Clock pendulum components description
Altogether, this is a description of the clock pendulum parts and components. Please use this as a glossary of the parts to a clock pendulum assembly. Knowing the correct terms for the various pendulum parts is helpful when locating replacements. We are pretty adept at deciphering descriptions of parts however knowing the name is always something we welcome.
The clock pendulum
Clock pendulum leader
Naturally, pendulum leaders vary depending on the manufacturer of the clock movement and they can also vary in length as well as style. Sometimes there can be more than one type of leader for the same movement.
Suspension spring description
The clock pendulum suspension spring is the short spring steel part on the very top of the pendulum assembly. Its purpose is to suspend the leader and pendulum in the air. Generally speaking, its steel spring like strips flex to let the pendulum swing back and forth with ease and momentum.
Clock Pendulum Components Complete
Put the complete pendulum assembly on the clock and it is ready to go. The next step is to put the clock in beat and run the clock to see how the time keeping is.
Replacing Lost Pendulum Parts
By and large, replacing a lost pendulum part from its assembly is a process. It is more in depth than just matching up the broken pendulum part. Certainly, narrowing it down requires a different method than just observation. The following text will guide you through that process.
The lost pendulum
First, identify the movement manufacturer. This is the beginning step to identify a lost clock pendulum. This is done by getting the movement numbers off of the back plate of the movement itself. That is to say, it will not be in the manual that came with the clock. Moreover it will also not be on any stickers or the clock case.
Lost pendulum leader
If the leader is missing, identify who made the movement. Use the above information to correctly identify the movement so it is possible to replace the pendulum part. The leader possibilities are narrowed down considerably upon knowing who made the movement. This makes things much easier when replacing lost pendulum parts. After knowing the manufacturer, match the information to a leader shown on this page.
In the final analysis, visually inspect the pendulum hook style, the crutch on the back of the movement, and the suspension hook. Finally, compare the components of the clock to the options in that manufacturer category to figure out the best one. Replacing lost pendulum part can be tricky however with these descriptions the task should be less daunting.
The lost suspension spring
First know that style A is the very most common suspension spring style in existence. Check the top of the pendulum leader and if there is a double hook on the end it will be style A required for the clock.
Generally speaking, style A3 is used for large grandfather units, A2 for grandmother and wall clocks, and A1 for mantle clocks. Suspension spring are one of the easier parts to ascertain when replacing lost pendulum parts.
The mechanical clock pendulum length
A pendulum clock without a pendulum is a shame for sure. Hence, getting the mechanical clock pendulum length correct does take some diving into the clock world.
If there is no idea what pendulum it would take, this is a basic guide. Of course, this is a basic guide to narrow it down to the best pendulum for the clock. This will cover most situations, without special equipment to figure out the length.
The movement CM or PL stamp
On the back plate of the clock movement usually, there are some numbers and or letters for identification. Likewise, there may be an indication of how long the pendulum should be in the mix of these numbers.
It may say CM or PL and this stands for centimeter or pendulum length. Subsequently, this would be the length where it should keep approximate time. Generally, this is measured in a few different ways usually dependent on country of origin.
Mechanical Clock Pendulum Length for German made movements
Most mechanical German made clock movements are easy to figure out the pendulum length. In essence, the numbers will let us know or the stamp will clearly state the CM or PL number. If it is German, keep in mind the CM length is not the actual pendulum length.
Altogether, German units measure this length from the top of the clock movement, and this includes the three components of the pendulum all in one length, in centimeters.
This length will include the pendulum itself, the leader that it hooks to, and the suspension spring on the top that the leader hooks on to, all in one CM measurement. To clarify, CM stands for centimeter and PL stands for pendulum length.
If no stamp try to convert
With no pendulum length stamped into the movement some added steps are involved. The numbers on the back plate will cross reference to the pendulum length required. The first step is to identify the manufacturer of the clock movement by using the movement numbers.
The movement numbers indicate who actually manufactured the movement. Various clock retailers may have have their name stamped onto it, but the numbers are always true to the manufacturer.
Converting numbers to CM length
Moreover, some movements do not have an indication of the pendulum length on the back plate. The unit will have a number that would need to be found on this website first to find out what the correct CM length is for it.
Converted number example
Go to the identification page to look at the movement number examples. In this example, we see that it is a Urgos. Now it is possible to go to the Urgos page and find the number to see what the pendulum length is.
In this example, the pendulum length would be 80cm, representing the full length with the size of the bob factored in.
German grandfather movements
Almost all grandfather clock movements are going to be German if made after 1950. The first thing we need to do is get the numbers off of the back plate of the movement. This is the only way, and we can't cheat by looking at the paperwork or clock case.
It has to come right off the back of the clockworks. The manual and the sticker on the case is of no use to get the pendulum.
The American mechanical clock movement manufacturers referred to the pendulum length as a "drop". The drop is the length of the pendulum from the hand shaft all the way down to the bottom of the pendulum rating nut threads.
It is a different way of measuring the pendulum length then the German made way. Both ways are based on the smallest bob diameter bob. If the bob is larger or heavier, the length would be longer than what is stamped.
These types of clocks are usually antiques, or of Asian origin, and information such as pendulum length is simply not available. Sometimes it takes a good guess on where the manufacturer intended to have the bob sit.To do it this way, it is only needed a pendulum with a stick that is way too long to begin with.
Chop it, try it, chop it, try it. Each time slow, cut an inch and half off of the sticks length and hang it back on. It will only take a couple of times, and if starting way too long it can always go shorter.
Clock makers method for Mechanical Clock Pendulum Lengths
There is another way, its called setting the beat rate. This is a more involved way and usually just done by clock makers. It involves a beat detecting device that counts out the beats per hour, or the beats per minute. To do this, first figure out what the beat rate is supposed to be for that particular movement.
Then keep adjusting the pendulum length until it keeps time. There are cell phone apps out there these days that will tell the beat rate and the cell phone will listen and say if the clock will keep time with that pendulum. Go longer or shorter until the phone says the beat rate is set.
Contacting us for help with Mechanical Clock Pendulum Lengths
Please email the movement numbers from the back plate, and explain what part is needed. The email address to send this information is [email protected] Pictures are welcomed but not required. If emailing pictures please include the back side of the clock movement where the markings are.
Timing a mechanical pendulum clock
Fine timing the clock
If the clock is timing slow, raise the pendulum bob by turning the nut at the bottom of the bob. If the clock is fast, do the same but lower the clock's pendulum bob instead. One full turn is somewhere around 1-2 minutes a day faster or slower.
If there is no more adjustmentIf the bob is all the way up and its still too slow or fast, shorten either the pendulum or the leader it hangs on to correct.
It is possible to shorten or lengthen the pendulum leader to put the clock in time range with some solder if needed. 1 3/4 inches is a good measurement to make one of these longer or shorter as needed, as this is the length of the threads at the bottom of the bob.
So it will give a full timing adjustment range all over again and can go up or down as needed.
German pendulum length CM stamp
The pendulum length is overall and not just the pendulum itself. These German units measure there pendulum lengths from the top of the movement and all the way down. This will include the suspension spring, the leader and also the pendulum itself.
Used to keep time, now does not
If the clock kept time in the past but now does not, it means a worn gear. The escape wheel is worn and it is advancing more than one tooth at a time.
The escape wheel alone would be hard to find, and hard to replace both. The entire movement would be disassembled to replace this worn escape wheel if there is another one found that will work.
The price would be about the same for a complete overhaul or a brand new one. First see if the clock movement is in production and available new. We do this by getting the numbers off of the back plate of the movement itself, right off of the brass. Please email and we will check the availability and quote for the new one.
Mechanical Pendulum Clock Timing Issues - Conclusion
Fine timing of the clock is easy as seen. If the clock kept time in the past and now too fast, its time for a new movement and has nothing to do with the pendulum. A worn escape wheel is most likely the cause and a new unit would be less cost then a repair.
Clock Pendulum Suspension-Spring Information
The following is a discussion on clock pendulum suspension-spring information. Naturally, suspension springs do not have to be exact in length. If the clock runs slow, simply raise the pendulum bob with the rating nut at the bottom.
Most common springs
If the old suspension spring looks similar to this one then it is right. As a general rule of thumb, small mantle clocks take suspension A1, wall clocks and small grandmother units will take suspension A2.
This size can also be seen on Grandmother clocks with larger bob diameters. Use the larger A3 with large bob diameters so the bob will not wobble front to back.
Not as common
Clock Pendulum Leaders
If the leader does not match up to any of the ones listed, please email us. A picture is always helpful. Look to see if the leader needs a double hook or a hole top in order for it to mount to the suspension spring. Similarly, check the other end and notice that configuration as well.
What is the required mount style for the pendulum to hang on the clock? In the middle section, what one will engage with the swinging crutch on the back of the movement? These are all important factors to consider when replacing the leader.
The length of the leader
If the leader is missing, however, there are some more steps to figure out what the leader length should be. Not all leaders have variable lengths and the ones that do are for Hermle and Kieninger clock movements only.
Hermle leader lengths
A Hermle floor or wall clock will always take leader D or G. leader E is for a low bridge to a high bridge conversion on a Hermle grandmother clock. Therefore, the elimination of this from the list of choices is viable if a conversion is not being done.
Leader F for Hermle mantle
This will ensure that the correct leader length is chosen. First, use the CM number off of the back of the movement. This CM length is the pendulum length from the top of the movement all the way down to the bottom of the pendulum.
It is not the length of the pendulum itself. Often times this measurement can be confusing. It is important to measure this correctly. Failure to do so will result in the clock not keeping proper time.
Second step, is to take this CM length and divide it by 2.54 to get the inch equivalent. Then subtract the length of the pendulum and the suspension spring length from this measurement. The measurement that is left is the length needed for leader F.
There are 1 1/2 inches of thread at the bottom of the pendulum for fine adjustment. Because there is so much room for adjustment, this measurement does not have to be exact. If there wasn't any extra length then it would need to be more precise. However this is not the case so close is good enough.
If the leader is the wrong length
The timing of a clock is determined by the length of the pendulum and the weight of the pendulum bob. This can get a bit confusing for some people. The overall pendulum length is stamped on the back plate of the clock movement with a CM number.
Subsequently, a wider pendulum bob will require a longer pendulum. Again, this can get a bit tricky. Please feel free to send an email with any questions. We will be glad to help.
If all else fails, a different leader length may need to be bought. Before shortening a pendulum it would be best to contact us to see if this is the best option. Cutting the pendulum is the last resort.
As seen, this is not a cut and dry procedure. There are many factors that play into getting the correct combination so the clock will keep correct time. The correct leader is just one part of the whole process.
Measuring is also important. No matter what situation it is we can surely find a solution. Don't ever hesitate to reach out and ask a question. Pictures are always good to send so we can see what exists now. Email is always the fastest way to contact us.
Clock Pendulum Top Hooks
What they fit
It matters only that the pendulum can hang into the air onto the leader and be stable. Antique clock pendulums can use any one of these top hooks if it will do the job.
How to install
The top hook installation is by friction only. Bend the tabs over and use a punch and a hammer to secure it to the wood stick. Another way is to drill starter holes into the top hook and secure with screws or nails.
Hermle Custom Pendulum LeaderSpecial Hermle custom pendulum leader made 4 3/8 inch for a low bridge to high bridge Hermle conversion. High bridge means the suspension spring post is on an A frame about 1 1/4 inches above the movement.
A low bridge would have the suspension post even with the top of the movement. When going from LB to HB this shorter leader is so the clock will keep proper time.