Okuma ever used DC spindle drives on LB lathes??
Afaik, DC spindle drives were mostly a Gildemeister thing, early NEF CT40 and similar had them.
aus dem Rückbau einer NEF / Gildemeister CT-40: Einbau Stromrichtergerät Hersteller: Baumüller...,Baumüller Stromrichter MPG – 2.85005 (NEF / Gildemeister CT-40) in Nordrhein-Westfalen - Warstein
Also common on early Maho-C and Hermle milling machines, better Okuma/Fanuc machines switched to AC spindle drives quite early on.
My Okuma ACT4 from 1982 already used AC spindle and DC servo, Puma8/Fanuc10T from around 1988/1989 is aready full AC-Spindle/Servo.
DC-Servo are OK, AC servos usually run smother, DC-spindle is a thing that I usually avoid, due to brush/commutator wear, already fried a couple of DC-motors on my washing machine, don't need that on my machinery if there are other options/a second hand market filled with old iron ;-)