long-case intermittent strike jamming

[kinsler33]

This clock occasionally stops just before the rack is to be dropped onto the snail. It seems that the gathering pallet is jamming onto the rack's stop pin, which prevents the rack from moving slightly as the rack hook rises.
The rack hook has to move a very small distance because both the rack hook and the rack teeth are slightly slanted and tend to lock together.

The totally-immobilized rack prevents the pin on the hour wheel from pulling up the rack hook to release the rack. This stops the hour wheel and thus the clock at about five minutes to the hour.

I'd removed, polished, and generally improved the rack hook and its pivot, which I originally thought were guilty, and polished every other surface I could think of prior to getting smarter and finally running the clock without its dial. There's no visible corrosion on the rack pin or the gathering pallet, but I'll try polishing and perhaps lubricating this steel-to-steel contact point.

But I'm not at all confident in my diagnosis, for this is perhaps the fourth attempt at curing the problem. Has anyone else run into this sort of symptom?

Mark Kinsler

 

[Thomas Sanguigni]

How about the rack pivot itself? Where it is pinned to the plate it could have rough spots. I just repaired an ISGUS from hell, and it had this problem. The rack just would not fall. I broached the connection lightly, and smooth broached it too. The mount post had a little 3/0 emery paper, as well. It now drops very well.

 

[kinsler33]

How about the rack pivot itself? Where it is pinned to the plate it could have rough spots. I just repaired an ISGUS from hell, and it had this problem. The rack just would not fall. I broached the connection lightly, and smooth broached it too. The mount post had a little 3/0 emery paper, as well. It now drops very well.

Thank you. I'll look at that as well.

The rack, however, has a very smooth action and is also spring-driven. Had the rack hook lifted up without dropping the rack, the clock would have kept running. In this case, the rack hook is somehow blocked from lifting, which also blocks the pin on the hour wheel that contacts it once (no half hour on this clock) per hour. And that effectively stops the time train dead.

I'm thinking of putting a dab of molybdenum disulfide chassis lube on the tail of the gathering pallet. It's an extreme-pressure grease that forms a weird--but beneficial--layer of oxide on the steel parts that it contacts. This oxide prevents the formation of micro-welds that can form between parts when the normal boundary-layer of grease is breached.

Mark Kinsler

 

[Thomas Sanguigni]

One other thought, could there be binding by the plates? Once pinned back together, there may be a bind causing the gathering pallet to slow or stop. During reassembly, I'm guilty of not pinning the plates, and I just hold them. I've been stung a few times doing this.

 

[Bruce Alexander]

Mark,

Are there signs of wear to the Rack Hook?
It should be able to lift away from that last Rack Tooth without having to force the Rack against the Gathering Pallet. If you lift it manually, do you feel resistance?
It looks like it should form a neutral arc relative to the Pivot...kind of like the locking surface of a deadbeat escapement vs. the action of a recoil.
If a slight notch has been worn into the Rack Hook, that may be resulting in the lock up.
I've never worked on a mechanism like this so exhaust all other possibilities. If nothing else works reliably, you might try carefully dressing out any worn "notching" of the Rack Hook until it can lift without exerting force on the Rack. Make multiple small adjustments and test by manually lifting the Rack Hook.

Good luck with it,

Bruce

 

[kinsler33]

Thank you. I have buffed and polished that rack hook and everything it contacts until it's ready to be displayed in the main show window at Tiffany's.

Just for the heck of it, however, I went outside with one of my little Chinese plastic parts jars, found my grease gun, and filled the jar with a hideous black worm's worth of chassis grease. This is an extreme-pressure lube that I use on the universal joints of my '64 Econoline van, and it seemed to me that it might be worth experimenting with. So with the tip of a small screwdriver I applied the tiniest of smears of this evil-smelling stuff (molybdenum disulfide smells like it sounds) to the tip of the gathering pallet and the stop pin on the rack. I think it's these two parts that are jamming together.

And the clock refuses to stop: it's just ticking along with its invisible smear of grease. I will report on future progress, for this is hardly an ideal solution--yet it may be the only effective one given that it's a steel-to-steel contact friction problem.

Mark Kinsler

 

[Bruce Alexander]

Mark,

Sooner or later that grease will wear off.
It wasn't so much a matter of a friction as shape.
We can't really see the shape of the Rack Hook since it is hidden behind the Gathering Pallet.
If the parts that slide against one another are shaped so that they don't lock, then I'm at a loss to explain why things are locking up when the clock tries to unlock and go into Warning.

You said:

The rack hook has to move a very small distance because both the rack hook and the rack teeth are slightly slanted and tend to lock together.

If that "slant" is due to wear, you may wish to consider "dressing" the Rack Hook to remove the slant and return the part to its original shape.

Good luck with it.

Regards,

Bruce

 

[kinsler33]

The grease is an experiment, but it has worked quite well. Insofar as I can tell the tail of the gathering pallet was somehow jamming into the stop pin on the rack. What I may do is give that pin a bit of a bend to keep the rack and gathering pallet from hooking together, however they were doing that. I'll take some pictures and investigate more thoroughly before I put the dial back on tonight.

Mark Kinsler

 

[Bruce Alexander]

How is the gravity assist spring on the rack set up?

 

[kinsler33]

Funny-looking flat spring screwed to the front plate. The rack's arm is long and stands almost vertically on its pivot, so the spring is needed to pivot the rack tail up underneath the snail. It's not a really strong spring.

Mark Kinsler

 

[Bruce Alexander]

Hi Mark,
I guess that I'm wondering if it is set up on the right side of the Rack Tail. Usually gravity assist springs like that are used to make sure that the Rack drops completely against the Snail. They are not used to help gather the Rack. I've never come across a movement like this one. It may have come into your shop set up that way but have you tried to operate the mechanism with the assist spring set up on the other side?
Regards,
Bruce

 

[tom427cid]

Hi all,
Couple of things to consider. First,how much run up on the warning pin? I have found that if there is not enough-about half a revolution- it will not allow the time for all the parts to position themselves. The rack spring only wants enough pressure to move the rack for the 12 o'clock strike. Secondly, the rack stop pin might want to be a bit closer to the GP. in other words stop the GP a bit sooner. One other item to check is how far is the rack hook raised. If it is to far this will cause issues.
These would be IMHO the items I would check for intermittent stopping.
Hope this might help.
tom

 

[wow]

Just a thought....Bruce got me looking at the rack spring and I think one of the main purposes of it is to keep the rack from bouncing once it hits the 12 o’clock drop. It should be set just tight enough to drop the rack to 12 o’clock, like Tom said, but it should hold it there and not let it bounce and jam.

 

[kinsler33]

Hi Mark,
I guess that I'm wondering if it is set up on the right side of the Rack Tail. Usually gravity assist springs like that are used to make sure that the Rack drops completely against the Snail. They are not used to help gather the Rack. I've never come across a movement like this one. It may have come into your shop set up that way but have you tried to operate the mechanism with the assist spring set up on the other side?
Regards,
Bruce

The photograph may be slightly deceiving, for part of the rack assist spring is hidden beneath the rack arm's extension. The spring has an extension on it that tends to push that extension toward the right which, due to the pivot above, tends to tilt the whole rack toward the left.

Mark Kinsler

 

[Bruce Alexander]

The photograph may be slightly deceiving, for part of the rack assist spring is hidden beneath the rack arm's extension. The spring has an extension on it that tends to push that extension toward the right which, due to the pivot above, tends to tilt the whole rack toward the left.

Mark Kinsler

Mark,

Okay. Thanks for clearing that up. I go back to my original suggestion/question that if lift of the Rack Hook, as it lifts out of lock, forces the Rack to the right against the Lock Pin, the contour of the Rack Hook/Rack needs to be adjusted so that the lift doesn't cause the Rack to be forced into a tighter lock. Is it possible to show the part of the Rack Hook which is hidden behind the Gathering Pallet? How does it look to you? If you carefully lift it manually, is there any resistance? Does it hang up slightly?

Regards,

Bruce


Edit: Something else Mark, as Tom & Will pointed out, you don't want too much tension on the gravity assist spring. If it is exerting a lot of force beyond what is necessary to ensure that the Rack falls to the 12:00 step on the Snail, it may need adjusting. If it is forcing the Rack to the left when it is lock, it may make the lift into Warning more difficult.

 

[shimmystep]

Hi Mark, the issue you have is that the gathering pallet is pushing the rack backwards, and hence pushing the first rack tooth against the rack hook. The problem is the shape and length of the gathering pallet. The gathering pallet tail needs to be more on top off the stop pin, as opposed to pushing against the stop pin.

Often there is a small rut in the rack hook where the first rack tooth sits, which may not be helping.

The gathering pallet may not be the original and looks a little short for where the stop pin is.

A pic below that shows the difference, i.e the gathering pallet in the pic is more on top than against the pin

 

[kinsler33]

Thank you both. It does seem that the gathering pallet is wedging itself into the rack pin, and that it shouldn't be doing that. I think the easiest way to deal with this is to either bend the rack stop pin a bit or perhaps increase its diameter a bit. There's no way to determine if these parts are original, but I think I should be able to correct matters. Thanks very much.

Mark Kinsler

 

[Bruce Alexander]

Mark,

If the part is not new, I think you could reasonably assume that it was working at one time. If that is true, it begs the question "What has changed?". Once again I would assume that there has been some wear to the sliding parts, but if you don't see any evidence of it, you might consider rounding the bottom of the leading edge of the Gathering Pallet so that it can't jam. The pin on the Rack is pretty short and stout looking. I have to wonder how much bend you'll be able to achieve and even if you do, the root of the pin isn't going to move. Will the Rack even land on the bent part?

Please let us know how you resolve the issue.

Good luck with it.

Bruce

 

[gropa011]

Mark,

If the part is not new, I think you could reasonably assume that it was working at one time. If that is true, it begs the question "What has changed?". Once again I would assume that there has been some wear to the sliding parts, but if you don't see any evidence of it, you might consider rounding the bottom of the leading edge of the Gathering Pallet so that it can't jam. The pin on the Rack is pretty short and stout looking. I have to wonder how much bend you'll be able to achieve and even if you do, the root of the pin isn't going to move. Will the Rack even land on the bent part?

Please let us know how you resolve the issue.

Good luck with it.

Bruce

Hi,

 

[gropa011]

Hi,

Sorry, seem to be messing up this post. I have a similar problem. I haven't run an 8 day longcase for years because it stopped on the strike. Decided to fix it for Christmas. Last time I cleaned it I put a new gathering pallet in. It fits exactly as Mark's does and stops about 1 o'clock on the rack pin. The rack spring pushes the rack anti clockwise, away from the gathering pallet arm, and the rack falls onto the snail. So I don't see how it could jam... Now I am far from an expert! Light years. So maybe I have not clearly understood. This new pallet has worn a groove already, where it contacts the rack teeth. So I may look for another one, I would prefer a longer am as Shimmystep suggested.

 

[kinsler33]

Hmm. I returned that clock a few months ago and at the time I wasn't making notes on my repairs, which isn't so bright either. If I recall correctly everyone diagnosed the difficulty as one involving wear, which shouldn't have been a surprise. I _think_ I may have built up a worn section of either the rack or the rack hook by soldering a bit of hard-steel suspension-spring stock thereupon. Silver solder would have been better but I don't know how to do that yet, and I was pleased with the appearance of the repair.

There were other issues as well: the clock was apparently fashioned from a stock British movement and modified with an amazingly crude sheet-iron 'plate' added to the front. This provided a base for the moon dial and the calendar features, which apparently weren't designed into the original movement in, like, 1798. Lemme see if I can find a photograph of that...

...Rats. The only photographs I have were made before I finally admitted that I cannot hold a camera steady, so they're terribly blurred.

Mark Kinsler

 

[gropa011]

Sorry, seem to be messing up this post. I have a similar problem. I haven't run an 8 day longcase for years because it stopped on the strike. Decided to fix it for Christmas. Last time I cleaned it I put a new gathering pallet in. It fits exactly as Mark's does and stops about 1 o'clock on the rack pin. The rack spring pushes the rack anti clockwise, away from the gathering pallet arm, and the rack falls onto the snail. So I don't see how it could jam... Now I am far from an expert! Light years. So maybe I have not clearly understood. This new pallet has worn a groove already, where it contacts the rack teeth. So I may look for another one, I would prefer a longer am as Shimmystep suggested.

Just managed to get the photos to show. I see what Shimmystep means, the shape of Mark's gathering pallet is different to mine and it sits more like 2 or 3 o'Clock, so it could jam if the rack hook pushed the rack to the right(clockwise)! Thanks, this will help me look at my problem!

 

[gropa011]

English longcase ca. 1800, 8 day two train.
I have a couple of comments in the thread already. I have a similar intermittent strike problem but not caused by gathering pallet jamming on the rack stop peg. I would prefer a longer gathering pallet so until I make or buy one I have sleeved the stop pin so that the Gathering pallet sits more nicely on top.
The time train runs smoothly and all the levers lift and fall smoothly so most of the time the strike is fine.
But occasionally the strike doesn’t complete.
I watched whilst operating the lifting lever manually. The gathering pallet has a shuddering start, it starts to rotate then falters, starts again, falters and then continues ok. But does not continue ok and complete the strike every time.
The clock ran perfectly for years, but then developed this problem I fitted a new gathering pallet, new rack spring, rack tail, cleaned, polished to no avail. Left the clock for a few years quite frustrated by it all And having grandchildren!
This time I bushed three holes on the strike train, all run freely with good end shake and on assembly all ran well. Tried it in the case and it still has the problem.
I can see 4 potential causes .
1 the stop wheel pin has always been bent, but it ran with this for 25 plus years
2 The fly arbor is not parallel with the other strike train arbors, again ran for 25 plus years.
3 I replaced the base board as I was worried that it was too fragile, I followed the old, but feel that where bronze wire is tied off pulls the barrels to the side. Noticeable on the strike side.
4 the strike barrel rear hole was bushed but not the front (I can’t find the necessary broach) and it has some wear.
So I really want to get the clock going..... but cannot see why is strikes well nearly all the time and just occasionally doesn’t. I cannot run it as if it fails at 12 it will bend up the rack tail as it has done before.
I would welcome any advice or ideas. Please,as there are only 34 clock fixing days to Christmas!

 

[shutterbug]

3 I replaced the base board as I was worried that it was too fragile, I followed the old, but feel that where bronze wire is tied off pulls the barrels to the side. Noticeable on the strike side.

If the barrel is loose enough to be pulled to the side, I'll bet that's the issue. Also check the barrel cap for wear.

 

[Jim DuBois]

tallcase clocks don't have barrel caps.

 

[JimmyOz]

You said you did some re-bushing, before you did this, did you address the pivots, given the age of the movement I am sure they would have some ware.
If they look anything like the left pivot in the photo below they should look like the right pivot before bushing.

 

[gropa011]

Yes, nail tested, dressed slightly and polished. All seem fine. I have no lathe and do everything by hand except for very occasional Dremel use. So re-pivoting means atrip to the clock repairer! But I am very happy to do that when needed. I got the clock in 1975 and I have cleaned and oiled regularly. It surprises me how little wear there is on the clocks when they are looked after. This one has run 35 odd years and the bushes I replaced could have been done earlier, or could have waited a bit longer. I did them to eliminate candidates for the cause of the problem.
I have been thinking back to when this first started 10 plus years ago, I suspected the gathering pallet which was brass. Bought a new one but the pre-dilled hole was too large, bought another which fitted well after the hole was squared but the arm was not as long. However I thought I had eliminated the gathering pallet. Clock ran but the strike was still jamming occasionally. Tried a few things and crumpled a couple of rack tails! Not solved.
Last night I sleeved the rack stop pin with a larger Black Forest bush held on with white tack. Ran fine all evening. Open fire, glass of wine and the soft tick was great! I stopped it at 11:30 and restarted this morning. Ran ok. I will monitor carefully but am starting to think that the problem is the same as the OP Mark had. The first temporary sleeve was too small. I will make a new pallet anyway, this clock will eventually be for my son and I don't want to leave him (or anybody) a potential problem.
I will reroute the lines and looks like I have to buy another very large broach to bush the front barrel hole (as Shutterbug suggested). My wife fed up with me searching for hours has dropped heavy hints too! Annoying as I never used the one I can't find. Might even buy a pivot burnisher, but they seem really expensive £80 here in the UK).
I will update with progress! Hopefully!
Thanks for the advice I appreciate it!

 

[gropa011]

Just made a new gathering pallet. Took a nervous day, well it will when I finish polishing it tomorrow (tool marks)! To file the square hole I ground a small square file down so it had two cutting edges and two smooth. All seems ok so far, not tried it in case with weights yet. Bought another broach to replace the unused ones I lost/mislaid and smooth broach set for small holes. Will rebush worn strike barrel front and clean and oil. Again!
Then sort the base board out. I think I will make Christmas!
Here are a couple of photos. Does anyone thing the clearance is too tight, it's about a once folded cigarette paper?
Thanks!

 

[shutterbug]

The main thing is that it works. Let us know when you get it finished!

 

[gropa011]

No

Yes, nail tested, dressed slightly and polished. All seem fine. I have no lathe and do everything by hand except for very occasional Dremel use. So re-pivoting means atrip to the clock repairer! But I am very happy to do that when needed. I got the clock in 1975 and I have cleaned and oiled regularly. It surprises me how little wear there is on the clocks when they are looked after. This one has run 35 odd years and th kie bushes I replaced could have been done earlier, or could have waited a bit longer. I did them to eliminate candidates for the cause of the problem.
I have been thinking back to when this first started 10 plus years ago, I suspected the gathering pallet which was brass. Bought a new one but the pre-dilled hole was too large, bought another which fitted well after the hole was squared but the arm was not as long. However I thought I had eliminated the gathering pallet. Clock ran but the strike was still jamming occasionally. Tried a few things and crumpled a couple of rack tails! Not solved.
Last night I sleeved the rack stop pin with a larger Black Forest bush held on with white tack. Ran fine all evening. Open fire, glass of wine and the soft tick was great! I stopped it at 11:30 and restarted this morning. Ran ok. I will monitor carefully but am starting to think that the problem is the same as the OP Mark had. The first temporary sleeve was too small. I will make a new pallet anyway, this clock will eventually be for my son and I don't want to leave him (or anybody) a potential problem.
I will reroute the lines and looks like I have to buy another very large broach to bush the front barrel hole (as Shutterbug suggested). My wife fed up with me searching for hours has dropped heavy hints too! Annoying as I never used the one I can't find. Might even buy a pivot burnisher, but they seem really expensive £80 here in the UK).
I will update with progress! Hopefully!
Thanks for the advice I appreciate it!

 

[gropa011]

Accidental post above. Slow response stacked up button pushes! It didn't stop again, the rack hook lifted but the rack did not fall so no strike.
So after a frustrating few days the clock is running again. And striking.
So, noticed:
1 the minute wheel with the pin that lifts the lifting lever had lots of end play, always had. The retaining pin hole is 1.5MM from the end and not vertical and the pin was occasional fouling the snail at 12. Made a shim for the post so that the hole was vertical. Then made a collar to stop too much end float but that fouled too. Tried to profile for for ages but just so little clearance had to leave it as was. Explains why there was never a collar!
2 gathering pallet seemed to be too thick around the hole fouling the rack teeth. Filed slimmer and reprofiled the back.
Note that it ran and struck nicely for 8 hours like this, 16:00 to 23:30!
4 similar play on the rack which I had resolved 10 years ago with a loose collar. Soldered that on because I was fed up of dropping it and spending ages looking for it.
4 the snail also had a lot of forwards backwards play. Made a collar to reduce that. Pointless, can't fit it behind or in front!
Now to reveal the real problem!
5 the rack spring was loose in the "comma/tear drop'. This swivelled and pushed the rack against the retaining pin so it couldn't fall. Probably also pushed the rack off centre and reduced the clearance with the rack teeth.
Sorry for the long post.... Will fit the dial and post a picture in a couple of days.... Want to run it a bit first!

So learned a few things. I did bush all the worn holes and used my new smoothing broaches. I used the old baseboard with support, it bends alarmingly without. Will reinforce it more neatly after Christmas. Will also do some repairs on the case.
Thanks for advice and support, this had been a bit of a struggle! Merry Christmas!

 

[shutterbug]

The next one will be easier Glad you got it running!

 

[gropa011]

I sincerely hope so!

 

[Jim DuBois]

I have had a number of tall clock movements received from other shops/collectors/my own purchases that had un-resolved strike issues. For some reason, a lot of folks seem to think that strike problems can be corrected by hammering and filing on the rack, or in some cases reforming the snail by filing or soldering on pieces on steps where that clock is not striking correctly. These sorts of solutions seldom work, or if they do work, they usually don't work for long. I have had to make new racks as well as an occasional snail to resolve these prior fixes in some cases.

To the point, it seems rack and snail strike may work very well for a long period of time until wear finally overcomes design. Then, the strike train may well require several small repairs to work properly again. Sadly, those small repairs are often overlooked by Uncle Fix-it and the filing and hammering is quickly applied.

I have often found it necessary to rebush the rack arbor itself, also rebush the latch lever arbor, and also rebush the hour tube. Then there are gathering pallets with flags modified or they have been filed and shortened, or a piece soldered on. Then there is the tail on the rack itself. They are often the most cobbled up part of the clock. Most have been reformed multiple times, many have soldered on pieces, on and on. Returning all these parts to proper design tolerances can be both confusing and time-consuming. But absolutely required if you want it to work another 100+ years.

I have spent many hours on this Ives mirror clock movement getting the strike to work properly. I have had perhaps a dozen of those in here over the years, you would think I would have the process iced by now? Not the case. None of the dozen or so Ives had strikes working properly when they came in here. Adds a degree of credence to the 162 lawsuits place around these Ives mirror clocks in the NY court system extending for more than 15 years. Mary Jane Dapkus has documentation on all the suits and I think she will have a book out on Ives foibles very soon.

Both conventional American and English tall clock movements are not quite so demanding but still require some careful repairs.

 

[shutterbug]

It's always interesting to see what people can cobble up to make their clock work again. Nice job on the rack!

 

[Jim DuBois]

Thanks, I made that one as a demonstration. My claim was I could make a rack in two hours from raw sheet material. Some people thought that entirely impossible. I think it took me 2 hrs and 3 minutes. I did make one coffee run but I left it off and conceded I didn't make it in 2 hours. Nobody likes excuses.

 

[shutterbug]

LOL. I think coffee is a valid excuse any time

 

[gropa011]

So, put together in case with face attached. Ran well for a day, then no strike! Resoldered rack spring which had come loose , checked all clearances. Rack not falling every time
Finally reprofiled end of rack tail rounder. Made new oak support for base board, hide glued and clamped together so no bow and level.
Runs now and I feel confident.
Here is a photo. It's Abraham with his son....
Case next year!

 

[kinsler33]

Very good. And that picture will keep the kids in line.

M Kinsler