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Reduction gear of electronic wristwatch with stepping motor and sweep second hand

  • US 4,378,957 A
  • Filed: 04/11/1980
  • Issued: 04/05/1983
  • Est. Priority Date: 08/11/1978
  • Status: Expired due to Term
First Claim
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1. A reduction gear of an electronic wristwatch having a stepping motor and a sweep second, comprising three concentric output shafts rotating at different speeds, a first one of the shafts being provided with a bearing in the form of a supporting bush press-fitted in a bore in a wristwatch plate, said first shaft making one revolution per hour and supporting a friction wheel, the shafts being drivingly connected to one another and to a shaft of the stepping motor through gear wheels and a bridge coordinated with respect to the plate and secured thereon by threaded means, wherein the improvement comprises the first shaft freely passing through a bore provided in the supporting bush, the supporting bush being press-fitted in the bore of the plate so that a portion of said supporting bush projects from the plate towards the bridge, said shaft being prevented from unlimited axial displacement in one direction by the end face of the supporting bush and in the other direction by the end face of a gear wheel which is mounted on said first shaft with an interference fit.

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