Mechanical principles › How the mechanical Movement works

THE MOTION WORK

MENU

Figure 1: Exploded view and (accelerated) kinematics of the motion work

Click on the animation to enlarge it

Figure 2: Diagram of a motion work (with hands)

Click on the thumbnail to enlarge it

1. History

Until the 17^th century, most clocks and watches had only one hour Hand. The relative accuracy of clocks and watches, as well as the technical knowledge of the time, justify the absence of a minute hand.

The first minute hands were displayed separately on a Counter distinct from that of the hours. In the middle of the 17th century, the English Horologist (watchmaker) Daniel Quare is credited with inventing a mechanism capable of displaying hours and minutes at the center of the Dial, on the same Axis, by superimposing the wheels carrying and driving the two Hands. The Motion work was born and would see no further significant advances.

2. General description

Its role is to distribute the hour and minute information to their respective Hands and to allow their correction by the time-setting mechanism

The Motion work consists of:

1. The Cannon pinion
2. The Minute wheel (motion work)
3. The Hour wheel

Click on the thumbnail to enlarge it

3. Operation

The Cannon pinion is driven by the upper pivot of the Center wheel, which makes one revolution per hour. The Cannon pinion directly carries the minute Hand and also makes one revolution per hour.

The teeth of the Cannon pinion mesh with the teeth of the minute wheel plate, to which the minute pinion is attached. The minute pinion meshes with the teeth of the Hour wheel, which is superimposed on the Cannon pinion and carries the hour Hand. The gearing ratio of the Minute wheel is calculated so that the Hour wheel turns 12 times more slowly than the Cannon pinion and thus makes one revolution in 12 h. This is therefore a reduction Train.

When setting the time, the setting Train drives the Minute wheel. The friction that links the Cannon pinion to the upper pivot of the Center wheel makes it possible to turn the Cannon pinion-Minute wheel-Pipe wheel assembly independently of the rest of the Movement.