Catastrophic 2nd Wheel Trundle Failure

[MuensterMann]

I just finished a typical 1920ish German wall clock movement. All disassembly, cleaning, assembly, adjustment , etc went as planned. The movement was installed in the clock and all was adjusted. The mainsprings were wound and off it went tic toc-ing away. All was fine and dandy until about 6 hours later. It stopped. The time barrel could be spun freely. What? I noticed about 2 or 3 trundles broken off the 2nd wheel. Has this ever happened to anyone out there? Perhaps one trundle gave way and the momentum took out another one or two.

 

[bangster]

Perhaps one trundle gave way and the momentum took out another one or two.

My guess is that's right. Lotta torque at that wheel.

 

[Willie X]

This is a fairly common occurrence. The trundles are often cracked and then break whenever they decide to. Always check this part of the clock very carefully. I've seen some that have run a long time cracked. So long that they have become loose in their holes. I guess they crack due to what Bangs just mentioned.
Willie X

 

[shutterbug]

There is much information here about replacing trundles. Hopefully the trundles breaking saved the arbor from bending.

 

[wow]

Muenster, are you talking about cut trundles or a lantern pinion? If cut, do you have the equipment to make a new arbor with a cut pinion? If not, you may need to post photos and measurements and try to find a replacement or you could just send it out.

 

[R. Croswell]

The most common cause for 2nd arbor pinion failure is the sudden release of the main spring, either by the spring breaking or coming "unhooked", or failure of the click, click spring. or click ratchet wheel. The issue that may have caused the failure needs to be identified and fixed or the same thing will happen again after the pinion is replaced. That spring that checked OK before may no longer be OK.

RC

 

[MuensterMann]

RC, thank you for this input! Soon I will be investigating the health of the mainspring in the barrel. Then perhaps I can pinpoint the root cause and assess the overall damage.

 

[Dick Feldman]

In addition, whatever the failed train has been subject to in the last 100 or so years has affected the other train in that clock. The entirety of both wheel trains should be inspected for faults before putting the clock back into service.
The broken trundles on the second pinion may be only one indication of problems in that clock movement. You may find bad barrel teeth, bent arbors on the second or third wheels, and damage to corresponding pinions.
In your last post, you did not mention the clicks, ratchet wheels and return spring assemblies. Those may have been the root cause of the failure.

Best,

Dick

 

[MuensterMann]

I have inspected the barrel and its teeth; click; click spring, ratchet wheel; and all are in good shape. I held the barrel and gave it a few winds that I could hold in my hand - and the mainspring was not broken or disconnected.

I removed the 2nd wheel and three trundle pins were missing and the pinion was not bent. Above the middle missing trundle pin (or where it was) there was a hole such that a trundle pin could fall out. The trundle pins are held in the assembly with a layer of solder (it looks like solder). There was a hole in the solder holding the middle missing trundle pin. See image below.

Not sure of the exact root cause, but it seems that (at this point) the failure was due to the pins breaking. Perhaps one failed and the force broke the others. It may be that the one pin fell out and the force of the barrel (the teeth) gained momentum to take out the next one. The barrel may have spun freely and the other end pin got in the way - thus it took it out as well.

Some facts and some theories!

 

[Dick Feldman]

Hmmmm,
I'd bet you check every movement you take apart from here on.
Good luck,
Dick

 

[shutterbug]

It has clearly had a pinion or two replaced before. Maybe they didn't do a very good job, and some slipped out due to being too short.

 

[R. Croswell]

If the trundles actually broke - snapped into two or more pieces - it is likely that they are replacements that were hard and brittle. I would replace all the rundles in that pinion, remove the solder and stake the openings to retain the new trundles. I agree with Dick, inspect the other 2nd lantern pinion as well and if it has solder, replace the trundles there as well.

Unusual for a main wheel to spin free and rip out trundles without receiving some damage to the main wheel teeth. Also, just because the main spring accepts a few hand-held turns does not guarantee that all is well. Sometimes a mainspring can slip past the pin on the winding arbor when the spring is fully wound but feel like it is holding in your hand. If this were my clock, I would want to remove that main spring and have a look at the pin on the arbor. It probably could use a cleaning and oiling anyway.

RC

 

[MuensterMann]

Yes, I do realize that perhaps one more half turn I could feel the slip - so yes that is still a possibility. I found one whole pin, and what seems to be half a pin at the bottom of the clock. So, not all pins are accounted for.

So, the solder technique that was done in the past is not a good method and should be avoided?

"To stake" the openings. What is meant by this verb? Does it mean to close the opening by deforming the hole?

 

[R. Croswell]

Yes, I do realize that perhaps one more half turn I could feel the slip - so yes that is still a possibility. I found one whole pin, and what seems to be half a pin at the bottom of the clock. So, not all pins are accounted for.

So, the solder technique that was done in the past is not a good method and should be avoided?

"To stake" the openings. What is meant by this verb? Does it mean to close the opening by deforming the hole?

A search for lantern pinion repair should turn up examples. Make a punch with a small rectangular end that is wide enough to bridge the hole. Strike the punch to leave a mark that forces some metal into the hole to lock the trundle in place. You need to support the shroud with a split stake or crows foot.

RC

 

[shutterbug]

Some people use solder, and some use LocTite ... but neither of these options are kind to the next repairman. Staking is the proper way, or Knurling if you have the equipment to do it. Any kind of adhesive, including solder, eliminates any possibility of the trundle turning in the shroud. If it can turn a little, it slows the wear considerably.

 

[MuensterMann]

Perhaps solder was used to cover the hole to prevent the pin from coming out - as opposed to soldering the pin to the hole.

Anyway, I did find one tooth slightly bent barrel wheel. Not bad. I put the 2nd wheel on a lathe to discover that the arbor was slightly bent. I heated up the solder to see if I can get it to flow, but for some reason it did not flow. I may have to rid the surface solder by turning it on a lathe and then drill out the remaining trundle pins.

After putting in new trundle pins I may just press a steel washer above the trundle holes to seal the pins in. At least that is what I am thinking today.

 

[MuensterMann]

As for the mainspring, it is still good. No problems. Grabbed a leather glove and would it almost completely - and no slips.

 

[R. Croswell]

Perhaps solder was used to cover the hole to prevent the pin from coming out - as opposed to soldering the pin to the hole.

Anyway, I did find one tooth slightly bent barrel wheel. Not bad. I put the 2nd wheel on a lathe to discover that the arbor was slightly bent. I heated up the solder to see if I can get it to flow, but for some reason it did not flow. I may have to rid the surface solder by turning it on a lathe and then drill out the remaining trundle pins.

After putting in new trundle pins I may just press a steel washer above the trundle holes to seal the pins in. At least that is what I am thinking today.

Turning the shroud in your lathe to remove the solder is one good way to remove the solder. Heating the pinion to the solder menting temperarture and blowing with compressed air also works. There should be no reason to press on a steel washer. Once you have the shroud cleaned up and the new trundles in place, just stake each hole to keep the trundles in place and turn in your ticket to the Hall of Shame for a refund.

While solder looks crude and is generally not considered a proper method, it is often the flux that does the damage. Soldering steel requires a corrosive flux that seeps into any tiny crevice where it is next to impossible to completely remove. What looked like a "clean" solder job in a couple years is often the site of rust and corrosion. In many cases it takes less time to do the job right in the first place.

RC