A ROBUST AND FORWARD-LOOKING SOLUTION.

The L034.1 manufacture movement in the LANGE 31 is a true power pack. In a space with a diameter of 37.3 millimetres and a height of 9.6 millimetres, it stores the energy needed to keep running non-stop for 31 days. Two crucial questions had to be answered by Lange’s cali-bre engineers: how can so much energy be stored in a movement? And, just as important: how can this energy be delivered in a con-trolled manner?

3700 MILLIMETRES OF SPRING LENGTH.

The energy storage function is handled by the large twin mainspring barrel – two stacked spring barrels, in fact, with an inside diameter of 25 millimetres. They contain the two mainsprings, each of which is 1,850 millimetres long – five to ten times as long as the springs of conventional mechanical wristwatches. When fully wound, their combined energy is equivalent to more than 3 joules.

CONTROLLED DELIVERY OF THE ENORMOUS POWER.

The torque delivered by the mainspring barrel has its maximum when the spring is fully wound and then declines perceptibly as the spring relaxes. This changes the rate parameters of the movement, espe-cially in watches with large power reserve values. To eliminate this unwanted effect in the LANGE 31, the manufactory’s master watch-makers integrated a constant-force escapement.

The main element of this mechanism is a pretensioned spiral spring that is quickly retightened on the fly at intervals of ten seconds.
During the ten seconds that follow, the energy stored in the spring is delivered to the going train in a controlled manner. The torque output
is virtually constant and powers the watch uniformly throughout 31 days.