Expert: Martin Meyer - 12/5/2008

Question
QUESTION: I read your responses to the question of replacing pendulums. I have a Ridgeway Model 205, serial 81878 from 1979. (EW movement). I purchased it from the original owner. It is a beautiful case, but the pendulum is very plain...wood with a 7" plain brass disc. In reading your response it seems it might be possible to replace this with a lyre type. If so can you point me to someone who can spec out what I need? (I assume besides the same length pendulum I'll need additional weight in the center weight and possibly a new suspension spring)

Thank you,

Gary

ANSWER: Hi Gary,

I can only answer your question generally without having the make and model numbers of the movement, as stamped on the movement's back plate.

If you have a Hermle movement the conversion will be much easier. Hermle lyre pendulums are available from clock supply houses in all Hermle lengths. If your movement is another manufacture, the process could be difficult. First, the top hook of the pendulum must be compatible with the pendulum leader on the clock. Changing the top hook on a lyre pendulum is difficult or impossible because the hook is either riveted on or is an integral part of the pendulum. Because only Hermle lyre pendulums are readily available, changing the top hook will be a consideration if you have any other make of movement.

Next, keep in mind that the disk on a lyre pendulum will probably be much wider than your original wood pendulum's disk. This can result in the pendulum hitting the sides of the clock case. You must be sure that your clock's case is wide enough to accommodate the new pendulum. This is especially an issue for "pinch waist" clocks, which have a wider top section and base, with a narrow body between.

You are correct that you will probably need to add weight to the center weight. The general rule is that for a wood stick pendulum, you have two lighter weights and one heavier weight. The heavier weight goes on the right (as you look at the clock), so the left and center weights are the same. For a lyre pendulum, you have two heavier weights and one lighter. The lighter weight goes on the left. Therefore, you will probably have to add weight to make the center weight as heavy as the right-side weight. The suspension spring is not an issue and should not have to be changed.

If you need more information on the movement in your clock, please send me a followup with all numbers and other information stamped on the back plate of the movement.

---------- FOLLOW-UP ----------

QUESTION: Here is what I found on the movement. Stamped on the back (in very small type). I think it says URGOS, Made in Germany with numbers of UW32073B and 1013700. Typed on a paper label is Model 188, Movement GW, Serial 112178.

I would be willing to replace the movement if easier. The dial is a moon phase dial.

It is not a pinched waist. Straight from top to bottom. Inside "swing" distance from side to side is 17.5" +/-r2eyp

Answer
Hi Gary,

As this is an Urgos movement, replacing the pendulum will be difficult. If you could find an Urgos pendulum for sale used, perhaps on an auction site, your job will be much easier. Your movement takes 116cm pendulum, and that is what you must replace it with. Otherwise, you would have to buy a Hermle 114cm pendulum and find a way to change the top hook to an Urgos style.

Replacing the movement with a Hermle will require changing the dial as well to a Hermle dial. There is an alternative to this which is sometimes possible; see my recent answer "Tran - Which dial can use for Urgos movement" for details on this. As your clock has a moon dial, you will have to modify the moon dial gear on the hand shaft to fit the hand shaft on the Hermle, which is a different diameter. Also, the distance from the bottom of the movement (where it sits on the seatboard) to the handshaft will be different, so you will have to adjust for this as well. That issue is also discussed in the above answer. Changing to a different make of movement often presents unexpected compatibility problems, and can sometimes get rather difficult.

Your Urgos movement is a 1)small plate movement, 2)Triple chime, 3)chain drive, 4)3600 beats-per-hour (116cm). The closest matching Hermle movement would be the 1151-050/114cm movement.

You should check with the movement distributor to find out the width of swing, but the dimensions you mention sound plenty wide (just my guess!).

The weights specs for the 32073 with Lyre are: Left-4.5lb, Center-7.5lb, Right-7.5lb. For the Hermle 1151-050 with lyre 165mm diameter or less they are: L-4.7lb, C-4.7lb, R-7.3lb. With lyre larger than 165mm or greater or with second hand they are: L-4.7lb, C-7.3lb, R-7.3lb.  http://www.clockmasteronline.com