Here is a picture I took of a new clippers that Liam at the Waldorf barbershop recently acquired. It's a Made in Germany clippers. I was debating with Liam about the age of this machine. Judging by the warranty and the instructions leaflet, and the illustration on the box, I'd guess late 40s to mid-50s. Liam thinks it's more modern, maybe 60s. In any case it does work and do a really good job. It's got a slower motor just like the Oster. There is a blade that is a 00005 which did give a tighter result than the Oster. There is a large chrome beak that juts out so it takes longer for the metal blade to heat up. That's one thing that I love about the Oster.
Below is a great clip about a barbershop in the late 50s. You can see that the barber is using a barrel type clippers.