New Haven movement servicing

This movement came out of an unknown tall case clock that I am certain did not come out of New Haven’s factory. The case appears to have been made by an unknown case builder and I believe the movement, coil gong, dial face, and pendulum were all sourced from the New Haven Clock Company as a package, a kit, if you will.

The movement is a spring-driven count wheel time and strike commonly found in clocks for export. The chains are there for show. From the outside the clock may look like a weight-driven grandfather clock but it is clearly a fake!

Disassembly and assessment of work to be done

The movement is held together with five pins. The number 27 is stamped on the movement. Other makers stamped their movement with dates of manufacture but I don’t think that’s the case here. It appears to be the length of the pendulum in inches. A 27 inch pendulum corresponds to 4350 beats per hour or 72.5 beats per minute (BPM). Ordinarily, weight driven tall case clocks are 60 beats per minute, so this movement looks good running in the case and will fool the average person.

It has 9 extra holes on the front plate, obviously designed for a number of configurations. For example, there is an unused pivot hole to the right of the fan which would have accommodated a fan with a different sized 4th wheel, presumably for another style of clock case.

With the top plate removed the gears and levers are exposed. I found three anomalies.

  • One, there is an additional piece soldered onto the escape wheel bridge. Since there are no new bushings anywhere on the movement I can only assume that the bridge piece is the fix for a worn pivot hole.
  • The fly. I should have taken a photo. Two pieces of brass were jammed into the arbour which I assume was meant to tighten it. Flies are meant to be a little loose because they act as an air brake to help arrest the strike strain at the end of its cycle.
  • The third is the mainsprings. Try as I might I could not remove them from their arbours. I did not want to force them so, left them as-is. I immersed the gear plus mainspring together in the ultrasonic cleaner (not ideal) and used a hot air blow dryer to ensure the parts were dry.

Other than the above issues, there is not a lot of wear on this movement. The pivots are in great shape, with no wear evident on any of the wheel teeth, and the only pivot hole that must be addressed is the escape wheel bridge, the one that was “repaired”.

All parts were cleaned in the ultrasonic, dried and the pivots were polished. The movement was reassembled to check for general wear.

There is some pivot hole wear on the lower parts of the trains which, to me, is acceptable since all the gears mesh nicely. Since I am keeping the clock I am not concerned at this point. I plan on inspecting the movement every 2-3 years to determine if any bushing work might be required. So, I am content with a little wear.

Pivot work

One bushing was installed on the escape wheel bridge. I chose a 1.50 mm ID Bergeon bushing, 2.00 mm high with an OD of 3.5 mm. Since the pivot is 1.54 mm in diameter, the hole had to be reamed out with a cutting broach followed by a smoothing broach. While I drilled from the top (see below) I punched the bushing in from the bottom.

Escape wheel bridge

While polishing the pivots I discovered a bent arbour, the second wheel, which is also the strike wheel. Prior to servicing I checked out the movement on a test stand and noticed that the strike train would run for a period and stop. No doubt the bent second wheel arbour was the culprit.

The strike side mainspring is a replacement and a mainspring break likely caused damage to the second wheel. A broken mainspring does not always cause a problem but when they break a considerable amount of energy is released. As a general rule, if you are working on a movement with newer mainsprings check for damage up the train.

Bent arbour on second wheel

It is odd that the bent arbour was not caught when the mainspring was replaced. It is not hard to see the bend when spun on a lathe. It is always a risk straightening an arbour but since it is soft steel the chances of a positive result are very good. A staking tool was used to straighten it.

Using a staking tool to straighten and arbour

Assembly and testing

The movement was reassembled. I positioned the third wheel locking pin in the 12 o’clock position on the strike side to ensure the strike side would go into warning. I then synchronized the count and drop levers and managed to get it right the first time.

New Haven movement

Since this is a large movement with a long pendulum, a grandfather clock stand is ideal for testing.

New Haven movement
New Haven movement

The movement has been running a week as of this writing and striking as it should. I will continue to run it for at least two more 8-day cycles before returning it to its case.

Next is refreshing the case. It is very dirty with over 100 years of grime. I am curious to see what lies underneath multiple coatings of dirt.


2 thoughts on “New Haven movement servicing

  1. I recently purchased a wall clock that does not have main springs. I have no experience with this type of clock. It is driven by a weight on each side (2). I will need a special test stand . Any comment would be help full. Thanks Ron

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    1. I had to make a stand for a grandfather clock I bought in the past year. Check out this article. https://antiquevintageclock.com/2021/01/14/refinements-to-a-tall-case-clock-test-stand/
      To do anything other than a grandfather clock I would have to adapt a pulley mechanism to this design. If it is an ogee type clock you could do the testing in the case as I have done in the past. I have an upcoming article on clock stands that you might find interesting.

      Ron

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