CONSTANT-FORCE ESCAPEMENT

CONSTANT POWER

Movement L043.9 of the ZEITWERK HONEYGOLD "Lumen"

The purpose of a constant-force escapement in a mechanical watch is to provide the escapement with a consistent flow of power, regardless of whether the watch is fully wound or nearly unwound.

THE CONSTANT-FORCE ESCAPEMENT MECHANISM

WITH THE PERSEVERANCE OF A MARATHON RUNNER

With two strong springs, the twin mainspring barrel of the RICHARD LANGE PERPETUAL CALENDAR “Terraluna” provides a power reserve of 14 days. The LANGE 31 tops this with 31 days. Like a marathoner, this constant-force escapement consumes a considerable amount of energy and – even more importantly – must deliver its power in doses.

If fully wound, the torque delivered by this high-energy mainspring barrel would be much too high to be transferred directly to the escapement. And if its torque declines when it approaches the unwound state, the accuracy of the watch would deteriorate. To keep the rate of the watch stable for the entire power-reserve period, a patented constant-force escapement is integrated between the twin mainspring barrel and the escapement of both watches.

It causes the twin mainspring barrel (1) to produce a small amount of energy every ten seconds. This energy re-tensions the remontoir spring (2) by an angle of 60 degrees. It corresponds to precisely the amount of energy that it will transmit to the escape wheel (3), the lever (4) and the balance spring (5) within the next ten seconds.

Since the remontoir spring always releases exactly the same amount of energy, the watch is powered with the same torque every day. The result is a constant amplitude and thus an especially high degree of rate accuracy. The remontoir spring of the constant-force escapement and the balance spring are both manufactured in-house and can thus be optimally paired with the movement.

LIKE THE POUNCE OF A PUMA

In the ZEITWERK models, the constant-force escapement not only supplies the escapement with a steady flow of power, but it also generates the switching impulses needed to advance the jumping numerals. Like a puma preparing to pounce, the constant-force escapement must deliver a strong burst of energy.

It is designed to execute a re-tensioning cycle precisely every 60 seconds. For a brief moment, the full torque of the mainspring barrel is released for re-tensioning. Instantaneously, this burst of power is used to switch the numeral discs.

THE ZEITWERK FAMILY

THE ZEITWERK FAMILY

THE NEW ERA OF THE MECHANICAL WATCH

When they developed the ZEITWERK, Lange's engineers questioned everything – except the mechanical paradigm.

LIKE A HOVERING HUMMINGBIRD

In the RICHARD LANGE JUMPING SECONDS, the constant-force escapement and the jumping seconds mechanism are assigned to separate but firmly interconnect wheel trains. Like a hummingbird, which needs to beat its wings at high frequencies to hover in mid-air, the constant-force escapement must perform many fast-paced switching steps with one-second precision.

The mainspring barrel is briefly set free once a second. In the process, it moves the seconds hand forward by one second and incrementally tensions the spring of the constant-force escapement. All the while, the watch runs very precisely thanks to a constant delivery of force.

COMPLICATIONS

OUTSIZE DATE
OUTSIZE DATE
The A. Lange & Söhne outsize date enables a date display with digits around three times as large as those in watches of comparable dimensions.
CHRONOGRAPH
CHRONOGRAPH
Chronographs and their manufacture movements have been flagship products of A. Lange & Söhne since 1999.
CALENDAR FUNCTION
CALENDAR FUNCTION
Lange models incorporate either annual calendars or perpetual calendars.
MOON-PHASE DISPLAY
MOON-PHASE DISPLAY
Most of our moon-phase displays reproduce the moon’s orbit with a precision of 99.998 per cent.
POWER-RESERVE INDICATOR
POWER-RESERVE INDICATOR
The UP/DOWN display reminds the owner to rewind the watch before it stops running.
TOURBILLON WATCHES
TOURBILLON WATCHES
The tourbillon improves the rate accuracy of a mechanical timepiece by overcoming the influence of gravity on the running of a watch.
THE FUSÉE-AND-CHAIN TRANSMISSION
THE FUSÉE-AND-CHAIN TRANSMISSION
The fusée-and-chain transmission is one of the most effective complications when it comes to increasing the rate accuracy of a mechanical watch.
CONSTANT-FORCE ESCAPEMENT
CONSTANT-FORCE ESCAPEMENT
The purpose of a constant-force escapement in a mechanical watch is to provide the escapement with a consistent flow of power, regardless of whether the watch is fully wound or nearly unwound.
CHIMING MECHANISM
CHIMING MECHANISM
Chiming mechanisms make it possible to hear the time.

EXPLORE FURTHER

LANGE BALANCE SPRING
LANGE BALANCE SPRING
Crafting a balance spring is one of the most complicated tasks in precision watchmaking, one that only very few manufactories master.
JUMPING NUMERALS MECHANISM
JUMPING NUMERALS MECHANISM
The ZEITWERK is a mechanically driven digital-display watch.
MANUAL WATCHES
MANUAL WATCHES
A manually wound mechanical watch must be regularly rewound with the crown. This provides the mainspring barrel with fresh energy.

HOW CAN WE BE OF SERVICE?

Whether you are in search of a specific model, have questions out of interest or need a service request for your timepiece – we are delighted to help you. We are at your service by phone, email or in one of our boutiques. 

The A. Lange & Söhne salon in Zurich