Seth Thomas A101-000 electric movement

[daxelby]

Hi everyone!
I have a Seth Thomas A101-000 electric movement from a Baxter desk clock. I've identified a part that I can't figure out why it is used. There is a spring that goes around the center shaft about 1/8" from where the rear pivot goes into the hole. This spring looks like it's cut the center shaft arbor completely through. From the photo looking in between the two plates you can see the center shaft is severed. You can also see that there is another grove being cut, maybe the original cut then the spring was moved. Anyway does anyone know what this spring is used for? It seems like it could help with centering the asrbor but being so close to the pivot hole seems odd to me. Also the pivot hole is not sloppy. I plan to drill a hole in the end of the center wheel arbor and install extension to the arbor and pivot. Can't see why I need to use this spring again. However this spring is shown in Tran Duy Ly vol 2 page 1007 illustration.

 

[shutterbug]

It might be some kind of helper spring, but can't imagine that on that particular arbor. Could you install the surrounding wheels for us? Maybe that would make its function more clear.

 

[daxelby]

It might be some kind of helper spring, but can't imagine that on that particular arbor. Could you install the surrounding wheels for us? Maybe that would make its function more clear.

 

[daxelby]

View attachment 739211 View attachment 739212 View attachment 739213 View attachment 739214

It doesnt seem to have any interaction with other than the center wheel arbor.

 

[shutterbug]

I think it might be the tension spring used to allow the hands to move without moving the whole train. It's a strange way to do that, but no doubt it works

 

[daxelby]

I think it might be the tension spring used to allow the hands to move without moving the whole train. It's a strange way to do that, but no doubt it works

Well there's a tension washer on the center shaft like most clocks that allows you to turn the setting knob and move the hands without moving the entire train. This spring just straddles the arbor shaft like it's trying to center it but theres a pivot right there so that can't be it. Thanks for your thoughts though shutterbug.

 

[shutterbug]

Does it have a second hand? Could it be tension for keeping that moving smoothly?

 

[Mike Mall]

Just a guess - a vibration dampener - used to maintain some tension on the train and keep it from rattling?

 

[daxelby]

Does it have a second hand? Could it be tension for keeping that moving smoothly?

It does have a second hand and that is actually the shaft that was severed. I ended up drilling a hole in the severed end of the arbor then making a small extension that would fit into that hole. The other end of that piece was the xtension to the arbor as well as the pivot. Loctited the new piece into the arbor. didn't used the spring in question. Runs like a champ. I don't hear any rattleing but I guess time will tell. Thanks again.

 

[Mike Mall]

I bought and overhauled an ST Dynaire with the same movement last year. As a housewarming present for my step daughter's mantle.
It had similar wear on that arbor, though not nearly as severe.
I lubricated the contact area with my heavier weight synthetic oil after reassembly.
Hopefully it will hold up for many years, probably not another 70.
I assumed it was to prevent the 60hz buzz / humming when I serviced it.

 

[daxelby]

I bought and overhauled an ST Dynaire with the same movement last year. As a housewarming present for my step daughter's mantle.
It had similar wear on that arbor, though not nearly as severe.
I lubricated the contact area with my heavier weight synthetic oil after reassembly.
Hopefully it will hold up for many years, probably not another 70.
I assumed it was to prevent the 60hz buzz / humming when I serviced it.
View attachment 739580

Yep there it is! It's quite possible that was it's purpose though after installing the replacement piece and leaving that spring out I don't hear any 60 cycle hum. One of the issues I notice with mine was the spring was also severly corroded where it rubbed on the arbor. This probably exasperated the wear. Thanks for posting!