Mason Sullivan Clock Movement

Mason and SullivanM+S movement identificationOrdering the clock movementWhy get a new clock movement?What happened to the old unit?

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Mason-Sullivan clock movement Identification

If the movement says Mason and Sullivan it does not mean it has a Mason-Sullivan movement number. Often the use of their own numbering system was on the clock movements.

This was done in the later years of the Mason and Sullivan company history. Generally speaking, it is best to match up the ID numbers on the clock movement identification chart if not already done.

If the clock movement number ends with an X, then the Mason and Sullivan chart page is the right place to be. If the number does not end with an X, please refer back to the clock movement identification chart.

Why convert the number

For the most part, the Mason and Sullivan number system is not helpful to determine what the movement is. After the conversion everything will be known about the movement and who made it.

In the long run, this will allow for the purchase of parts or a replacement movement precise and accurate. Moreover, the conversion number will tell us the movement plate size, hand shaft length, hammer location and more.

How the new one comes

The new movement ships the same or next business day already with fresh oil and ready for installation. If it is weight driven it will come with chains or cables.

If the movement is a pendulum version it will come with the leader and suspension spring.


Clockworks provides the instructions for installation and also support for the clock movement. This family has a combination of over 100 years as clock makers.

Questions and problems are taken care of even after the manufacturer says it's out of warranty. Basically if needing help just ask. There are not many clock makers around anymore. So you not only get a response but it will be the correct answer and what makes the most financial sense. The manufacturer warranty is three years on a new clock movement.


Identification of the Mason and Sullivan clock movement is the first step. It will grant the customer the ability to shop for a movement or components. Without the identification process everything is in the dark, so to speak.

It is like a secret code that you need to crack open. It can get confusing but we are here to help. When contacting us, the movement number will be the first thing we ask for. If having trouble locating it, email a picture along with the question.

This way we can see what you have in the clock. Once the movement has the proper identification, it is a good idea to write it down and keep it inside the clock case for future reference. That way this whole process does not need to take place again.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

Ordering a Mason-Sullivan Clock Movement

Ordering a Mason-Sullivan Clock Movement is easy but you may need to convert it to the real number. If an X is at the end of the number that is on the back plate, yoju will need to use the conversion chart.

If the number has no X at the end, you will need to determine who made the clock movement for M/S. This is very easy with the clock movement identification chart. Pay particular attention to Hermle units as that is what they use the most.

The number ends with an X

If there is indeed an X at the end of the number on the clock movement, you need to use the Mason and Sullivan chart. Convert that number to the real manufacturer's number on the chart and write it down. It is best to also put that conversion number inside of the clock case for future reference for ordering any components. When searching for parts or talking about the clock, use the conversion number and not the original that ends with the X.

Why the conversion number helps

The new number will help find keys, pendulums chains, or any other part. The old number makes us blind to all this.

Whereas the conversion number turns on the lights. It will enable the user to talk about the clock and replace the movement. Everything about the movement and its components will be known and help with any future questions.


Use the Mason and Sullivan conversion chart to get the real movement number and write that number down. Click the number that is by your old number on the chart. It will go to the page where the clock movement is available for purchase. Many movements come in multiple CM lengths and this only has to match both the new and old.

Matching CM lengths

You do not need to measure the pendulum at all during this. The reason is because the numbers and the CM length tell us everything. The CM length stamped on the movement is not the actual pendulum length.

The discussion on how to measure a pendulum is in a different section, but this is not a requirement for replacing. All you need to do is to select the same CM length as the conversion number dictates and it will be the correct unit.

The new movement will run the same pendulum and also every other component that you currently have in the clock. If it is a pendulum unit, you will need to use the drop down menu and select the CM from the list when ordering.

How the new one comes

The movement that will be sent to you will have a different number but it will be the same movement. The new movement comes with the chains or cables and pulleys if it is weight driven.

Ordering a Mason and Sullivan is really not Ordering a Mason and Sullivan after all but you will get the same unit brand new.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

Replacing a Mason-Sullivan Clock Movement

Replacing a Mason-Sullivan Clock Movement only requires the most basic tools. A pair of needle nose pliers and both styles of screw drivers is usually all that you need for the swap out.

The new clock movement will be the same movement you have now but brand new. So everything will fit the same as it did. Having a Mason and Sullivan clock movement puts the movement 40 years old. The company went out of business this long ago so it is time to swap it out. Because the old one was able to work night and day for 40 years without too much complaint, the new one will do the same.

The disguise

The Mason and Sullivan company from MA USA built and sold countless clock movements and clock kits.

So many they were able to convince the makers of these units to have their name on a stamp right on the movements. Not long after that, they even had their own numbering system put in place instead of the makers numbering system.

The Availability

Although they are now out of business we can still replace the clock movement. The movements were not their own anyway and the movement producers are still in business for the most part.

in other words, the German manufacturers are making the same movements as they did 40 years ago. A new movement will last longer than even the very best overhaul by the best clock maker.

Also, the movement would be half the price of even a cleaning on the old unit and be brand new instead.

The Identification

The first step is to ignore any names on the clock movement and only pay attention to the numbers. Match the numbers on the ID page to see who made it. It may or may not have a M/S number on the back plate itself on the low right.

If it is a M/S numbering system an X will follow at the end of the number and go straight to the conversion chart. It will say something like 3325X or similar. This is if the clock movement has the Mason Sullivan number system only.

As in the previous explanation, the exclusive M/S numbers were only in the later years. Prior to this it would have the M/S name and the real makers numbering system. If do not have an X in the number it is most likely a Hermle movement so go to that web page to match it up.


The clock movement is most likely a Hermle movement in disguise. The new unit can ship the same business day if we receive the order early enough, comes with oil already.

It will have its chains or cables if it's a floor clock movement, comes with instructions and support to install the unit.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

Mechanical Clock Movement Wear

Mechanical clock movement wears out after years go by because the oil turns solid. With age, the mechanical clock movement's oil solidifies and becomes black and sticky.

By the time 20 or 30 years go by, the oil has solidified and is creating wear on the brass plates of the movement. So, when this happens, the clock movement will not run correctly.

This is when the movement will need a cleaning at least, or be replaced. Of course, a brand new movement is always the best option.

What wear and where

Look at the old clock movement, and see holes in the brass plates where there are small pivot arbors sticking into these holes. These pivots are what the gears of the clock ride upon and as the pivots spin in the solidified oil, this makes the holes oblong instead of round.

With the pivot holes oblong, the holes are pinching the pivots and creating resistance in the gear train. With the solidified oil and the pinched pivots, the clock will eventually stop working or chiming.

Invisible clock movement wear

This wear takes place in the holes that are in the brass plates and is hard to identify sometimes. These holes in the brass plates become oblong instead of round and this pinches the pivot arbor going into it. Between this, and the solid oil, the clock ceases to function.

To have this repaired is an expensive and long process. To have a mechanical movement serviced can cost two times as much or even three times the amount of the new one.

However, once the movement starts having problems due to the oblong pivot holes, something will need to be done. The clock will never stay running otherwise.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

Mason and Sullivan Clock Movements

Movement #Chime TypeDriven byCM lengthHandshaftPicture
3200X = HT116Triple ChimeCable Driven116cm56mmPic
3201X = HT116Triple ChimeCable Driven116cm56mmPic
3206X = KSU78Triple ChimeCable Driven116cm47mmPic
3210X = KSU78Triple ChimeCable Driven116cm47mmPic
3211X = KSU78Triple ChimeCable Driven116cm47mmPic
3213X = KSU78Triple ChimeCable Driven116cm47mmPic
3223X = KSU78Triple ChimeCable Driven116cm47mmPic
3227X = KSU78Triple ChimeCable Driven116cm47mmPic
3230X = 461-053 114cmWestminsterChain Driven114cm53.2mm
3231X = 1161-053 114cmTriple ChimeChain Driven114cm53.2mmPic
3232X = 1161-853 114cmTriple ChimeCable Driven114cm47mmPic
3260X = 451-050 94cmWestminsterChain Driven94cm33.2mmPic
3261X = 1161-853 114cmTriple ChimeCable Driven114cm53.2mmPic
3262X = 1151-050 94cmTriple ChimeChain Driven94cm33.2mmPic
3266X = 351-050 94cmWestminsterSpring Driven94cm33.2mmPic
3268X = 241-040 94cm(N/A)Gong StrikeChain Driven94cm33.2mmPic
3270X = 451-050 94cmWestminsterChain Driven114cm33.2mmPic
3281X = KSU80Triple ChimeCable Driven93cm47mmPic
3286X = KSU80Triple ChimeCable Driven93cm47mmPic
3300X = 141-030K 66cmBim BamSpring Driven66cm33.2mmPic
3301X = 141-030K 66cmBim BamSpring Driven66cm33.2mmPic
3304X = 141-040 66cmGong StrikeSpring Driven66cm33.2mmPic
3314X = RWS13WestminsterCable + Spring65cm32mmPic
3315X = RWS13WestminsterCable + Spring65cm32mmPic
3318X = RWU03(N/A)Triple ChimeSpring Driven15cm32mm
3319X = RWS13WestminsterCable + Spring65cm32mmPic
3322X = 1051-030 43cmTriple ChimeSpring Driven43cm33.2mm
3334X = 131-030 55cmBim BamSpring Driven55cm33.2mmPic
3335X = 241-840 75cmGong StrikeCable Driven75cm33.2mmPic
3337X = 351-020K 55cm(N/A)WestminsterSpring Driven55cm33.2mmPic
3341X = 141-030K 48cmBim BamSpring Driven48cm33.2mmPic
3342X = 141-040 38cmGong StrikeSpring Driven38cm33.2mmPic
3350X = 141-040 38cmGong StrikeSpring Driven38cm33.2mmPic
3352X = 141-040K 38cmGong StrikeSpring Driven38cm33.2mmPic
3354X = 351-020 38cmWestminsterSpring Driven38cm33.2mmPic
3360X = 141-040 23cmGong StrikeSpring Driven23cm33.2mmPic
3366X = 351-020 52cmWestminsterSpring Driven52cm33.2mm
3370X = 141-040K 48cmGong StrikeSpring Driven48cm33.2mmPic
3380X = 141-040 66cmGong StrikeSpring Driven66cm33.2mmPic
3390X = 141-040 29cmGong StrikeSpring Driven29cm33.2mmPic
3393X = 351-020 25cmWestminsterSpring Driven25cm33.2mmPic
3396X = 131-080 23cmBell StrikeSpring Driven23cm33.2mmPic
3397X = 132-071Ships StrikeSpring DrivenBalance33.2mmPic
3398X = 131-080 23cmBell StrikeSpring Driven23cm33.2mmPic
3600X = 350-020WestminsterSpring DrivenBalance33.2mmPic
3602X = 1050-020Triple ChimeSpring DrivenBalance33.2mmPic
3603X = 1050-020Triple ChimeSpring DrivenBalance33.2mmPic
3604X = 150-070Gong StrikeSpring DrivenBalance33.2mmPic
3605X = 350-0203201X = HT116WestminsterSpring DrivenBalance33.2mmPic