Troubleshooting A Strike Issue on a HAC/HAU Movement

The maker of the movement is HAU or HAC. The familiar cross arrows trademark of the maker is stamped on the movement, in the middle of the backplate.

HAC was formed in Germany in 1873 by Paul Landenberger and Phillipp Lang and was originally called Landenberger & Lang Uhrenfabrik. The company changed its name to Hamburg Amerikanische Uhrenfabrik (HAU)/Hamburg American Clock Company (HAC) in 1883. The famous crossed-arrows became their trademark in 1892. In 1926 the company went into a cooperative with Junghans and in 1930 they finally merged with Junghans.

HAC/HAU clocks can be difficult to date prior to Junghans acquisition of HAC/HAU in 1930. Once Junghans and HAC began their collaboration in 1926 some of the movements were date coded.

Now on to the adjustment of the movement that is the subject of this article.

Strike Adjustment Required

Earlier in the fall this time and strike mantel clock was serviced. During the servicing six new bushings were installed, all components were cleaned, the mainsprings serviced and the clock reassembled and tested.

_{The movement has been cleaned and serviced}

However, during testing, the movement did not strike correctly. While there can be several causes, the most common of which is a misalignment of the hammer tail with the star points on the star wheel. This issue frequently arises during the reassembly of this type of clock movement.

Taking the time to carefully double-check the placement of parts, and ensure everything is in its correct place will help ensure the reassembly is smooth and successful. Once the wheels are in place there is only one multi-arm ever that resides between the plates. Position it such that the long arm rests in one of the deep slots of the count wheel while a short arm is placed in the cut-out of the cam wheel.

My usual practice is to position all the wheels and the lever(s) on the plate that has the movement posts, first. Once the wheels are correctly located, I lower the front plate onto the back plate. I secure two nuts to the mainspring end which prevents the movement plates from moving around as I position the upper wheels and their pivots in the train.

Setting up the strike side can be tricky. The wheels and levers must be set up correctly or the strike will not function. For instance, the width of the slots on the count wheel tells us that there is no “passing strike” on this movement. In some count wheel movements, for example, in many American-made movements, the half-hour is actuated by a cam on the centre arbour.

The pin-wheel, which is uppermost and one wheel removed from the fly on the strike side, is placed in approximately the 10 to 12 o’clock position, called the “warning” position. This allows for a half-turn to set up the strike.

To make the adjustment of the star wheel there is no need to completely disassemble the movement. Loosen the nuts on the strike side and gently lift the plate taking care not to dislodge the wheels on the time side. Disengage the star wheel from the adjacent wheel and rotate it slightly so that the hammer tail is in the middle of two of the star tips.

_{Tail and star point (arrows), in this photo, the tail is almost resting on the star point which is not the optimal position}

The adjustment was made. On the test stand, the hammer tail isn’t perfectly centered between two of the star points, but it should function adequately.

If the hammer tail is in contact with the star point at the end of the strike sequence, it will hold in the raised position and the strike may not function at all from that point onward. While you are making this adjustment, ensure that the strike lever spring (which is a straight wire) is on the outside of the strike arbour.

In Sum

Adjusting the strike mechanism on an HAC movement requires patience, precision, and attention to detail. By carefully aligning the hammer paddle, star wheel, and other components, you can restore the clock’s striking functionality and ensure reliable performance. While challenges such as this are common when reassembling these movements, a systematic approach and an understanding of the mechanism’s function can make the process smoother.

January 28, 2025 0

Hamburg Amerikanische Uhrenfabrik | Servicing an 8-day Countwheel Strike Movement – Part II

I am currently working on a mantel clock from the Hamburg American Clock Company. This is Part II in a two-part series. For Part I go here.

The Hamburg American Clock Company is otherwise known as Hamburg Amerikanische Uhrenfabrik or HAU and in many parts of the world, it is simply known as HAC.

In Part I, I described the steps taken so far which are disassembly, inspection, cleaning of the parts, and polishing of all pivots. The next steps are bushing work, reassembly, oiling (the mainsprings were oiled in a previous step), and finally, testing.

I believe this is the No. 36 movement by HAC.

The wheels that spin the fastest typically show the most bushing wear, but wear can also appear in other areas, such as the main wheels, which endure significant torque. For instance, I observed punch marks on the cap side of each mainspring barrel. While punching around any bushing hole is generally poor practice, it appears this was done at some point in the clock’s history and can’t be reversed. Nonetheless, the repair seems to have held up well.

Bushing Work

I have seen similar movements with much more wear than this one, but I felt that some bushing work was necessary to extend the clock’s lifespan.

Six Bergeon brass bushings were installed in total. For the time side (T), bushings were placed at T1 (front and back) and T3 (back). For the strike side (S), bushings were installed at S3 (back), S2 (front), and S4 (front). The numbers indicate the wheel location in the train beginning from the bottom. A couple of pivot holes were borderline, but I decided to leave them as they are.

Reassembly

It pays to be patient and methodical during reassembly. Rushing can lead to mistakes, such as missing steps or improperly aligning parts, which could cause malfunctions or even damage later. Taking the time to carefully double-check the placement of parts, and ensure everything is in its correct place will help ensure the reassembly is smooth and successful.

_{An older HAC movement, without the barrel cutouts}

Once the wheels are in place the lever and there is only one multi-arm ever that resides between the plates. Position it such that the long arm rests in one of the deep slots of the count wheel while a short arm is placed in the cut out of the cam wheel (as above).

Positioning the pivots is a delicate process, and any forceful handling can result in a bent or broken pivot. In this, as in all cases when aligning pivots, a pivot locator is your best tool.

My usual practice is to position all the wheels and the lever(s) on the plate with the movement posts, first. Once the wheels are correctly located, I lower the front plate onto the back plate. I secure two nuts to the mainspring end which prevents the movement plates from coming apart as I position the upper wheels in the train.

The pin-wheel, which is uppermost and one wheel removed from the fly on the strike side, is placed in approximately the 12 o’clock position, the warning position. At the same time the hammer paddle is positioned between two of the points on the star wheel. More than once I have had to go back in to make minor adjustments when the paddle hangs up on one of the star points. It looks like this one is also a candidate for that very adjustment.

_{A Timetrax machine is used to adjust the beat and the rate of the movement.}

The movement has been placed on a test stand and the time side Is in beat and running as it should according to my Timetrax machine. Curiously, the Timetrax manual lists only one HAU/HAC movement, a three-train one but this one is likely similar to Junghans bracket clock movements which runs at 164 bpm. Junghans is mentioned for comparison because, by 1930, the company had successfully taken full control of HAC.

Testing

The testing phase is crucial in the process of servicing a clock, often taking the most time because it ensures that the clock is functioning properly before it is reunited with its case.

During this phase, the clock is put through various operational checks to simulate real-time performance, which helps in identifying any issues that may not have been apparent during the initial servicing or cleaning process. Issues such over-tightened or loose components can present themselves as well as problems with the escapement mechanism.

The testing phase serves as an important diagnostic step to identify what further repairs or adjustments may be needed.

This concludes the servicing of an 8-day HAU/HAC movement. If you have any comments or feedback on any of the steps in the process, please feel free to share!

October 1, 2024

Servicing a HAC Clock Movement

Among clock collectors and admirers, the Hamburg American Clock Company is a well-known German company. It is otherwise known as Hamburg Amerikanische Uhrenfabrik or HAU and in many parts of the world, it is simply known as HAC.

In this post, I will outline the procedures involved in servicing the movement of a HAC mantel clock produced circa 1925. It’s worth noting that HAC crafted clocks for international markets, and in the case of this particular clock, it spent a period in England after its initial manufacturing.

_{Time and strike mantel clock made by the Hamburg American Clock Co. known as HAC or HAU}

Disassembling the movement

After removing the clock hands and releasing the six screws that attach the movement to the front dial board the movement can be maneuvered carefully around the bronze rod gong without having to remove the gong itself.

Once out of its case, the first step is to remove the suspension spring and pendulum leader. A taper pin secures the spring onto the suspension post.

Next, safely let down the mainsprings using a letdown tool. On this movement, and I have not seen it elsewhere, there is a small pin on each rachet. Once the letdown tool is placed in the arbour, it is a simple matter of pushing the pin on the click with a small screwdriver and allowing the rachet to run freely, under control, of course.

The pin on the click is indicated by an arrow — _{The pin is indicated by an arrow}

At this point, the two exterior wheels, both rachets with their retainers and the click springs can be removed as well as the “V” shaped stop lever.

On the front of the movement, two screws hold the pallet arbour plate, and with it comes the crutch. Note the position of the small pallet arbour plate for future reference. This is also a good time to remove the hammer from its arbour but the plates can be separated with the hammer still attached.

At this stage release the 4 nuts holding the movement and the back plate can be removed. There are two springs which look like stiff wire, one is for the count lever and the other for the hammer. Do not break these springs and be careful handling the plate once it is separated. The wire springs can be repaired if they break but it adds more work to servicing.

Plate is removed exposing wheels and levers — _{Plate is removed}

Once the plate is lifted from the movement, the wheels and levers can be removed. Strike and time side wheels are then separated into containers. I like working from the top down and carefully removing each wheel one at a time. The centre cannon is the last wheel to be removed. The half-hour cam, a star wheel with two points, is on a tube which can be pulled off the arbour and the centre wheel easily lifts out. Once the centre cannon is removed the mainspring barrels can be extracted and put aside for servicing.

Assessing wear

Identifying whether a movement has undergone previous work can be challenging, but scratch marks around pivot holes typically suggest past work. An unmistakable sign of prior servicing is the presence of punch marks, as observed around the mainspring barrel on the time side. The aggressive punching suggests that the arbour hole was enlarged considerably. However, the arbour’s fit through the barrel appears sufficiently tight, indicating no immediate concern.

_{Time-side mainspring barrel showing punch marks}

While it’s not approved today, punching pivot holes was a common practice in the past.

The movement is relatively clean but over-oiled the result of simply lubricating the clock over the years without actually checking to see if it required new oil.

There are very few issues with the movement with a potential need for two new bushings on the strike side and just one on the time side.

Cleaning the movement parts

Cleaning a clock movement’s parts is a fundamental step in the maintenance and restoration process. It not only improves the immediate performance of the clock but also contributes to its long-term durability and accuracy.

Cleaning a mechanical movement’s parts before reassembling a clock movement is crucial for several reasons, to remove dirt and debris, prevent wear and damage, optimize performance identify and any perfomance issues. Cleaning is often accompanied by the application of fresh lubrication to key components. Lubrication reduces friction between moving parts, minimizing wear and ensuring smoother operation. This step is vital for maintaining the health of the movement.

March 19, 2024

Dating a Hamburg Amerikanische Uhrenfabrik (HAU) shelf clock

During the Christmas season, we split our time between Calgary, Alberta, and Ottawa, Ontario to see our 2 daughters. While in Calgary my wife spotted an interesting item on an Ottawa Facebook Marketplace, an English time and strike clock.

She showed me the photo and I said, “that does not look like any English clock I am familiar with. The style is definitely German”. There is a commemorative plaque on the front base section which references an English church so, I am assuming the seller thought it was English.

When we picked it up from his home outside Ottawa I was surprised to learn that the seller is a clock collector and had no idea the clock he was selling was German. Occasionally I sell clocks to manage my collection and when advertising one for sale I make it a point to know the maker.

But, no matter, it was in very good condition and in working order.

_{The movement showing the single strike rod and pendulum bob}

The maker is HAU or HAC. The familiar cross arrows trademark of the maker is stamped on the movement, in the middle of the backplate.

became their trademark in 1892. In 1926 the company went into a cooperative with Junghans and in 1930 they finally merged with Junghans.

The date on the plaque says 1926. However, HAC/HAU clocks are difficult to date prior to Junghans acquisition of HAC/HAU in 1930. Once Junghans and HAC began their collaboration in 1926 some of the movements were date coded.

Plaques are a good but not foolproof method of dating a clock. A clock purchased as a gift in 1926 could very well have been sitting on the retailer’s shelf for two or more years.

Catalogs are another good but hardly foolproof method of dating a clock. A catalog confirms that a model was made in a particular year, but that same model was probably offered 5 years +/- from the year of the catalog.

I will probably not determine a more reliable date for my new clock than circa 1926. The movement, compared to an earlier model (below), also has many cutouts and additional holes that indicate that it was a late production model and confirms that is closer to the 1926 date.

The clock runs for a while and stops. It is in need of a service but I expected to clean it as many of these old clocks have rarely seen the inside of a clockmakers’ shop.

February 4, 2022

Strike Adjustment Required

In Sum

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Bushing Work

Reassembly

Testing

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