EB 8461-74

Description

In 1974, the swiss Ebauches Bettlach released the EB 8461-74.

The biggest differences to the predecessor EB 8461 are a simpler constructed, flat, balance wheel cock and the use of a pin instead of a screw for securing the setting lever. To release the crown, you have to directly lift the setting lever with the smallest screw driver!

Another difference to the predecessor is, that below the balance wheel, two holes are missing.

The gear train is typical for EB, it uses very few space and consists of second and third wheel, followed by the directly driven center second wheel and finally the escapement wheel. The second wheel is driven by the mainspring, and there’s no center minute wheel.

The yoke winding system is not located on the dial side, but on the base plate - odd but typical for EB.

The balance wheel is beared in two Novodiac shock protections, which don’t use any rubies but only metal bushings and caps. It beats with 18000 A/h and regulates a pin lever movement. As common on EB movements, the balance wheel is flat and light and also the hairspring is much weaker than on other movements. If don’t care, it will bend on the slightest occasion.

The only jewel of this movement is the ellipse of the balance wheel, which interconnects with the fork of the (pin-)lever.

The ratchet has got an oddity: It is located on the inner side of the gear train bridge and is a very simple construction, consisting only of the crown wheel and a U-shaped spring, which (hopefully) blocks it when it wants to turn backwards.

On the EB 8461-74, you see its inheritance from Roskopf movements, since also on this movements, the hands (only the minute wheel) is driven by a loosely coupled third gear on top of the mainspring barrel - the top gear on the photo above.

Unlike on real Roskopf movements, the hour wheel is not driven by the mainspring, but by a normal exchanger wheel, which is driven by the cannon pinion wheel on the dial side.

Technical data

Usage gallery