Suspension Springs in American Clocks

[Arthur Cagle]

How critical is the length of a suspension spring in an American movement, as long as the overall length of the pendulum leader is correct?

 

[Willie X]

Not that critical.

The active length can be as short as about 3/8" but a 1/2" minimum would be a pretty good rule of thumb.

Willie X

 

[Arthur Cagle]

Not that critical.

The active length can be as short as about 3/8" but a 1/2" minimum would be a pretty good rule of thumb.

Willie X

Thanks, Willie. Would a longer spring adversely affect running ability? I had to replace the leader on the Atkins I'm working on, and the stock one I put on is about an inch long. The broken one was about 1/2 inch, and half the width had been cut out. It wasn't running when I got it, and it still isn't. I rebushed, have checked the endshake on the train, the pivot holes seem to allow the required lateral movement, and the mainspring is fine. The wheels all move well with power off. I've checked all teeth, every trundle, every solid pinion both teeth and hubs. I'm running the time train without the strike train now. I'm still having an obvious power loss. Any suggestions beside an exorcism?

 

[R. Croswell]

Thanks, Willie. Would a longer spring adversely affect running ability? I had to replace the leader on the Atkins I'm working on, and the stock one I put on is about an inch long. The broken one was about 1/2 inch, and half the width had been cut out. It wasn't running when I got it, and it still isn't. I rebushed, have checked the endshake on the train, the pivot holes seem to allow the required lateral movement, and the mainspring is fine. The wheels all move well with power off. I've checked all teeth, every trundle, every solid pinion both teeth and hubs. I'm running the time train without the strike train now. I'm still having an obvious power loss. Any suggestions beside an exorcism?

Before arranging an exorcism, I would round up some of the usual suspects for questioning:

1) Does the escapement operate when you move the pendulum back and forth by hand?
2) Does the suspension rod have a small clearance in the crutch loop?
3) Is the suspension rod touching either end of the crutch loop? (it must not)
4) With the movement on its back with power let down, when lifted with a probe does each wheel drop under its own weight? (it must )
5) Repeat #4 face down.
6) is the movement "in beat"?
7) With the verge removed and the mainspring let down, do the wheels begin to turn almost immediately when winding begins (2 or 3 clicks is good)
8 With the main spring let down, turn the main wheel back and forth, do any pivots "dance around" in the pivot holes?

A good video, at least 30 seconds, up close to the escapement and in focus might be helpful.

RC

 

[shutterbug]

A longer spring might lengthen the pendulum oscillation. Might be beneficial in some circumstances.

 

[Arthur Cagle]

OK, now I feel like an idiot. I tore the movement down again, started with the basics. Lo and behold, when I first checked the bushings I installed I somehow missed that the second wheel rear bushing was too large...the wheel would lay way over. I swear I checked those, but I missed it, mea culpa!

So, I rebushed that location and it's been running strong for three hours now. I hope that was the only problem. We shall see!