Regulating 400 Day Anniversary Clocks

400 day clocks with a three or four-ball pendulum have a regulating disc near the top of the pendulum. On Kundo and Schatz clocks, turning the regulating disc clockwise slows down the clock; and turning it counterclockwise speeds up the clock. Some brands of 400 day clock regulate in the opposite direction. The clock usually has labels to tell you which way to turn the disc.

The photos below show typical regulating discs.

An effective way to regulate a 400 day clock is to grasp the pendulum when as comes to a stop at the end of a rotation, hold it in place, turn the regulating disc, then release the pendulum. This a good procedure as long as you are CAREFUL NOT TO YANK DOWN ON THE PENDULUM, AS THE SUSPENSION SPRING IS THIN AND COULD BREAK.

  1. When the pendulum comes to a stop at the end of a rotation, grasp the pendulum in one hand and hold it stationary. Lift it up slightly to take the pressure off the suspension spring;
  2. With your other hand turn the regulating disc a small amount (Clockwise for slower, Counterclockwise for faster);
  3. Release the pendulum, and the clock will start going again.

This procedure is good because it doesn’t disturb the rotation of the pendulum very much, reducing the timekeeping variations caused by the changing the amount of swing of the pendulum. And it doesn’t disturb the pendulum as much as taking it off would.

Video showing the procedure:

For clocks that have a pendulum lock, (such as the Schatz “London Coach” many Kundo clocks), you can lock the pendulum and then turn the regulating disc.

  1. When the pendulum comes to a stop at the end of a rotation, use the locking lever to lock the pendulum in place;
  2. Turn the regulating disc a small amount (Clockwise for slower, Counterclockwise for faster);
  3. Gently unlock the pendulum. The clock should start.
  4. (If the clock doesn’t start, gently rotate the pendulum 1/2 turn and release it.



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  1. The fork on the suspension spring may need to be moved up. Or the movement may need to be overhauled.

  2. Hi Bill, thanks for all the great information.
    My question is; What makes the pendulum rotate more or less? My 400 day schatz keeps going however the pendulum is only rotating a 1/4 turn in each direction. That may be too little to keep acurate time. I remember my grand perents clock moving alot more than that.
    So what do i need to adjust, to get more rotation from the pendulum?

  3. Should I replace the suspension wire with a new one we know that is correct? If so where can I purchase the correct one?

  4. The clock runs smooth but fast. Where can I purchase the correct spring? Is it possible this one may have worn out or been stretched or something?

  5. The suspension spring may be too thick. Or, is the clock “fluttering” (ticking really quickly sometimes)?

  6. My Kern 400 day anniversary clock will does not have any more adjustment left and it still runs quite fast. The balls do move out further when adjusted but are all the way out now. I see some people mention it may have the wrong spring?? Please advise.

  7. Our clock is running too slow and we have turned the disk as far as possible to fast. Wire had broken but replaced with new ( 10, wire was no 9) wire. Thsnks

  8. Hi, I have a Kern miniature 400 day anniversary clock, I have got it “in beat” and have been trying to regulate it as it is running slow, I have now run out of adjustment on the regulator disc which is now turned fully in the clock wise direction.

    Could it be the suspension spring is too Long/Short or Thick/Thin .

    Many thanks

  9. If the disc is all the way clockwise, it may be that the suspension spring is slightly too thick. It could also be that the escapement is “fluttering” (moving rapidly at times) in which case the fork needs to be raised slightly, which a repair shop should probably do).

  10. I have a Schatz standard anniversary clock that is running fast. I have been turning the wheel clockwise over several days to slow it down. It has slowed down but is still running fast. The wheel is now very tight and I’m worried if I turn it any further I may damage the clock. Is there another adjustment I can make to slow it down?

  11. Turning the disc clockwise should be slowing the clock down. Are the balls moving outward as you turn the disc? The balls being further from the center is what makes it slow down. Are you setting the clock to the current time after making each adjustment?

  12. This works with my Kundo-up to a point. I’ve continued to regulate slower for several days but now, each time I move the disc clockwise, the clock speeds up! Is there a point where the regulator goes into reverse?

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