Seth Thomas Clock Movement

Seth Thomas Clock MovementST IdentificationHow to Order STWhy Order STMovement IssuesHistorical Timeline

Please view these information tabs for assistance, there is important information needed for a new Seth Thomas Clock Movement.

Seth Thomas movement identification

Seth Thomas clock movements have identification markings. What made this name so famous is back in the Antique days they made there own movements and there own clock cases and the quality was astounding. After the war era they did not make any clock movements anymore but did use Hermle clock movements.

In the end

The Seth Thomas name has been tossed from one company to the next after the war. The short version of these take overs is we are left with three types of Seth Thomas clock movements. The Antique Seth Thomas that produced so many clocks during and long before WW2. Then we have post WW2 Seth Thomas using the German units such as Hermle or Kieninger. In these modern times the name can be found usually on battery operated clock dials. This is what we are offering here at Hermle is an excellent quality German made movement for the modern world.

Is the clock an antique Seth Thomas?

How to tell if the ST is Antique can be done a few ways. The easiest way is if the movement has no pits in the movement plates. Please see the below picture and notice the pattern on the outer plates. The antique Seth Thomas clock movements never had this design pattern on them. It will have ST with a circle around it for a logo. The movement will say made in USA and may have a few numbers on it such as 89 or 124. This will tell you it is an antique, not available new, and made before 1950.

Seth Thomas Movement Identification

Modern ST identification

The picture displays what is meant by small bumps in the movement plates. So if this sort of design is on the Seth Thomas clock movement it indicates some interesting things. The movement was produced between 1950 and 1979, and it was made in Germany. This also means you have a good chance of getting a new movement for the clock from To get the new movement would mean to spend a fraction of the price of an overhaul and ships right out. The clock will be fixed right away instead of months later. It is not possible to overhaul a clock movement so it is better than new. To get the exact same movement brand new, it gets matched up on the Seth Thomas page.

The content of this website is copyright by Clockworks and written by James Stoudenmire

German Seth-Thomas Clock Movements

German Seth-Thomas clock movements are still available. Finding a new movement starts with the identification numbers off the back plate. The numbers need to be converted because they did not make any movements after 1950. Instead they were made by Hermle of Germany with the ST number system and ST name instead. So really its a Hermle in disguise and ST only marketed the clocks. The used the Seth Thomas name on the Hermle movements and married them to its clock case.

How to order

The first step in replacing a >Seth Thomas clock movement is to get the numbers off of the back plate. If it starts with the letter A such as A401-003 then it is a ST number and must be converted. Find the number in the list and get the new number and write this number down. After writing the number down click that converted number to get to the right movement. will ask you what options are needed and this is when you refer to the number you wrote down.

Do not completely trust the chart

The above instructions work as a guide only. This chart unfortunately is often wrong and is only used as a basic guide to what series the movement is only. The rest of the attributes it is best to double check the accuracy such as CM lengths and hand shaft lengths. Please email us with the ST number information so we can verify the charts accuracy. Our email address is [email protected] and we would love to help.


Getting the new movement is better than even the best repair. These are 25 year movements and Seth Thomas was gone over 40 years ago.

The content of this website is copyright by Clockworks and written by James Stoudenmire

New Seth Thomas Movement

A New Seth Thomas Movement can ship the same day you order it. The new movement (if available) will cost less than a cleaning and overhaul of the old unit. It will last much longer will be up and running in your clock in a week instead of months down the road.

The new movement

What is being offered is the same movement you have now but new. The same movement, not some knock off replacement or made by someone else. The modern Seth Thomas clocks were produced by manufacturers other than Seth Thomas. It will have their name on the movement to say that they designed the clock and its case, but they did not make the movement if the clock was produced in modern times (post 1950).

Which ones can be replaced verses repaired

It is a simple and obvious fact the new one is better than chasing the old one. With the cost savings and life expectancy tripled its an easy choice. When the Seth Thomas clock is made prior to the end of WW2 its a different story. Those are no longer made but you can send us the movement only, we do the best restoration.

The content of this website is copyright by Clockworks and written by James Stoudenmire

The Broken German Seth-Thomas Clock

Repairing the broken German made Seth-Thomas clock by replacing the movement with a new one. Seth-Thomas went out of the clock business as of about 40 years ago. The movement has lived its long after its life expectancy of 25 years just by having the name ST. The Seth Thomas from WW2 and prior used American movements, but after 1950 used German made units. So they did not make any movements themselves after the 1950 date, instead they were mostly made by Hermle. The Hermle clock movement is alive and well, so the movements are still available.

What happened to the old one

After 25 years the oil becomes a solid instead of a liquid. This will cause too much resistance in the movement for it to run and it will end up a not working. Just having the name Seth Thomas on the clock means it is about 40 years old at best. There are two choices if saving the clock, restore the old movement or get a new one if possible. The choice is an obvious one, the new unit costs a fraction of the price of restoration. It ships today instead of waiting up to 6 months for the restoration to be completed. A new one will last another 30 yrs without much complaint.

After 25-30 years this happens

Why does age effect the operation of the German clock movement? The clock oil that is put on the movement back when it was new, has solidified with age. What was once a lubrication to the Seth Thomas movement has now turned to a sticky black abrasive substance. This creates both resistance and wear on the movement and it ends up broken. This wear and resistance will ultimately stop the clock from functioning properly because the pivots that ride in the holes of the movement's brass plates will not be able to spin as freely as they did in the past. The holes have become oblong instead of round so the pivot is pinched inside of the hole that it's supposed to spin inside of, and the oil is an abrasive rather than a lubricant.


So now you see the choice is pretty clear. The new movement, when available from is the best choice by far. The movement will be the same movement for a fraction of the price, brand new, oiled, tested, and last decades longer than even the best restoration. The broken German made Seth-Thomas clock can be back up and running in a week.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Seth Thomas Historical Timeline

The Seth Thomas factory made countless clock movements during and prior to the second world war. The high quality standard made the company a great success. After the war they stopped making any movements and used alternate makers. The out sourced movement makers produced them for there Seth Thomas clocks cases.

Start of German made movements

So the clocks were Seth Thomas but the clock movements were made in Germany instead. The German movements used by Seth Thomas were made by Hermle clock company or Kieninger. Seth Thomas only married them to these units to the clock cases and sold them under there company name.

A long History

The Seth Thomas had a long history of clock making. The name ended up being exchanged from one company to the next through the years, and is now extinct.

Seth Thomas Historical Timeline


Seth Thomas starts in Wolcott, Ct by James Thomas.


James Thomas begins working with Eli Terry as a clockmaker apprentice near Waterbury, CT. Because Terry got an order to make 4,000 clocks.


James Thomas opens his own Seth Thomas shop in Plymouth Hollow, CT.


Seth Thomas starts using brass clock movements which they used in Ogee Clocks.


Seth Thomas Clock Company is incorporated


Death of Seth Thomas, now run by his three sons, Seth Thomas, Jr., Aaron, and Edward.


The town of Plymouth Hollow changes its name to Thomaston in honor of Seth Thomas


Seth Thomas Watch Company is established


Seth Thomas Clock Company becomes part of The General Time Instrument Company by the great grandson of Seth Thomas


The Thomas family no longer controls The General Time Instrument Company


Seth Thomas Clock Company becomes part of General Time. This is the start of all those electro-mechanical clocks with the wooden cases.


General Time becomes part of Talley Industries. This is when they were using German movements made by Hermle, Kieninger, and Urgos.


General Time ends and Colibri buys the assets of Seth Thomas


Colibri Group discontinues all business with clocks

End of Seth Thomas Historical Timeline

End of Seth Thomas

As you can see, the Seth Thomas Clock Company had a long run and a wild ride. The company name may now be found on silly things like lighters and some quartz clock dials. What we offer and sell is the German ST units made in Germany. These are the units General Time and Tally Industries sold under the Seth Thomas name they owned, and put Hermle clock movements in the clock cases. These German units are high quality and last 25-30 without much complaint.

The content of this website is copyright by Clockworks and written by James Stoudenmire
Seth Thomas Logo

Seth Thomas Clock Movement OLD Number / NEW Movement Number
Please note, this list is often WRONG and is only a basic guide.

  • * Rear Pendulum Seth Thomas clock
  • ** Front or Rear Pendulum Seth Thomas clock
  • *** Needs new pendulum with it. Need to reverse direction of chimeblock.

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