Sessions Strike Train Problem

[bikerclockguy]

Hey guys, I’m having a problem with the strike train on a 1920s vintage Sessions tambour clock movement. This one was especially feisty, but once I got the strike train timed correctly, another problem emerged, and I’m at a loss on this one. It moves through the count cycle smoothly for most of the count; strike lever drops in the center of the slot, and the train advances smoothly and evenly through most of the cycle, with 3 exceptions: 7:00, 11:00 and 12:00. On these cycles, the main and count wheel move in a herky-jerky fashion instead of a nice smooth advance, and the count lever seems to “smack” the bottom of the slots, and it almost looks as though that’s what is causing the jerky movement, although I can’t rationalize the count lever dropping with enough force to actually overpower the mainspring, even if only for a split second. There is an anomaly on the 11:00 strike that doesn’t happen on the other cycles as well. It “smacks” the bottom of the deep slot, takes a high double-bounce, and then the train advances. I’m fairly certain it’s not an issue with the timing, as it has been my experience that these problems usually manifest themselves most prominently in the short cycles, 1:00 and 2:00. I have run it through dozen or so cycles, and whatever the problem is, it’s consistent; smooth, even strike and stop on all but these 3 hour cycles. EDIT: meant to mention that the count skips and does not stop on these 3 hours.

 

[Vernon]

Maybe a lantern pinion issue? Slow it down with your finger controlling the fan to watch the operation.

 

[Bruce Alexander]

I see what Vernon is suggesting although the consistent 7,11,12 issue has me wondering.
Can you post some close up photos of the lower strike train and maybe a video?

 

[bikerclockguy]

Thanks, guys! Vernon, I will check the lanterns and see if I can spot any that are bent, and Bruce, I will try to get some pics and/or a video soon. We had a family medical emergency late last night, though, so I’m not sure when I will be back on it at this point.

 

[Bruce Alexander]

Hi Biker,

I hope everything is okay.
Got your Thread on "Watch". Get back to us when you can and take care.

Bruce

 

[shutterbug]

It's also possible that the relationship between the cam lever and the count hook is off. The deep slots are mostly for triggering the stop when the cam lever drops. If the count hook is hitting the bottom of the slot before the cam lever is at the bottom of the cam notch, the stop can't happen effectively. You might have to adjust the count hook a little higher to prevent that from happening.

 

[bikerclockguy]

Got back on this one late last night, and worked on it this evening as well. Turned out there were 2 issues; one was that I had not synchronized the count and drop levers exactly. When the count lever was bottomed in a deep slot, the drop lever was still a tooth shy of being completely seated in the cam slot. The second issue was with the count lever. When I put the movement together, I checked to see if the blade on the count lever was radial to the winding arbor on the strike train, and when I was satisfied it was, I didn’t inspect it further. On closer examination this evening, I discovered that it was bowed slightly, and the blade was also twisted slightly. I restrained the springs, loosened the plate nuts, removed the fly and locking wheel, fixed the count lever, and positioned all of the levers correctly. When I went to wind the movement and test it out, I discovered a loose click on the strike wheel, and in the process of trying to Jerry-rig it and make it work, I mangled the click spring pretty badly. So...I’m going to have to rivet my first click, and I have a couple of questions. I have a fairly good grasp of the procedure from recent threads, but I’m not sure what to buy. This kit says it’s for a Gilbert but will work on other movements, and it looks similar to the Sessions click setup. Gilbert Click/Rivet Pack. The original click is not in bad shape though, and I don’t know anything about the quality of any of these replacement, so I’m debating whether to buy that or salvage the original click lever and just buy packs of rivets and springs. Any thoughts on this?

 

[Bruce Alexander]

Hi Biker,

Good sleuthing on the Count Wheel set up. They can be a bit tricky but when everything literally falls into place, it's a joy to witness.

That click spring set up looks like it will work with a Sessions Clock. Are the springs steel or brass? Long-term, steel is better as it won't fatigue as quickly. The flimsy click/click-spring assembly is often the weakest link in a Sessions movement. If the original click isn't too mangled, you might consider adding the new click on a different spoke so that the two can work in tandem. I'm talking about a double-click set up. So far, I've done so on two Sessions movements. This was done on clocks that I sold and I've been happy with the results and an extra safety margin for the new owners. If the original is mangled beyond repair, I'd just replace it. One solid click/click spring has gotten the job done so far, right?

Good luck with it.

Bruce

 

[bikerclockguy]

The double click idea sounds like a good one, but if you do that, what do you do about the tab/cutout the end of the spring rides in?

 

[Bruce Alexander]

The double click idea sounds like a good one, but if you do that, what do you do about the tab/cutout the end of the spring rides in?

If you have a small rivet with a shoulder you could place one of those in an adjacent spoke to hook the click spring under. If you don't have one of those and if you don't have a lathe to fabricate one, you can place the 2nd click one spoke "behind" the original one and reach to the punched tab using it to anchor both click springs. That's not exactly an elegant looking solution, but if the new click's spring is long enough you can make it work. Just make sure that both springs are well anchored in the tab.