Here is the program wheel completely disassembled with all of it’s satellite wheels removed for your scrutiny.
Wheel number one advances the decade wheel of the date onenumber for each of it’s four teeth. The reason for the uneven spacingis 10 days from 1st to 10th, 11th to 20th, and 21st to 30th. But only 2days from 30th to 31st and then back to the 1st again. So as one can see, the program wheel makes one complete revolution per month.
Wheel number two is the February 28th wheel. Lookingcarefully at it one will see that it only has three large teeth. Thatallows for leap year programming so that in leap years it will showFebruary 29th. The wheels on its left, together with the single tooth seen under wheel three, are its driving wheels.
Wheel number three has five long teeth for the five months whichhave less than 31 days. February, April, June, September and November.
Wheel number four has one long tooth for February 29th. Wheels number three and four make one revolution per year.
Wheel number five is the date wheel. Its 31 teeth accomplish the changing of the date.
The 31 tooth brass wheel under wheel number two is the actual driving wheel that drives the complete program wheel assembly.

Now we get to put it all together as a complete unit.

This close-up shows the longer teeth in position to effect the jump from February 28th and February 30th, or any month that doesn’t have 31 days. What about the tooth for February 29th? That wheel fits on top and is in the next photo.

Here one can see all the wheels in position ready to effect the jump from February 28th to March 1st.

The 24 hour wheel has four long teeth which engage the programwheel in order to flip the date either one, two, three or four days,depending on the month. Tooth #1 engages the green arrowed tooth. Tooth#2 engages the blue arrowed tooth. Tooth #3 engages the red arrowedtooth, and tooth number four always engages the brass driving wheelonce a day to effect the date change, including from the 31st to the 1st.

The overall view before the last of the program wheel, the date wheel, is fitted.

Before the top plate for that section is fitted.

Voila!! All completely assembled ready for the fitting of the indicator discs.

A close-up of the holes to help the watchmaker with programmingit correctly. This shows the month wheel set for March. The otherwheels have the holes set for February 28th so that the watchmaker can set them correctly, and then check that it does indeed jump from the 28th to the 1st.

All the wheels in place and ready for the dial and hands to befitted. Note that the programming is not correct as this photo wastaken while I was disassembling the watch, prior to servicing.