Valjoux 55

History: Manual-wind chronograph rattrapante, 60s, 30min, pillar wheel, split second: crown pusher, sub second. Balance staff U1543, Stem W1728, Mainspring / battery 1.50 x 15.5 x 0.20mm

In 1945, Valjoux's answer to the split-seconds function in Venus movements was the Valjoux 55 VBR. Note that the "V" in VBR stands for Valjoux, and the "R" stands for Rattrapante. The basic Valjoux 55 VBR is a monopusher, with the center pusher controlling the start/stop of the chronograph and the pusher at 2 o'clock controlling the split-seconds functionality – essentially the reverse of the Venus calibers. The clamp for the center wheel is also designed slightly differently, with the column wheel being entirely visible (unlike the Venus movements). These movements were also significantly larger than their Venus counterparts, measuring at about 39 mm as compared to about 31 mm for the Venus. As a result, most of the watches cased with these movements measure upwards of 40 mm.

Manufacturer: Valjoux (for Vallée de Joux, "Joux Valley") is a Swiss manufacturer of mechanical watch movements. It is known primarily for chronograph ébauche movements that are used in a number of mid- to high-range mechanical watches: The company has been a part of ETA for a number of years and is a member of the Swatch Group.

Valjoux SA was founded in 1901 by the brothers John and Charles Reymond in Les Bioux and until 1929 operated under the name "Reymond Frères SA". The company specialized on chronograph movements. In 1910 it moved to a factory building maintained by the municipality of Les Bioux. The company's famous column wheel chronograph movement, Calibre 22, debuted in 1914 and lasted in production for sixty years. But it was larger than desirable for wrist watch use. The military, involved in the First World War, required reliable bracelet chronographs. Thereafter the 13-ligne chronograph Calibre 23 (diameter 29.33 mm, height 5.85 mm) was developed, which in 1916 came to the production stage and soon ticked in the wristwatches of very different manufacturers (for instance Audemars Piguet, Patek Philippe, Rolex, and Vacheron Constantin). The production lasted nearly sixty years, and until 1974 about 125,000 ebauche movements of this type were made.