Components – The Movement – The Bearings

BEARINGS WITH ENDSTONES

MENU

1. General Description

Small-diameter pivots, which do not experience excessive torque, are suitable for such bearings. Endstone systems require two jewels: the first is similar to a simple bearing jewel. A second flat, unpierced jewel (called an endstone) limits the vertical shake of the wheel (Figure 1).

Figure 1

Plan and section of Bearings with Endstones

Click on the thumbnail to enlarge

Figure 2

Plan and sections of Bearings with assembled Endstones(two constructions)

Click on the thumbnail to enlarge

2. Constructions

Two methods of constructing Endstone Bearing systems exist:

• In the first, and most common today, the two jewels are pressed into a single Chaton (jewel setting), which will itself be pressed or screwed into the Main plate or Bridge for which it is intended (Figure 2, lower pivot).
• The second construction is the oldest and is still used in high-quality traditional watchmaking. In this case, the Bearing jewel is pressed directly or via a Chaton (jewel setting) into the Main plate or the Bridge. The Endstone jewel, meanwhile, is pressed into the endstone plate (generally made of Steel), which is superimposed on the Bearing jewel and is screwed into the Bridge or the Main plate (Figure 2, lower pivot).

Whatever its construction, such a system involves conical pivots. Its advantage lies in the maximum reduction of friction (radial and vertical). Thus, in the horizontal position, only a tiny surface of the rounded end of the pivot is in contact with the jewel . This system also allows for limiting and controlling the height Shake (play) of the wheel with greater precision.

3. Lubrification

La construction en chaton implique de déposer l’huile sur le plat de la pierre contre-pivot à l’aide d’un pique-huile automatique (le système ne pouvant pas être ouvert)

La construction avec une plaque contre-pivot permet d’ouvrir le système, de déposer l’huile au centre de la pierre contre-pivot à l’aide d’un pique-huile simple, puis de refermer méticuleusement le système.

Dans les deux cas, on vérifiera scrupuleusement le bon dosage et le bon centrage de l’huile déposée.

4. Fields of application

Endstone bearing systems are used exclusively for escapement wheels and, formerly, for balance wheels. Since the advent of shock-resistant systems (endstone systems with shock absorber), these are systematically used for balance wheels and, more rarely, for escapement wheels.