This video shows how that revolution counter of the Pin Wheel works and especially the tens carry mechanism. These counter display is also located on the carriage. (Don't bother the background noise, the neighbour is rebuilding his house.)
The counter has the value nine at the start. First that digit is set to zero. At that time a guided plate is sticked out. An pin from the wheel responsible for the tens carry is now guided to the adjacent digit and that digit is increased to one. To prevent having that happened at eleven the guide plate is pushed in by the bigger pin.
A more detailed look to the video shows more pins. For instance the one who passed first the still in place guided plate of the next digit. This pin is used when the wheel is turned counterclockwise for subtracting. Then the situations from ten to nine should be solved. But that's discussed on page 3.

The pretty clever and simple thing is to move the carriage in steps so that multiplications of the tens and hundreds etc. can easily carried out. This counter show the multiplicand.

On this page you will be able to see the various sequences of the Pin Wheel technology in moving pictures. I use the Thriumphator C1, which you see to the left, for that purpose. On the left the first one, the general overview of the machine at work, showing adding the numbers 9876543210.
First you will noticed after the crank is pulled out, the releases of the input number display from the slider gears.
Than it's fabulous to see how the various ridges move smoothly in between the counter gears. For instance the sliders pass the gears. Of course they should not touch anything. Then a pin for the subtract tens cary is passing, not active during adding. Then the stuck-out pins. They are inline with the number gears so the turn these gears. Direct after followed by the tens carry pins, but due to zero start, no ten cary have to be executed.
The second video is taken slightly from the left, in order to have a better view on the slider gear release. Prior to turn the wheel, the gears above are all pushed aside and the Pin Wheel can turn without changing the slider / input display.
After the turn(s) of the Pin Wheel the gear is put back in position to follow the setting of the sliders as seen in this video. You will see which gear of the Pin Wheel is connected to the smaller number gear above. And this will only used for that purpose and is not come into action for the calculation. The slider setting makes that visual.
Now a video of a successive adding. Here we add two times the same number 9876543210 to the result display. We do that by turning the wheel two times. The pins of the Pin Wheel are in line with the gears of the number wheels of the result display. The interesting new thing here is seen at the end of the video, the way the tens cary is executed. At the transition from 9 to zero there is a guided plate pushed out by a knock on the number gear. This is possible due to extra space is fraised in the Pin Wheel. The tens carry pin of the Pin Wheel will now guided to the next digit and the tens carry is a fact. You see that those pins are movable to the side. The fraised space ends and pushed the guided plate back on the original position.
We called this operation a successive adding which is in fact a multiplication. In this case times two. The turns of the pin Wheel are registered in the other number display of the carriage. The next video shows more details.

An very illustrative animation of a Pin Wheel machine via You Tube.

Pin Wheel Technology (page 2)