Thumbwheel to Stem Attachment

The way the thumbwheel on the top of the adjuster is attached to the stem also differed between prewar and post war. It was not uncommon for pre war thumbwheels to be attached by a broached hole. That is the hole in the thumbwheel is not round, but is more of a rectangle or oval ( see the steel portion in the middle of the wheel). The end of the stem is shaped into a similar shape, so when the thumbwheel is attached, there is a strong connection which resists twisting. The photo shows the broaching and the patent date.

Here is an earlier patent date, Patent No 11526 - 13 . Note that the thumbwheel is steel not brass and does not show signs of being broached.

Post War Norrises typically do not bear patent dates or signs of broaching.