At another forum we started talking about gold center wheels on hamiltons how the later 992B made in the 1950's did not have one and the one's that did was not solid gold but gold plated.Now I was talking to some one I know and he said they were solid gold becouse it helped with the adjustment for temp.Now can any body tell me the truth solid gold or gold plated?And did it help with the adjustment for temp.

Mike, My understanding is that gold wheels in a watch train ,being a softer metal, have a smoother rolling action in the pinions which reduces friction thru the train wheels.Plus they look nicer and added value.Many higher grades have an all gold train.I don't know if all were solid gold,though.I don't know if that would have any temperature effects.I'm sure the more expert members will have a much better explanation than mine...Ted Brown.

Mike & Ted,

Welcome to IHC185!

This topic has come up before and is of special interest to me & other members who collect 992B's.

As a result of research done by several IHC185 members, the consensus seems to be that the "polished gold center wheel" that Hamilton used in early 992B's was brass, electroplated with 24K gold and polished, not solid gold.

The change to a plain brass center wheel happened somewhere between serial number C118000 and C119000, circa 1945-1946.

Here is a prior topic in our 992B Research Forum that goes into more detail about it:

https://ihc185.infopop.cc/eve/forums/a/tpc/f/254108073/m...=675107989#675107989

And in Pocket Watch Discussions:

https://ihc185.infopop.cc/eve/forums/a/tpc/f/1086047761/m/3496002012

Thanks Edward for the info I am learning here at this forum.The center wheels are made of brass
24 carrot gold plated and thanks again for that info from another post.

Gold plated center wheel and none gold center wheel

I have thought about this center wheel question as an observer of the physical question of the "rolling torque loss reduction of Wheel and pinion sets". I believe that it is almost comical to consider any miniscule improvement factor of lower rolling friction on the center wheel which is operating with at least 300 times more torque power than the escape wheel. I strongly believe that the use of Gold or Gold plating was more affectation than fact of performance enhancement. Evidently Hamilton admitted in their last days that it made little difference too.

Edward,
It was fun to look back at my post from 2002, thanks.
If a wheel or train of wheels were solid gold, it would be too soft, and wear in quick fashion.
Brian C.

Another thing, no watch company that I ever heard of used a gold center wheel or train wheels in anything other than 3/4 plate or bridge movements, where they could be seen.That tells you right there that they had little or no performance value.I'm sure if it made any difference that the 18s ultra high grade full plates like the '92 models, Hamiltons, Special Railway's, etc. would have had them.