H. Moser & Cie., while under the aegis of Dr Jürgen Lange, started an important partnership with Andreas Strehler.
One of the projects for H. Moser & Cie. was the double-pull crown, an ingenious time-setting mechanism. The crown is fully pulled out a first time to set the date and only when pulled out a second time in full, the time can be set; thus avoiding the accidental readjustment of the correct time.
One of the highlights of Andreas Strehler’s work for H. Moser & Cie. is certainly the Perpetual 1. Many watch collectors still associate Andreas Strehler with this watch.
The Perpetual 1 is complex and yet purist perpetual calendar. The hour markers are used to display the months and the leap years are indicated on the back of the watch which gives a clear and uncluttered dial. The only indication on the dial beside time and date is the power reserve.
The big date is patented construction by Andreas Strehler. It works by using two rings, one on top of the other. The upper ring indicates the dates from 1 to 15, the lower ring the dates from 16 to 31. The upper ring has a window between 15 and 1 to display the values from 16 to 31 on the lower ring. Both rings with their inner toothing are transported by the same wheel. The two rings have a breach in their toothing when they are required to stand still. When this period is over, the moving ring takes the ring standing still along a few degrees to engage it again with the transporting gear wheel.
This date mechanism is designed to switch directly from the last day of each month to the first day of the next month, bypassing the dates in between. Normally, in perpetual calendars, this is a slow operation taking several hours.
The Perpetual 1 has a power of reserve of seven days provided by serial twin barrels. The escapement module is a design of Andreas Strehler and it has been patented with Andreas Strehler and Dr Jürgen Lange as inventors.
The whole escapement module can be unscrewed and removed from the watch as a single unit. This is one of the three elements making up the patent.
If the watchmaker should forget to unwind the mainspring before removing the escapement module, Andreas Strehler has built in a security locking mechanism to prevent fatal damage to the movement. This safety mechanism blocks the gear train and prevents the mainspring from suddenly discharging its energy. It is the second patented elements of this escapement.
The third element of the patent is the so-called Dragon Lever which adjusts the banking of the anchor.
The rights to this escapement are owned by Precision Engineering AG who offers this escapement also to third parties. Examples for the use of this escapement are Armin Strom, Laurent Ferrier and many others.
In the context of this escapement, Andreas Strehler also designed the Straumann double hairspring for H. Moser & Cie. This system was first used for the watch Henry and is now being used in many H. Moser & Cie. watches. Technically, the Straumann double hairspring is an arrangement in which two identical hairsprings are placed one on top of the other, the second rotated by 180° in relation to the first. In this design, the two hairsprings compensate each other’s gravitation error. The term Straumann dates back to the inventor of Nivarox, the metal alloy invented by Reinhard Straumann which is still used for hairsprings. This alloy does not vary with changing temperatures and does not oxidize. In German this means: Nichtvariabeloxydfest. H. Mo-ser & Cie.’s engineering arm, Precision Engineering AG, holds the intellectual property rights in the Straumann name so that this name was used for the escapement.
Another development for H. Moser & Cie. was the Perpetual Moon, a continuously moving phase of the moon with a precision of 1’000 years. The construction works slightly different from the one used by Andreas Strehler in his own watches.