The photographs above show the same pocket watch wheel viewed from above and from the side, allowing the relationship between the wheel, outer teeth, pinion, arbor, and pivots to be seen clearly.

Pocket watch wheels are the means through which energy is moved around inside the pocket watch mechanism. The energy comes from the mainspring that you wind up manually either by using the crown to turn the stem, or by using a key to wind the mainspring directly.  The clicking that you hear when you are winding your watch is caused by a component called the “ratchet click” which, by virtue of a spring, bounces off of the teeth of the winding wheel when it turns in the direction to wind the mainspring; but then locks the winding wheel in place so that the energy that you have just wound into the mainspring stays locked in the mainspring until it is released into the pocket watch wheels; so that the pocket watch hands will move at a regulated rate of speed allowing us to use it to know what the time of day is.

You will encounter direct or indirect mention of the components of the pocket watch wheels in the many conversations about pocket watch specifications. Aside from the wheel structure itself, there are really only two general types of components that make a pocket watch wheel function the way that it does. The first type is tooth-like structures, and the other type is axel-like structures. Pocket watch wheels have teeth around their perimeter.  They also have teeth on a pinion located at the center of the wheel.

Both sets of tooth-like structures are riding in unison on the second type of structure, the axel-like structure, the arbor. The arbors provide all of the wheels with stable placement between the top plate and the pillar plate, between which they each engage either a neighboring wheel or a regulator component. The arbor is a large comparatively sturdy structure. At either end of the arbor is a smaller specially shaped portion of the arbor, the pivot, that penetrates the top plate or the pillar plate and rides either within a hole in a man-made jewel or a hole (bushing) directly in the metal plate itself. The pivot is shaped and polished to provide less friction between itself and the jewel or the bushing.

Ideally the pivots at both ends of the arbor are riding in the same type of environment, both in a jewel or both in a metal bushing so that wear occurs evenly; but this is not always the case. Several models of Seth Thomas pocket watches jewel the top plate holes; but not the pillar plate holes in their eleven jewel versions. I have a hard time judging the company very harshly about this; after all, a high percentage of all Seth Thomas pocket watches are found to be keeping good time after hundreds of years.