Tower Clock in Glashütte Part 2

Since its name was first mentioned, the protestant city church St. Wolfgang was repeatedly modified. Since 1936 it accomodates a tower clock mechanism of Zachariä from Leipzig, which showed the time on its blue outer dial until September 23rd, 2019.

Find our more about our wrist watch “tribute to the tower clock” of Glashütte.

A foray just before the renovation of the church in 2008

The old wrought-iron church tower clock was in service until 1936

Before the refurbishment of the Glashütte St. Wolfgang’s Church, we had the opportunity to see the clocks of the church as well as the old lute machines in spring 2008.

On one afternoon we arranged to meet Mr. Rahm at the Glashütte church. In the article of Richard Lange in the “Deutsche Uhrmacher-Zeitung” reference is made to the old wrought-iron church tower clock, on which Adolf Lange had a long pendulum installed. He tested the higher accuracy when using long pendulums before constructing his house clock. We wanted to see that on our self.
Mr. Rahm greeted us in front of the entrance and led us to the gallery.
In the Glashütte church, a wrought-iron clock was in service until 1936. The movement had previously moved the hands of the Johnsbach tower clock. It now replaces the simple movement without dial, which only told time with the sound of bells.
The “new” used clock received a wooden dial around 1840 and was later fitted with a hitch escapement by the council watchmaker Louis Müller. At that time, this was a common measure to improve the accuracy of the old movements, which mostly had verge escapements. In the Glashütter clock, however, a smaller escape wheel was installed. The reason for this was Adolf Lange’s idea to further improve the accuracy of the pace through a particularly long and heavy pendulum. Lange was also mayor of Glashütte from 1848-66. So he suggested making a 2.5-second pendulum for this watch, which was then over 6m long.

Clockwork, pendulum and wooden dial still exist today. Mr. Rahm brought the pendulum pole to the gallery.

It consisted of a 5cm thick log stick with a planned surface. Unfortunately, the pole had been cut in the middle and is currently connected with two tabs. The reason was misuse as a handrail on the stair railing, which also meant that a piece was missing. It was painted black (which might have been the original color) and had heavily rusted and grey-coated iron fittings at the ends, which were connected to the rod by lateral wooden screws. The upper one was a massive double hook with a round frame, in the lower one the rod ran out in a rectangular cross section. On the threaded spindle was the wide, flat nut attached at the end.

Now we climbed the narrow spiral staircase to the tower with Mr. Rahm.
in the tower on a window sill in the anteroom of the clock lay the pendulum lens which was separated from the pendulum rod. It was made of cast iron and still in its original condition, diameter was about 30cm and a continuous rectangular opening for the pendulum rod.

The wheels were somewhat restored by Mr Sauerwald in 1983, although unfortunately the wooden rollers were also painted with silver bronze. Despite all the criticism, it must be noted that this preparation may have saved the clock from scrapping, but in any case prevents further rusting. The beautifully forged clockwork with three pulleys is still exhibited in the nave in a glass display (which no longer exists). On the wall behind is the old wooden dial. Its Roman characters are very artistic and harmoniously drawn.
Apparently, the clockwork lacks the suspension for the pendulum. Comparable clocks have a wrought-iron support mounted longitudinally on the movement. It may have been attached to the still existing wing nut and was in any case not retrofitted until 1850.

Due to the renovation work on the church, unfortunately some parts of the pendulum have been lost. However, thanks to the personal commitment of Mr. Uwe Bahr the pendulum was hung in the church. This was not that easy because of its length. After our visit, I have sketched the pendulum in its original composition, which originally was between the lens and the regulator nut. Considering the teeth number of the clockwork one can deduce the correct pendulum length of 6.21m.

Left: pendulum lens | Middle and Right: Drawing of the watch mechanics

The Zachariä-Clock

The mechanical watch, which has been installed in the tower in 1936, is still operating and shows the time on the blue outer dial, which was manufactured in 1986. The clockwork was housed in a separate wooden shack and visible through a window from the entrance hall until the church was renovated. Unfortunately, during the renovation in 2008 the beautiful housing with the window was “discarded”.

It is a tower clockwork by Zachariä from Leipzig. Zachariä had a special connection to Glashütte, as he studied at the local watchmaking school. The hands are driven by a short vertical shaft and an angular gearbox, on the pointer shaft sits a fairly large counterweight to balance the hand wave. The pointer movement is housed in a box mounted on an iron beam.

Remarkable are similarities with the design of Lange’s house clock. This is certainly due to the fact that Zachariä has also overhauled Lange’s house clock and taken over practical designs for his works. Identical is the type of pointer position, which is done via a rectangular toothed sixty-toothed wheel by lifting a lock in minute steps. The wheel sits directly on the roller shaft and is coupled to the roller via a planetary gearbox.

Mr. Rahm said the watch was serviced and repaired by Mr. Vogler from Dresden. In the past, horizontally there was a forward-facing control dial at the pointer shaft (the small bevel gear is still present) and a control disc for winding and ringing with mercury switches. Unfortunately, this part has been removed. Mr. Rahm said, now one have to communicate by mobile phone when adjusting the pointer position and be very careful not mix up the direction of rotation.

Left: Tower of the St. Wolfgang church | Middle: Blue dial | Right: Window to the outer dial
Left: Roller shaft | Right: Tripartite clock work
Left: Quarter-stroke | Middle: Looking plate for hour strikes | Right: Wire rod to the bell

The clock work is tripartite with arcade-shaped, green coated cast plates. The levers are partly cast and painted black, it is certainly the original color.

At the front, the quarter-stroke is positioned. The levers slide with pins on the cam discs of the wheels. This striking has a special feature, it does not have a separate lock disc. The roller wheel has short and long lifting nails and rotates once an hour. The lock lever has a screwed-on shoe, which then sits on a long lifting nail when the blow is to be repeated. The lifting nails thus have the same function as a lock disc. Closer to the center, the roller wheel carries a single pin, which starts the hour-striking mechanism after completing the quarter-hour striking via a long lever.

The hour striking mechanism directed to the outer dial is a locking plate striking mechanism with an external locking plate. The wire rods and the angle levers to the hammers have probably been overhauled only before the shorter, the levers are painted grey. In front of the wall of the front room there is a wooden shaft on the ceiling, which transmits the rotational movement. The hammers are stored in the bell chair and hit the bells from the outside.

Left: Crank | Middle: Functioning of the synchronization | Right: Synchronous motor

In the middle is the movement, a common graham movement without intermediate lift. That is why the amplitude of the pendulum is very large. The technology is well-known for Mr. Rahm and it is quite likely that he is looking after it himself. Fortunately, everything is well lubricated (with tower clocks too much is better than too little). The pendulum spring was broken once and was replaced by a trimmed saw blade, which has worked to date.

The three individual works are connected lengthways by a shaft with three screws. A motor flanged on with a spring clutch rotates all three rollers via this shaft and takes care of winding the clock. The rollers have externally toothed planetary gears, in order to keep the power during the winding process. A frame of thin angle irons attached under the carrying structure by Mr. Vogler ensures that it is switched off when the first weight lifts this frame. Just in case, a hand crank still lays on the window sill of the housing. There are several additional requirements for the weights. These are used to increase the driving force during winter, when oils and fats have become tough due to the cold. Some are lying on the ground; others were misused as cable holders in the gallery.

A modern night shutdown for striking has also been retrofitted. The magnet for this sits under the walking frame on the floor, blocking the cable guide to the hammers. It is controlled by a modern time switch mounted on the wall of the housing, which does not want to fit into the picture at all.

A special feature of the clock is the built-in synchronization of the pendulum by the frequency of the power grid, for which Zachariä owned a patent. It is a synchronous motor built into a round housing, which rotates a disc at exactly the speed that corresponds to the oscillation period of the pendulum. Like a connecting rod, a push rod is attached eccentrically to the disc, which has an iron angle at the end. The pendulum has a pin on which the rod with the angle can be placed. If the pendulum swings synchronously with the speed of the disc, the pin remains in the corner of the angle. If the pendulum deviates, the angle on the pin begins to rise. The slight lateral pressure is sufficient to gently synchronize the pendulum with the speed of the disc. The clock is running as accurate as the mains frequency of 50 Hz is maintained. That probably didn’t work in GDR times. Nowadays the mains frequency is very constant, but unfortunately the device is not operating anymore.

Renovation of the clock movement in 2020

The renovation of the forecourt in front of the church was planned for September 2020, a memorial for Walter Lange was to be erected. He really deserves it, without his commitment the upswing in watchmaking in Glashütte would certainly have been less successful. But thinking of the Glashütte watches, one shouldn’t forget the clocks within in the church, as they are closely linked to the history of Glashütte watchmaking. This is the reason why we – Uhrenmanufaktur Lang & Heyne – decided to sponsor the overhaul of the Zachariä movement. After all, the watches from Glashütte are also examples for the construction, design and quality standards of the wristwatches from “Lang & Heyne”. Since the Dresden company “Uhrentechnik Vogler & Hippe GbR” already knew the clock, we commissioned them to overhaul the clockwork. On September 23rd 2019 the time had come, the colleagues in the tower clock workshop dismantled the three parts of the movement and transported everything to their workshop in Dresden.

Demontage of the movement by Uhrentechnik Vogler & Hippe GbR
Reworking of the synchronous motor
Pendulum suspense, left before and right after reworking

There the three parts of the movement were completely dismantled, cleaned and repainted. Certainly some pivot bolts of the gears had to be ground as well as pivots replaced. The pallets of the Graham escapement are also given a new polish during such overhauls. The synchronous motor for the pendulum synchronization was also overhauled and the now lost rod with the bracket was replaced.

In the meantime, we cleaned the clock chamber thoroughly, rebuilding the former housing of the clockwork was not possible unfortunately. The overhaul of the pointer mechanism and dial would have blown our budget, but maybe one of the Glashütte companies will step in here? After installation, the movement will hopefully run again for many years.

Usually it can be viewed upon request. Because of the corona pandemic “Glashütte Clock Days” of 2020 and the city festival, which always takes place at the end of May, had to be canceled. During these days the church offers guided tours, where this clockwork is shown and explained. The monument to Walter Lange presents just as we remembrance him. Grounded and life-size extending his hand to us. The place looks clean and tidy, almost too geometric compared to the church which is made of natural stone. Before the renovation, there was a common beech, a boulder lay under this tree with a plaque commemorating the flood. In front of it was a bench, a very cozy place with a view to the city. It seems that the architects did not take these elements into the concept and thus removed the stone not considering the background of its installation. Let’s hope that the clocks will be spared such a fate in the future.

Pendulum suspense, left before and right after reworking

The chimes of the church

In autumn 2008, parts of the roof structure and the roof of the church were renovated. The iron bells were replaced by new bronze ones.

Long before that, the bells were operated electrically. The controls for this were very interesting, and we had the opportunity to experience the technology in operation again beforehand. Unfortunately, today strict regulations prohibit the continued operation of such systems. Since the technology is almost as interesting as a tower clock, I would like to briefly introduce it here. So let’s go back to spring 2008:

Mr. Rahm said that it is urgently necessary to renew the bell cage and the sheet metal planking of the spire and that this will happen soon. The bells are moved electrically; this device was installed with the motors in 1928. A similar facility can be found at the Frauenkirche in Meißen. A link chain rests on a large steel hoop on the bell suspension, and a three-phase motor is located below, driving the chain.
To ring the bell, the rotation direction of the motor must reverse in time with the bells swing. There is a smart solution for this. Facing enquiring gazes, Mr. Rahm pulled out a screwdriver and opened one of the switches that was hanging on the wall in the anteroom. At the back of these elongated iron boxes one could see a horizontal lever with a counterweight, which is connected to the bell by wire and rollers. Mr. Rahm now switched on the bell.

Despite this demonstration, we were unable to clarify how the switches work in detail. There is a pivoted flywheel gear tilting the switch below. Behind, is a spring-loaded lever with a knee lever tongue similar to that of the “Hippsch” clocks. This probably enables the switching to suddenly take place. The swinging bell moves the external lever with the counterweight via a wire, which pivots the gear attached to it. As a result, the flywheel rotates, which then moves the gearbox with the changeover device when the bell stops at the reversal point and swings back. The motor is then switched over by the movement of the bell and the flywheel gear in opposite directions.
The power unit was delivered by the Herford electricity works Bokelmann & Kuhlo.
The company was founded in 1896 by Eduard Bokelmann. When Eduard Kuhlo joined in 1896, the company began manufacturing electromechanical bell drives. The direct electromechanical drive was invented in 1903. In 1910, the most modern chimes of the time were installed in the Cologne Cathedral, which could control three bells simultaneous. The bell machines for St. Peter’s Basilica in Rome were also built in Herford in 1931. They all date from the same period as the Glashütte machines.

In the wooden ceiling of the belfry there are still pierced square timbers with a mushroom-shaped head. These are the rope lead-through in case the bell has to be rung by hand.
The times of the bell have long been controlled electromechanically. This was done from the tower clock via a steering wheel that operated a mercury switch. Mr. Rahm was able to keep this device.

Author: Development Director Jens Schneider
Passionate watchmaker, has been following the development of the Protestant town church St. Wolfgang in Glashütte for many years.

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