Chapter 13 The Dual Impulse Escapement. A true innovation. | The 25th anniversary of the 9S mechanical calibers 25 years of innovation and evolution | Grand Seiko

Chapter 13

The Dual Impulse Escapement. A true innovation.

As the mainspring in a mechanical watch unwinds, its power is transmitted through the escapement to the balance, whose back-and-forth motion regulates the speed of the hands and so determines the accuracy of the watch. The basic design of the “club tooth” escapement used in most mechanical watches has remained largely unchanged over the years but several advances have been made, among which the Grand Seiko Dual Impulse Escapement is one of the most important.

Developed entirely in-house in 2020 for the Hi-Beat 36000 80 Hours Caliber 9SA5, it delivers greater energy efficiency by combining two ways of transmitting the power of the mainspring to the balance; first, the “direct impulse” which, as the name implies, transmits the power directly from the escape wheel to the balance and, second, the conventional “indirect impulse” through the pallet fork.

As a result of this innovative system, Caliber 9SA5 delivers a power reserve of 80 hours, which is truly remarkable for a 10-beat movement. The Grand Seiko Dual Impulse Escapement represents a significant advance in the design of a mechanical watch’s most critical component.