Fourth wheel to center wheel: 5:1 (on which the minute hand is mounted).

The table below gives the ratios: Accutron 230 Wheel Train (numbers of teeth) 230 The challenge of achieving the reduction ratios required in such a confined space was met by having very small pinions of mainly 6 teeth, and large wheels with a high tooth count, and arranging them in vertical 'layers'. But efficiently is exactly what Bulove did when they designed this movement. The battery uses 35% of the area of the movement, but the remaining 65% is a very awkward shape and hard to use efficiently. The 230 series movement draws the same current as a 218, so it needs the same size cell to give a year or more run time. This movement uses a 344 cell, same size as in a 218 movement. There is very little room in this movement for the wheel train. Then, on looking at the overall size and layout of this movement, it soon becomes clear that there may be a good reason for this. At first glance they appear almost triangular in shape, rather than the epicycloid-hypocycloid shape normally seen in watches. One of the unusual features of the 230 series movements is the shape of the train wheel teeth. The electronic circuitry had been miniaturised from previous tuning fork watches, and had one set of disk-shapedĬoil windings which extended between the magnetic ends of both of the tuning fork tines.

It could be obtained with or without a sweep second hand.

The larger size (23.5mm) was used in men's watches also. It was available in two basic sizes, the only difference being the bottom or pillar plate. The Model 230 Accutron was the first tuning fork movement small enough to be offered as a Ladies watch.

Accutron 218 tuning fork frequency