All Wadokei operated with a Crownwheel and Verge Escapement. Early verge arbors were attached to horizontal foliot arms with movable weights, but later the verge arbors were developed to operate horizontaly with a pendulum at the end (acredited to Asada, 1795). Later verge arbors operated with a balance wheel and spring. Developments in escapements appeared in Japan about 75 years later than their origins in Europe.

Single Verge and Foliot

Early Wadokei escapements, from 1620 onwards, had a single verge and foliot based on the designs of the early Dutch Clocks that were gifted to Japanese Shogunates, Daimyo and Traders.

Unlike the use of foliot weights in Europe that were used to regulate constant oscillations in a day, Wadokei foliot weights required to be repositioned twice a day at dawn and dusk to compensate for the corresponding lengths of day and night. These adjustments were compounded with the changes in Seasons. The exception would be around the Spring and Autumn Equinox when the day and night hours would be the same.

Double Verge and Foliot Escapements

In 1773 the idea of operating Wadokei with a double verge and foliot was introduced. One foliot regulated the hours of daylight, whilst the other for the hours of night. Each verge arbor was engaged and disengaged with a double pair of crown wheels by a pair of arms appropriately raising and lowering each of the arbors.

At first the levers were moved by pins in two arms. Later the pins vanished and the work was done by a square cam located by a spring. Finally the lifting was done by two triangular cams and the spring eliminated, the weight of the arm resting on one side of the triangles being enough to stop it turning. A pin on the strike countwheel rotated the camshaft 60 degrees on the strike of 6 at dawn and dusk.

This arrangement significantly simplified the adjustment of foliot weights as these only required to be adjusted at 14 day intervals to take account of the Seasons.