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The Junghans “”Arch-Top” Movement



The Junghans "Arch-top movement" (I don't know what else to call it) is unusual enough to warrant a written explanation of how it works. There is no chime correction. The movement in these pictures is from a “Chant” model bracket clock manufactured 1908-1910.





THE PARTS OF THE CHIME APPARATUS


Between the Plates



The third wheel arbor carries the Count Wheel (chime locking plate). Outside the back plate, it carries the main drive gear for the hammers. Outside the front plate it carries the Strike Finger.

The fourth wheel arbor carries the maintenance cam.

Here is a Very Important Fact: The Count Wheel (chime locking plate) can be moved on its arbor, to synchronize it with the maintenance cam. You don't need to split the plates to synchronize them.

The fifth wheel carries the warning pin/stop pin.





The Chime Lever Arbor carries the count wheel drop lever, the maintenance lever, and the chime stop hook. Outside the front plate it carries the Strike
Governing Wire.


Outside the front plate:



There is no star cam on the center shaft. Instead, there are four lifting pins on the back of the minute cannon, to operate the lifting piece, which raises the lifting lever. None of the pins is special.














The lifting lever and warning lever form a single unit, on a collar on the end of the chime lever arbor. It's not attached to the arbor. The end of the warning lever projects through the plate, forming the chime warning detent. The warning lever has a lifting pin, which raises the strike governing wire, and so raises all of the chime levers.










Below them is the strike finger, aligned with the hour sector of the count wheel. It unlocks the strike train toward the end of the hour chime.

THE PARTS OF THE STRIKE APPARATUS


Between the plates:



The third wheel is the locking wheel with the lock pin/stop pin.
The locking lever with locking detent is on the same arbor as the rack hook.
The fourth wheel is the warning wheel, with warning pin.










Outside the front plate


The strike unlocking lever is on the same arbor as the rack hook and locking lever.
The strike warning lever near the top is pivoted in the middle. It is spring loaded. On its front end is the detent, which can drop into the path of the warning pin. On its back end is a lifting pin, operated by the strike governing wire.


THE SEQUENCE OF EVENTS



At rest, the strike locking pin is resting on the detent of the locking lever.

At rest, the chime lifting lever rests on the lifting piece, the chime detent is at the bottom of its hole through the plate.
The front of the strike warning lever is raised, out of the way of its warning pin.
The count wheel drop lever is in a notch in the count wheel.
The maintenance lever is in the notch of the maintenance cam.
The pin on the warning wheel is resting against the stop hook.

When the lifting lever/warning lever goes up, the chime levers are lifted, moving the stop hook and releasing the warning pin. The maintenance lever lifts out of the cam notch; the cam moves just enough to get the notch out from under the lever.

The strike governing wire raises the strike warning lever, putting the detent in the path of the strike warning pin. It does this every quarter. It's only significant on the fourth quarter, when the strike train unlocks.

The chime warning wheel does a half rotation, with its pin resting on the detent. The train is in warning.

When the lifting piece falls off the pin, the chime detent drops out of the way of the warning pin, allowing the train to run. The chime levers remain raised, since one of them is riding on the count wheel and another is riding on the maintenance cam.

When the count wheel drop lever drops into a notch on the count wheel, the maintenance lever drops into the notch of the cam, the stop hook drops into the path of the warning wheel, and the train stops.

During the fourth quarter chime, the strike finger raises the strike unlocking lever, moving the locking lever away from the locking pin on the third wheel and allowing the train to run. It runs only until the warning pin hits the warning detent, which is held in the "down" position by the strike governing wire. The strike is now in warning.

When the chime ends, the strike governing wire drops, allowing the strike detent to spring out of the way of the warning pin. The strike train runs.

After the last rack tooth is gathered, the rack hook falls beneath the rack and the locking lever falls into the path of the locking pin. The train stops

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Current Discussion: Main discussion

  1. taliesen

    taliesen Registered User
    NAWCC Member

    May 13, 2016
    4
    1
    3
    Hello
    Excellent article.
    I understand from other postings that this is a Junghans 103EH movement (maybe) (see "Merry Christmas (And A New Junghans)")
    This is a very appropriate find for me, I have an A07 version of this movement that is giving me trouble (see "Post Your JUNGHANS Clocks Here" posting #1165 / pg 24 for pictures). The chime on the 1st quarter hour does not sound although there is a "click" to arm it. I am hoping this article will help me trouble shoot the problem.
    Richard Dillane
    Chapt. 33 Toronto
    Chapt. 98 Caloosa