Citizen launched their first automatic watch in 1958 – it was something of a stop-gap model prior to the appearance in late 1961 of the Jet range. The ‘Auto’ was made with either 20 or 21 jewels, and the movement was designated the ‘3KA’. Running at 18,000 beats per hour, the movement used a centrally pivoted rotor, swinging in both directions and driving pawls to wind the main spring. My example is a 20 jewel version:
The font used is unique to the Auto, whilst the back is quite deep to house the winding mechanism:
The movement is hidden under a full bridge which holds the auto winder:
One of the pawls can be seen through the left ‘window’in the above image.
This is a rare watch, one of only a very few I have seen. It has been the subject of a full service and restoration by Brian aka ’31 Jewels’. And as I pieced together research material on this model, I uncovered an interesting back story to the movement. This, and the restoration, is fully documented on the Citizen Auto page: https://sweep-hand.org/the-citizen-auto-1958/