Chr. Ward C9 harrison jumping hour mk I, Руководство пользователя

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7
Chris Explains...
“The Jumping Hour mechanism all operates between the base movement and an hour disc. In the
case of the C9 Jumping Hour the base movement is an ETA 2824-2 and the addition of the module
adds an extra 2.4mm to the height of the movement.
The hour disc is held by two screws onto a central star wheel which has 12 teeth (see page 9).
On the central minute wheel is directly mounted a cam which therefore makes one rotation every
hour. When the rotary cam turns it picks up a lever once per hour and with pressure exerted upon
it form a spring forces the star wheel to move 30° or a one hour jump (360
÷
12).
The hour disc therefore moves on 30° also under the main dial. The main dial has an aperture cut
out at 12 o’clock to display the hour underneath. The cam solution means that immediately after
the hour has jumped the cam starts to pick up the lever again, gradually moving it closer to the star
wheel ready for the next jump. The beauty of this is that the power consumption is consistent over
the 60 minutes giving a much higher degree of accuracy than a lot of other jumping hour complications
in the market, which usually will only use power in the last 15 minutes, and therefore during the
course of an hour there is terrific variation in both power consumption and therefore accuracy.
It also means that a much more stable amplitude is achieved over the hour and in the long term is
much better for the life of the watch. Regulation is also that much easier due to the consistent power
consumption.