Hermle Clock Moon Gear


Hermle Clock Moon Gear

Moon gear for Hermle mechanical clock movements. This is the gear the spins the phase of the moon function on a lunar dial. Installed on the same tube as the hour hand and secured with a set screw only.

CP25: $15.00$20.00
Moon DialsMoon Dial OrderingRemoving the HandsMoon Dial InstallationMoon Dial History

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Grandfather Clock Moon Dial Ordering

Before ordering the new moon dial for the grandfather clock, this section must be read. Not all moon dials fit all clocks, each one is made for a specific clock movement. The reason is most moon dials have four feet, or posts, that stick out the back of the dial. These feet have to lock into the movement its being attached too. If the feet are in different locations, it will not lock into the movement. They must be married together so to speak. These grandfather clock moon dials are for post WW2 clocks only.

How to get the right moon dial

To get the correct moon dial for your clock, you will need the movement numbers. This will be directly off of the back plate of the movement itself. It will not be on any of the paperwork that came with the clock, or on the wood case. Movement numbers can only be found on the clockworks itself. With the movement numbers you can match up the number with the numbers posted on the moon dial description.

What has to match

  • The posts on the back of the dial need to lock into the movement. A hand shaft that is long on the movement, will require longer posts. In other words, the posts on the back of the dial make it so the hand shaft will stick out far enough to put the clock hands on.
  • If the movement is cable driven, the holes to wind the clock need to be in the right spot. This is important for when you put the key crank in. If it is aligned correctly, it will go onto the winding arbor of the movement. When it is not aligned properly, winding will be difficult or impossible.

  • Some clocks have a second hand bit which also has to be perfectly aligned. This goes onto the small post coming off of the escape wheel. The second hand is a friction fit.

On a chain driven unit, it is possible to get any moon dial and remove the feet off the clock dial. The dial would then have to be attached to the wood case instead. Because there are no winding arbors on a chain driven unit there are no holes in the dial to line up. There is also rarely a second hand bit. So you could use any dial with no winding holes and attach it to the wood case. However, one thing to mention is that the moon phase will most likely no longer spin.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Removing Mechanical Clock Hands

Removing Mechanical Clock Hands is fast and easy to do. The following are instructions for German mechanical movements post WW2 hand removal.

German Post WW2 wall, mantle and floor models

Turn the hand nut to the left while holding the minute hand with your fingers. Some small needle nose pliers may be needed to loosen the nut first. Once the nut is loose, you can turn it with your fingers until it comes off. The minute hand will be able to wiggle straight off its square arbor and off of the clock. The hour hand is a friction fit, so just twist the hour hand back and forth and pull toward you until it comes off. If you have a second hand bit, that is only a friction also, so just grab it with your fingernails and pull toward you.

American Antique time and strike

These type of movements come in two styles. if there is a minute hand nut, the first style is the same as above. Be very careful not to lose this hand nut. They are very hard to find and replace. The second style will have a pin holding the minute hand on instead of a nut. This pin is tapered, meaning it's fat on one side and skinny on the other usually. Just grab the fat side with needle nose pliers and yank the pin out. The minute hand will fall out with a washer. Save the washer and the tapered pin for ease of reinstalling the hands.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Grandfather Clock Moon Dial Installation

A Grandfather clock moon dial installation explanation is in this section. This is written for a new movement installation in mind. However you can use it for any post WW2 German mechanical units with issues in relation to the front of the movement.

The moon gear

Install the moon gear onto the new movement prior to the dial installation. It mounts with a set screw and sits on the same tube as the hour hand. Install this onto the new unit. Of course it has to be the same as it was on the old movement. Ideally, with the same approximate distance on the hand shaft. In essence, this will allow it to run the gears behind the clock dial and therefore run the phase of the moon.

The selector switch

A selector switch is a steel arm that is about 1 to 2 inches in length with a set screw. In short, the purpose of the switch is to select the song or silence the clock. Install the selector switch on the arm which is on the right side of the movement. In other words, slide the switch over the larger arm and secure it with the set screw. It only has to be able to come through the slot at 3 o'clock position for the user to move it up or down.

Grandfather clock moon dial installation

The clock moon dial has four posts on the back that lock into the front plate of the movement. Line up the clock hand shaft to the hole in the center of the dial. Then line up the posts with the holes in the movement. There are two ways to secure the four dial posts to the clock movement. One way has locking arms on the back of the front plate of the movement that slide over the end of the dial post to lock it tight. This is if both the dial and the movement are made this way. The other way this is done is if there are holes in the ends of the dial post feet. These use a pin to secure it to the movement. A tapered pin will go through the hole in the post after it's on the movement's front plate.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Clock Moon Dial History

The phase of the moon is still popular on modern mechanical clock movements. It is interesting to know why and when this started becoming a popular feature to add to grandfather clocks.

Why it started

In the late 1600's traveling took awhile and was also hazardous at night when it was dark. The people would depend on the light of the moon to see what they are doing when they were out. The phase of the moon function was added to the floor clocks for this purpose. People could make travel plans with the moon light helping them to see.


In the 1700's clocks started to have the hump on the top of the clock dial for the moon phase. The arched dial was able to accommodate the lunar display disk. The moon was painted on the disk and the disk would rotate once a month. It was a simple and practical addition to the clock.

Alternate Animations

Some clock dials with the arch were produced with alternate animations besides the moon phase. Rocking ships and jumping deer figures among other things would rock back and forth. These animations did not have any practical functionality as the phase of the moon did. It was a simple design and was connected to the pendulum motion. If the pendulum move, the animation would rock, they were connected.

That is the history of the clock moon dial in its simplest form. Interesting how people lived and relied so heavily on there clocks back then. In the days of outhouses and traveling with horse and buggy, a clock was an important appliance.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Hermle Clock Moon Gear

Moon gear for Hermle mechanical clock movements. This is the gear the spins the phase of the moon function on a lunar dial. It is the only interaction from the movement to the dial to make the dial lunar disk to spin. Installed on the same tube as the hour hand and secured with a set screw only.

Additional information

Weight0.2 lbs

For 451 or 1151 Series, For 1161 Series, For 1171 Series

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