor that sets dual time watch from the regular watch is that this one is relying solely in the hour increments. There is a separate and distinct hour wheel post that fits only the hour hand. Its 12 teeth are positioned in the star wheel at the post’s outer edge.  These teeth are responsible with the change of hours when 60 minutes passes.

Featured Image Credit: Global Rakuten

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