DuRoWe 861 / Timex M67

Description

In the late 1950ies, DuRoWe (Laco) started the development of electromechanical wristwatch movement. 1962 their caliber 861 was launched. It was already during the peroid, when Laco/DuRoWe belonged to the U.S. Time Corporation, better known as “Timex”, and so, Timex gave that movement their own caliber number: M67.

A speciality of that movement was, that it contained a jumping second hand. Each six half-alternation, the center second hand jumps one position forth, just like we got used by quartz movements ten years later.

Since the construction contained a balance with a coil and a switching contact, it’s lifetime was pretty low, after about ten years or 2 billions of contact actions, the contacts were worn off.

The balance, which carries the coil, is beared in two inhouse Duro-Swing shock protections. Below the balance, on the dial side, the permanent magnet is located, which attracts and pushes away the coil.

On the lower side of the balance, there’s the ellipse, which actively drives the escape wheel. On the upper side of the balance, there’s another ellipse, this time made of metal, which engages with the electric contact spring and powers the coil.

Since this movement has got no mainspring, there’s no conventional crown neccessiary. Instead of it, it has got a push/pull crown on the back of the case, which engages with the hand settings mechanism, when it’s pulled out and also stops the balance. At 8 o’clock, you can see the crown setting wheel.

Timegrapher result

Except for the one exceptional value in position “dial down”, the position in which the movement was regulated, the deviation rates are impressively constant. Here you can see very clearly what it means when the balance is driven actively, by electricity, to oscillate, and not passively by power transmission from the barrel to the lever.