Kienzle time and strike movement servicing

I have just one other Kienzle clock in my collection and it is a rather unusual one, the World Time desk clock from the 1940s. I do not come across Kienzle clocks very often. They are no lessor quality than most German clocks, I just don’t see many around this region.

Kienzle World Time clock
Kienzle World Time clock

The latest is a German styled round top box clock. It was a an auction buy. I knew it was German at the time but did not know the maker. After a little research I discovered that it is made by Kienzle Uhren.

Kienzle Uhren GmbH is a well-respected German clock company that has a long history.

The company was founded in Schwenningen in southern Germany, in the Black Forest, by Johannes Schlenker, in 1822. In 1883, Jakob Kienzle became part of the family by marriage, and took control of the company, becoming its sole owner in 1897.

Jacob revolutionized production by mass-producing individual components and then assembling them. This modern manufacturing approach led to a massive expansion, and by 1939, Kienzle had over 3,500 employees and was making about 5 million wall-clocks and table clocks per year.

The company continued on through the years, changing hands a few times and gradually shifted production to wristwatches. It continues in business to this day as a watch maker.

The movement

In many respects it is a typical well-engineered German movement from the 1930s. The movement is compact in design and anyone who has worked on German movements will feel right at home. It has a 43 cm pendulum length and runs at 104 beats per minute as per the stamping on the back plate.

Kienzle movement, back showing pendulum leader and strike hammers
Front plate showing rack and snail mechanism

Unfortunately, the spring barrels cannot be removed separately, the movement must be completely taken apart to replace the mainsprings if they break.

The 4 hammer strike assembly can be taken apart separately. One advantage is that once the plates are back together the strike paddle can be easily positioned on the star wheel. The strike has a repeater function which is handy.

With top plate off and showing the placement of the wheels

All parts are hand-cleaned before putting them in the ultrasonic cleaner. Taking excess oil and grime off the movement prior to cleaning ensures a longer life for the cleaning solution. When the solution gets dirty enough I discard it.

The movement has a combination of leaf and lantern pinions, leaf pinions on the second wheels and lantern pinions up both trains. I expect the ultrasonic will do a great job cleaning the lantern pinions.

Taking the mainsprings out of their barrels

The mainsprings must be taken out to be cleaned and the barrels cleaned in the ultrasonic. The springs are quite powerful and mainspring troubles account for many problems with German clocks.

When the mainspring breaks movement damage can result. Teeth are torn form the barrel and the first leaf/lantern pinion is destroyed or the second arbor is bent. I have had movements go both ways from severe damage to simply a broken mainspring (which is easily replaced).

Cleaning of springs and barrels is therefore essential not only to ensure they are free from old oil and dirt but to inspect them for cracks, breaks, and tears. These mainsprings appear to be in very good condition.

Parts are sorted into containers

I typically preheat the Polychem Deox 007 solution and run parts for 20 to 30 minutes in the ultrasonic, switching off the heat midway through the cycle. I dry all the parts by hand and for the lantern pinions and some parts that seem to hide water, I use a hairdryer to ensure that everything is free of any potential rust build-up.

The mainsprings, which are cleaned of old oil are done separately in the ultrasonic cleaner.

All parts except mainsprings are placed in the ultrasonic cleaner

The next step is putting the re-oiled mainsprings back into their barrels and for that a spring winder is a must. Polishing the pivots come after that.

Olie Baker spring winder. Cleaning the strike side mainspring
Olie Baker spring winder. Cleaning the strike side mainspring

Bushing work

This movement might have been cleaned at one point in its life based on pivot scratches on the inside of the plates and worn screws on the back cock but it has never been bushed. When I tested the wheels in the movement I found the time side ran relatively freely while the strike side seemed stiff and sluggish. So, the movement is worn but the wear would be no more than typical for its age.

Following my first assessment I have determined that the movement requires as many as 10 bushings, 6 on the backplate and 4 on the front or, 5 on the strike side, and 5 on the time side. As expected there is more wear lower in the trains.

On the front plate are:

  • The second wheel time side, third and fourth wheel on the time side and the verge.

On the rear plate are:

  • Second wheel on the time side, second and third wheel on the strike side, third and fourth wheel on the strike side and the verge.

I always like to start with the most difficult, the pivot hole on the back cock which supports the suspension spring, crutch and pendulum.

In total 12 bushings were required, including the escape wheel. The escape wheel was pretty sloppy both front and back, and better to do those while the movement is apart. 12 is probably the most I have installed in a German clock in quite a long time.

Reassembly and testing

I generally perform a power test prior to the final assembly of the verge, rack and snail, and all outside pieces. It is a good check against my bushing work and if anything is tight or stiff I can address it without taking everything apart. Everything looked good at that point.

Both trains are moving and being tested before the other parts go on
Both trains are moving and being tested before the other parts go on

However, with verge installed, pendulum leader, crutch and pendulum, the movement consistently stopped after a few minutes. I took it apart and discovered that the 4th wheel on the time side was moving stiffly. As that wheel had a new bushing installed all it took was reaming out the pivot hole to free it up. Now the movement is running well.

Testing the Kienzle movement on a makeshift test stand
Testing the Kienzle movement on a makeshift test stand, beat amplifier is attached

Onward to the strike side and attaching the levers, snail and rack. The levers, rack and snail and gears are attached and finally the strike hammers are installed. The strike hammer posts must be bolted in from the inside of the back plate, something to remember when reassembling the movement.

When I got the clock only one strike hammer functioned but with all hammers repositioned all 4 strike hammers are doing their job and producing a melodic bim-bam strike.

The case does not require much attention other than a cleaning with soap and water.

There is absolutely nothing on the movement, gong block or case that tells me who the maker is though I now know it is definitely a Kienzle.