I'm looking for a Hamilton cross reference part number for a Ball Hamilton escape pinion. The S/N of the Ball is B639XXX so that puts it about 1930. Does anyone know what Hamilton escape pinion will fit this movement?

Thanks
David

I'm not a Ball or Hamilton expert, But my understanding of the lists indicate that this particular watch is an 18S Hamilton Grade 925 which has a production date of around 1908.

If that is correct, The hamilton part number for the escape wheel and pinion is #89. This part is used in grades 924-935.

I could be WAY off on that. Any Ball experts out there

Nope - 16 size grade 999 Hamilton according to the serial number list in Townsend.

The Hamilton list may be confusing on this point because this number is positioned as if the "B" wasn't part of the serial number, but it's pretty certain they weren't still making 18 size watches in 1930, and Ball certainly wouldn't have been ordering and selling them - he sort of championed the switch to 16 size (it appears from documents that this was mostly to drum up some business rather than because they were actually any better than the 18 size watches).

Well, this is actually a 16s. I measured a 992 and a 992b escape wheel pinion, and they are both longer than the one required by the 16s ball hamilton!

Harvey,

Thanks for clearing that up. I don't know how to read those ball SN lists

At a 30's production I would have thought that a 992 or 992E escape wheel and pinion (Part #366) would have been the one. But David indicates that it is not.

Does anyone know what grade Hamilton we are looking at here

By the way, the Ball Hamilton escape pinion overall length is 4.88mm (less the broken pivot).

-David