Lubrication of crown wheel

[ifibrin]

Just curious, but why is the crown wheel only lubricated at the “post” or the part where it rotates around, but not underneath on the entire part it slides around on the barrel bridge?

The same question goes for the wheels in the motion work that are in the motion work; why are they only lubricated at the post? I can rationalize for these since they turn so slowly and are not under a lot of torque or pressure...

[HSL]

3 hours ago, ifibrin said:

You don’t need to lubricate the teeth of the ratchet or crown wheel because you already lubricated the winding pinion with grease , one should use just enough (very little) lubrication on a movement. The small amount of grease on the winding pinion will transfer in a good enough amount to both of them.

Underneath the crown wheel you have a small raised part, since you dont get so much force on this one most manufacturers don't think you need to lubricate that part since the wear of it will be minimal during the watches calculated lifetime. the post which  takes up more force and is at the same time thinner is lubricated because you don't want it to wear down since you screw down the ratchet wheel in it.
The raised part is a design feature to let the teeths of the crown wheel to expand a bit from wear without starting to grind on the movement.

Otherwise, one tends to lubricate where the largest stress occurs this is often by the posts. The forces on the drive train teeth on the wheels is quite moderate and the risk you get dirt stuck in them is greater if you have lubrication on them. here you just need to lubricate the jewels wich like the posts take up the most of the forces.

 

 

Edited June 24, 2021 by HSL

[Klassiker]

Put simply, the lubrication is there to separate parts sliding over one-another under pressure. If you don't have pressure, like between the crown-wheel and bridge, then there's no need for lubrication. The same goes for the wheels in the motion works. Although the forces are lower, what thrust there is is radial, against the central post.

[ifibrin]

Actually, I meant why was only the inner edge of the crown wheel lubricated, on the side contacting the crown wheel core, and not on the side sliding on the barrel bridge too?

[xyzzy]

It's like @Klassiker said, the crown wheel is being pushed to the side, not up and down.  It's the vertical edge of the ridge in the crown wheel that resists this force.  Otherwise when you turn the crown it would just push the crown wheel off to the side.  It would pivot about the tooth engaged with the ratchet wheel.

[ifibrin]

5 minutes ago, xyzzy said:

It's like @Klassiker said, the crown wheel is being pushed to the side, not up and down.  It's the vertical edge of the ridge in the crown wheel that resists this force.  Otherwise when you turn the crown it would just push the crown wheel off to the side.  It would pivot about the tooth engaged with the ratchet wheel.

Oh... This makes what everyone else said clearer!