Making up lost time
The clock is back together and I’m starting to tune it. I’m laboring at the “keeping it running” stage. It is running a bit sluggish and frequently the escapement arbor does not advance quick enough causing it to skip a beat (sometimes even two).
I suspected friction so I went through it three or four times - cleaning and adjusting the exact seating of the arbors, stands, etc.
When I picked up the clock in Chicago, Mark had a different weight (approximately 80 pounds) and suggested it needed 15-20 additional pounds. I installed the original weight which is 218 pounds on a pulley and provides about 109 pounds of uncompounded force.
I could add another 20-25 lbs but that just doesn’t seem right.
Clearly the escapement is either under-powered or you have some binding somewhere in the train. This is a very high-ratio train - it has five wheels, so it very susceptible to any points where friction might come into play. The way I attack this is to tear it down, starting from the lowest point in the train (the winding barrel) put it together and check for free spin. Go on to the next wheel down the train and so on. With no weight on it check for proper ‘end shake’. Each arbor must freely slide horizontally between the bushings at all rotational angles. The old saying, ‘if it don’t rattle it won’t run’ is true. Another trick is to run the clock just as in the video, start loosening bushing bolts by 1/2 to 1 turn from the upper train down, and see if a surge of strength occurs. If so you have either a miss-aligned, damaged bush, or a poorly finished, bent pivot, (or more rarely, a bush out of rotation but this is hardly ever possible as they are not easily interchangeable).
I went through the entire trail again. I was pretty sure the resistance was in the last gear to the escapement but given all the gears in the train, I followed Mark’s advice and went back to the beginning.
I believe I have found the problem. I kept looking at the gears for the resistance but it turns out most of the resistance is in one of the escapement “arms”. There photo depicts the two long arms which hang from their attached long thin arbors.
The escapement arbor turns more slowly when the pendulum swings to the right. During this phase, the escapement arbor is trying to “cock” the left arm. This arm is providing too much resistance.
Part of the problem is resistance in the arm. I’ve eliminated some of that. The other problem is the clock is not perfectly balanced and level. I thought the adjustable ends on the two arms (seen at the bottom of the photo) would solve that but I forgot that the slight off balance nature of my installation means the two arms will want to lean a bit to the right. This means the right arm applies a bit less resistance than normal and the left arm applies a bit more resistance than normal. This is exactly what I hear, when listening to the clock - a solid clank in one direction and a less solid clank in the other.
Balancing the fully installed clock will be a bit tricky but I think that should resolve the issue. (Fortunately, a small 4 ton hydraulic jack makes pitching my clock tower is a lot easier than righting the tower of Pisa <grin>)
Addendum: Turns out the clock was pretty close to perfect level and true. I disassembled the entire clock and the escapement and adjusted every bushing, every arbor, every bolt, and every screw. I found some additional resistance in the left arm of the escapement but not enough. So, in the end, I added 20 pounds … oh well !
As the addendum states, I gave up and just added more weight
Dear Glen,
Such a painstaking process. Amazing really.
So - it wouldn’t be a real comment post on my part without a question! Here goes:
I understand from your post above that friction, mis-alignment, any sort of resistance really, can make the clock mechanism run irregularly. (k - here REALLY comes the question now
) Many of these clocks were installed in clock towers. Birds and all manner of wildlife could get into these places and - well - excrete in an indiscriminate manner, sometimes on the works. Not to mention - clock towers, especially old ones, we transparent to external temperature variations, dampness etc.. Did all those environmental issues affect the running of those old clocks or did they use such an enormously heavy drive train that environmental issues were minimized? OR do you think these babies were covered some how to keep out most of the grossest of environmental insults?
Best,
Roy
Hi Roy,
Like most machines, tower clocks work best when they are assembled and “run in”. Over time, the friction points wear and, like a new engine, once it is broken in a bit, it can be pushed hard and still hold up. As Mark put it, ” if it doesn’t rattle, it won’t run”. These clocks have a lot of play and slop in the mechanisms.
Further, on a weekly basis, most old tower clocks had someone check in on in, oil things etc. My old clock was nearly black with oil and dirt *but* the arbors, gear teeth, and the escapement arms were pretty clean.
The problems I am dealing with are three fold. First, one of the gears took a serious beating at some point in its life. The fourth gear in the train must have broken at some point along with it’s no longer round or true. Second, I replaced the horizontal support of the escapement arbor with a vertical stand. I did this to bring the clock back to what I think was the original design. Back to my first point, a new part needs to wear in. Third, the moment the clock was disassembled, restored, and reassembled. The “wear in” period had to start all over again.
I found a way to accelerate time (so to speak) running the gear train of the clock at nearly 30 times normal speed. I ran it this way for about 8 hours - or the equivalent of 10 days of continuous running. This has helped considerable. I could not run the arms of the escapement at this speed so those are having to run at normal speed. the added weight is helping it through the break-in period. After a week, I expect to remove 10 lbs of the extra weight and at the end of a month, I expect the clock to be running smoothly and the last extra 10 lbs will come off.
BTW - some clocks were “boxed in” but most were left dirty with the exception of the bushings and gears. These got copious oil treatments (and I mean copious). The oil took care of both lubrication and rust prevention.
As for the “pain” in painstaking - it’s all good. There is something very rewarding working on physical things like old mechanical machines … much more rewarding that computers and software. It’s a blast when you breath life back into an old machine.
Thanks Glen.