Expert: Martin Meyer - 3/15/2008

Question
QUESTION: CLOCK LOSES 2 MINUTES AN HOUR. I HAVE BROUGHT IT TO 2 DIFFERENT CLOCK REPAIRMEN WHO HAVE NOT RESOLVED THE PROBLEM, BUT HAVE CHARGED ME IN EXCESS OF $175. IT HAS BEEN CLEANED BY BOTH REPAIRMEN, RUNS WELL, WITH THE EXCEPTION OF
LOSING 48 MINUTES PER DAY.  THE MOVEMENT ADJUSTMENT ON THE PENDULUM WILL GO NO HIGHER. CAN YOU HELP ME?

ANSWER: Hi Anthony,
    A loss of 48 minutes per day is greater than the limit of regulation, and indicates a problem other than an adjustment of the regulating nut on the pendulum.
    "299M" is not a Hermle number (it may be a clock manufacturer's number), so I don't know what type of movement you have. If it is a mainspring (as opposed to a weight driven) movement, make sure that you are winding the clock all the way, as far as it will go, every week. This is critical!
    If the work you had done included a complete overhaul, with complete disassembly of the movement and rebushing of worn bearings, the  problem almost has to be in the pendulum assembly. The pendulum, suspension spring or pendulum leader may be too long.
    If the work you had done was only partial repairs and did not include rebushing of worn bearings, this is most likely the source of the problem.

---------- FOLLOW-UP ----------

QUESTION: Thank you for your response. This is a Hermle triple chime, chain driven movement additional movement number 1171-850/114 cm.  The most recent repairmean told me that the bearings were in excellent condition and the clock did not require any rebushing of bearings. The pendulum is the proper length for the movement.

Answer
Hi Anthony,
    Your additional information rules out winding and bearing wear, so it is necessary to look for less obvious problems.
    First, observe the movement from the back. Near its top, you will see the verge (anchor) going back and forth, releasing one tooth at a time from the escape wheel (a wheel with saw-tooth shaped teeth, visible through a small opening at the top center of the movement plate). Watch the escape wheel; it should be releasing one tooth per pendulum swing in each direction, all the time and all the way around the wheel. If it is catching on the verge and not releasing a tooth at any time, this is the source of your problem. This is corrected by adjusting the depth that the verge engages the escape wheel teeth, and is definitely a job for a professional clock repairer. If your clock has a second hand, you can observe the same thing there; the second hand should advance one tick at every swing, and if you see it move slightly back and forth, but not advance one second, at any point, this is the same problem.
    Next, your clock has a "seconds pendulum" movement. This means that the pendulum should swing once per second (counting a swing to the left and a swing to the right as two swings). Use a stopwatch or accurate quartz watch to time the pendulum. It should swing 60 times in one minute. If it swings much less than that, the problem is in the pendulum and, if the above escape wheel check showed no errors, the pendulum or pendulum leader must be lengthened.
    Finally, if both the above tests show no problems, then the clock and pendulum are keeping correct time, and the error is in the "motion train", the series of gears that transfer the motion of the pendulum and gear train to the hands. This mechanism has a clutch, which is what allows you to turn the hands when setting the clock. If the clutch is loose and slipping, the actual clock/pendulum mechanism is keeping correct time, but the hands are slipping, and so not moving in synch with the clock mechanism and pendulum. You can sometimes observe this problem by looking very closely at the minute hand when it is in a rising position (between :35 and :50). You should be able to see the minute hand advance a tiny amount, a tick at a time, with every pendulum swing. If it does this when it is in a falling position (between :10 and :25), but stalls when it is in the rising position, then you have a loose clutch. Repairing the clutch is another job that is definitely for a professional clock repairer.