• 11 40 (November 1940) on left rear movement leg;
• 4506 (June 1945) on strike hammer bridge.

I can’t explain why there are two date codes, perhaps they made the movement before World War II, then finished and sold it after the war (they discontinued clock production for several years during the war). (Note: the owner of this clock states that it was bought during the war. This would mean that the 4506 is not a date code, perhaps it is a model number?)

The case is 8 5/8 inches tall and 12 3/4 inches wide. The dial is silver plated brass, with printed numerals, etc. The minute hand is 2 1/2 inches long from center to tip. The hands and hand nut are silver-plated. The minute track is 5 inches outside diameter. The movement runs over 8 days on a winding and strikes the hours and half hour on 2 chime rods.

See more photos.

This clock has Seth Thomas’s later type of mantel clock movement (the one that replaced the No. 89). In the past, I didn’t like this movement, because it is subject to severe wear due to its overly strong mainsprings. I have discovered that it will run well with weaker mainsprings (see 1940s Seth Thomas 8 Day Time and Strike Clock Movement for another example of this movement, and Two Seth Thomas “Plymouth” Tambour Mantel Clocks, 1938 and 1945 for another example).

This movement has suffered wear (see photo of the worn bushing above). A previous repairer installed many bushings off-center. It appears that first, off-center rear mainwheel bushings were installed, then all the other bushings were installed off-center to keep gear depthing correct. I tested all the gear depths, and left the bushings off-center except for one that needed moving. The rear time second wheel pivot was rough (the surface was like a fine file), which is why there was so much wear to its bushing. I polished all the pivots and replaced a bent wire in the center pinion.

I replaced the too-strong original mainsprings with weaker ones.

Original mainsprings:

• Time 11/16 x 0.0183 x 80 inches;
• Strike 11/16 x 0.018 x 80 inches.

New, thinner mainsprings:

• Time 11/16 x 0.0161 x 80 inches (Timesavers 20506 shortened by 16 inches);
• Strike 11/16 x 0.0167 x 80 inches (Empire Clock 280-17-505 shortened by 16 inches).

(Note: supplier Empire Clock is no longer in business.)

The movement runs extremely well these mainsprings, and would probably run well with even thinner springs (perhaps 0.015 inch thick for the time mainspring). Both mainwheels are 25% worn due to the original strong mainsprings. The clock runs well in spite of the tooth wear.

The pendulum bob is 1 13/16 inches diameter and weighs 4 ounces. The suspension spring is 0.004 inches thick, and the pendulum rod is 2 millimeters diameter.

The inside of the rear door has an instruction label. The label includes the following:

Guarantee and Directions
Covering Clocks equipped with
No. 4300, 4500 and 4600 Series 8-Day Pendulum
Strike Movements in Tambour Cases.

Text here about the clock

Instruction text here

The Plymouth Clock
Thomaston, Conn.
Z-34P

The number 414 is stamped at the bottom.

Repair job 5534

Key: No. 6 large end, No. 0000 (4/0) small end.

The case is 19 3/4 inches wide and 9 1/4 inches tall. The dial has a 4.5 inch time track, and is aluminum with embossed and painted numerals.

The movement has the original mainsprings that still open up very far and provide plenty of power. They are 3/4  inch wide loop end springs. The thicknesses are:

Time mainspring: 0.017 inch

Strike mainspring: 0.0167 inch

Job 5146. I had last repaired this clock over 10 years ago, and it just needed to be disassembled and cleaned to make it run well again.

Plymouth was a name that Seth Thomas put on some clocks ca. 1930 – 1950. If anyone has details of this, please let me know.

Our first example is labeled 89IM on the movement. This is a variation on the popular No. 89 movement having hour and half-hour strike, with two hammers that simultaneously strike on two chime rods. The date code is 37-11 which represents November, 1937. The label on the back door has the date 5/21/38 (May 21, 1938) hand written on it. This is probably the date the clock was sold.

Our second example has the later Seth Thomas time and strike movement that was introduced to save on cost. It is labeled 10-40 and 4503, which could be date codes for October 1940 or March, 1945. If anyone can help me interpret these numbers, please let me know! Similar movements have been seen with model number A-200 on them. The label says:

Guarantee and Directions
Covering Clocks Equipped With
4300, 4500 and 4600 Series 8-Day Pendulum
Strike Movements in Tambour Cases

Both cases are 20 inches wide and 9 1/4 inches tall, with bezels measuring approximately 6 1/4 inches outside diameter. Both have “fake inlay” printed on the case front. Both  have aluminum dials. The older dial has embossed numerals, but the numerals on the newer dial are printed only. Both clocks have instruction labels inside the back doors and are illustrated below.

Movement Summary

• The No. 89 movement was introduced about 1900, and was made in many variations.
• It was replaced in the late 1930s or the early 1940s with the second movement shown above. This has smaller plates and gears and was probably a cost reduction. It is not as good, as it seems to need quite strong mainsprings to run well.
• In 1955, a flood badly damaged the Seth Thomas factory. They phased out movement manufacturing and began importing many movements from Germany. They used many Hermle movements.