New to me;
"The Tungsten Distributor" Glendale Engr Co
Glendale California Patent 1340867
Four rollers open with a single flat side cam
Red line shows tungsten points
Seems like top quality workmanship
I had a Duntley timer that was similar.
Here's the Accessory Of The Day post for the Tungsten timer.
They are good timers, I've used three or four over the years. They do not last forever, however, the points get worn and pitted and performance suffers. The flat sided rotor does wear at the leading edge some. Interestingly, the fiber rollers seems to last. All in all a good timer, though.
I think the Duntley-Tungsten-Fansteel concept is a good one. It is what I call a "triggered" timer, as opposed to a "wiper" timer (Newday - Anderson e.g.) In a triggered timer the ground is provided directly from the timer case. In a wiper timer, a cam mounted "wiper" grounds through the camshaft.
Here is a 'scope trace of each. You will notice how "itchy and scratchy" looking the wiper timer is and how nice and flat the triggered timer is.
Great info Tom.