pendulum swings for 1minute, then stops

Posted: Tue Jan 26, 2010 5:08 pm     Post subject: pendulum swings for 1minute, then stops

I have an emperor clock built from a kit in 1975. I have oiled it when it slows or stops over the years. Recently I removed the movement and face for oiling the front shaft pivots. Now that it is reassembled, the pendulum won't continue past one minute. The movement is as level now as over the past many years, since it is in the same location. I notice that when I start the pendulum, the suspension springs have some twisting during movement, rather than perfect lateral movement, as if rotating torque is being applied. I try to move it perfectly lateral, but I can always see some torque. Since it stops in one minute, I can't watch long enough to see if the slight twisting would be corrected by gravity. As the pendulum slows, it shudders or vibrates as it comes to a stop. Please help.

Posted: Tue Jan 26, 2010 5:41 pm     Post subject:

Sounds like in the oiling process you changed the verge position. Here is a posting from Chris @ Klockit

The pendulum might require a beat adjustment. If you know that the movement and clock case (the movement most importantly) are level, then the next step is to make certain the pendulum is in beat. The pendulum typically attaches to a metal piece called the pendulum leader. The pendulum leader, in turn, is typically fed through the crutch arm, which is an arm that extends out the back plate of the movement. Remove the pendulum and slide the pendulum leader out of the crutch arm slot. This crutch arm must swing an equal distance from center to left as it does from center to right. If it is uneven, then you can push through slight resistance so that you can gain an even swing. Replace the pendulum leader and pendulum. This would be typical for many brands of mechanical movements

Posted: Tue Jan 26, 2010 11:02 pm     Post subject:

Thanks for the reply. Is the slight twisting of the suspension springs normal or indicative of the need for the adjustment you suggest?
I have read this posting regarding beat adjustment. If I understand correctly, the pendulum leader not only engages the crutch arm, but then hangs on 2 pins that come out of the suspension spring. This is what mine does. Am I supposed to be forcing a symmetrical lateral movement of this arm? If so, I would have to say that no such abnormal force was applied during oiling, so I don't understand how it occurred.

Posted: Wed Jan 27, 2010 3:37 am     Post subject:

actually if you follow the leader to the top of the movement you will see the verge (looks like an inverted V which rocks back and forth) which engages the escapement gear. There is a clutch mechanism which regulates where the verge hits the gear, does not take much force to move it. Here are a couple other links.


http://billsclockworks.com/merchandise/instruction-sheet.html/19
http://www.clockworks.com/cintro3.html

Posted: Thu Jan 28, 2010 8:19 pm     Post subject:

I remain concerned about the twisting associated with the lateral movement of the suspension springs. Is this normal?
I have not recognized the swing to be out of beat. Tick tock is uniform until it slows at 30 seconds. Also, the bob is eqidistant from the sides of the case during the swing until it begins to slow. This suggests a symmetrical movement of the verge, or does it?

Posted: Thu Jan 28, 2010 10:38 pm     Post subject:

Not necessarily. If the tick tock seems uniform, that would be a better indicator than measuring the distance between each side of the pendulum and case assembly. That being said, hearing an even tick tock may not necessarily mean that the clock is in beat. You can see if the pendulum will swing longer once you perform beat adjustment. If it does swing longer, then you know it is an issue where beat adjustment will correct the problem.

I am not certain what you mean by the suspension spring twist. Pendulums may tend to twist when you initially start them, but they normally level (symmetrically) out if they are able to maintain the swing. The important thing with the suspension spring is to make certain the thin bands between the suspension spring plates are not broken (which would give you a lot of twist in your pendulum action). Since your pendulum is unable to keep swinging, and if the bands of the suspension spring are intact, it would seem that the problem is more indicative of the movement requiring adjustment to the beat than any sort of problem with the suspension spring itself.