Johann Heinrich Moser

A world-first from H. Moser & Cie.
The world’s first-ever interchangeable escapement module in a wristwatch
Longevity and ease of servicing are features which the development engineers at Moser have
placed right at the top of their specification. They have accordingly pondered about how the
mechanical heart, the pacemaker of a watch, might be improved. They started by replacing the
index system on the balance wheel used for timing with traditional weight compensation
screws made of solid gold on the balance wheel ring. No easy feat, considering that the task at
hand was to manufacture screws with a precision thread of 0.35 mm in diameter. However,
the resulting advantage was worth the effort: the balance wheel beats more evenly, the
escapement is less susceptible to shocks, and the positional dependency of the watch is
reduced.
If a watch movement is cleaned during servicing, in order to remove the abrasion products
caused by friction, all the parts must be dismantled, washed, reassembled and oiled. This also
applies to the component parts of the escapement, which must then be retimed from the
beginning: this is a meticulous and, above all, time-consuming procedure. Here, too, a novel
solution was found at Moser. The complete escapement assembly is mounted on a separate
plate, for the first time in a wristwatch, and is only connected to the rest of the movement via
the escape wheel drive. This means that the assembly is completely interchangeable by
releasing only two screws. It is removed in the course of servicing and replaced by an
equivalent escapement assembly as a service exchange item. The assembly is then cleaned
and retimed, but only by specialists at Moser. The time spent in the service department by a
Moser watch can be reduced considerably in this way, and the accuracy of the timing can be
increased.