Roseba 55

Description

Roseba, one of the many swiss manufacturers of pin lever movements, which flew a bit under the radar, made this 10 1/2 ligne pin lever movement with a Roskopf-type construction, which stands out because of its odd position of the balance cock.

In the version shown here, 17 jewels were used, all bearings contain rubies, but unfortunately, there are also competely useless blind jewels on the dial side.

As usual for a Roskopf type movement, also the Roseba 55 has got on top of the mainspring barrel a double wheel, which drives both hands at the same time. This wheel is attached to the mainspring barrel with a slipping clutch.

The large mainspring barrel overlaps the center of the movement. It is followed by the large driving wheel, seconds wheel and escape wheel. The seconds wheel indirectly drives by its outer teeth the outer teeth of the center seconds wheel.

The empty bearing on 6 o’clock is interesing, maybe it is a preparation for a decentral seconds indication on another version of the movement.

A simple, non shock-protected anular balance is used, which is beared under a clock, which is mounted near the center of the large movement plate. This is a pretty unusual construction.

You can see, how the lower wheel of the mainspring barrel drives the cannon pinion.

The two cap jewels at positions 7 and 8 o’clock are weird, because they don’t have any function at all, since below them, there are no bearings. So, their only purpose was, to achive the “magical” number of 17 jewels, which should indicate a good quality movement.

The hour wheel is driven by the upper wheel of the double wheel on top of the mainspring barrel. It also drives the date switching wheel, which makes one revolution every 24 hours.

The calendar mechanism is pretty simple, the date switching wheel engages with the internal sprocket of the date disc. A spring takes care, that the date disc properly locks after each switching process.

Technical data

Usage gallery