Expert: Martin Meyer - 4/24/2008

Question
Hello, I have not read anything to date which explains an odd problem with a Kundo anniversary clock which I have recently purchased. When turning the minute hand clockwise to set the time the hand will speed up on it's own for some variable duration. The speed is faster than a second hand would be and the duration can be anywhere from 10 minutes distance to 45 minutes distance on the clock face. I would like to understand this, can you explain or point me to some viable reference? I skill level is low however I do understand the basics of being in beat, delicate suspension spring and some basics of the drive train. I suspect the answer lies in the part of the train which I understand the least which is where the rotary motion from the torsion suspension spring interacts to the drive train.

Answer
Hi Dee,

The condition that you describe is called "fluttering", and relates to the anchor, or "verge", releasing several teeth of the escape wheel at a time, instead of releasing one tooth at a time as it should.

The anchor is the V-shaped part which moves back and forth at the very top of the gear train, and has two tooth-like parts at its tips, the "pallets". The movement of the anchor is initiated by the rotating pendulum balls; there is a long post at the top of the anchor which is moved back and forth by the fork near the top of the suspension spring. As the anchor moves back and forth, it alternately releases one tooth of the escape wheel at a time from the left and right pallets. In actuality, the power of the mainspring is delivered to the escape wheel, and the escape wheel gives the pallets a push each time a tooth is released, thus keeping the anchor moving back and forth, and keeping the pendulum swinging.

In 400-Day clocks, the depth that the pallets engage the escape wheel teeth at each "push" is very critical. When you move the minute hand forward, you are giving the gear train a large amount of extra power. If you happen to be doing this at the moment that the anchor is in a central position, that is, between contact of either pallet with an escape wheel tooth, it is normal for the anchor to flutter.

However, if the minute hand continues to move (flutter) on its own, the escapement may be out of adjustment. This can be due to the pallets having insufficient depth of engagement with the escape wheel teeth, i.e., being too high, or it can be due to the position of the fork on the suspension wire being a bit too low, and thus not causing the anchor to move far enough in both directions.

If the clock runs properly, this is not a condition that I would worry about. The escapement on 400-Day clocks is exceedingly difficult to adjust, and should only be worked on by a qualified 400-Day clock repairer.