There are four general categories of clock mechanisms; quartz, electro-mechanical, electric and mechanical. Mechanical clocks be they antique or vintage types are the the focus of this post.

It may surprise some to know that mechanical clocks need periodic winding

Let’s assume you came here because you have a mechanical clock. It might have been handed down to you, part of a small collection, picked up at a flea market or auction house and you managed to get it running but now it has stopped.

It may surprise some to know that mechanical clocks need periodic winding. Eight day clocks must be wound once per week, 30 hour clocks, once per day. If you have a 31 day clock it is a one month runner which means that it need only be wound once per month. 400 day clocks, sometimes called anniversary clocks, are wound once per year.

Kundo standard size 400 day clock
Kundo standard size 400 day clock, wound once per year

What does winding a clock actually mean? Most spring driven mantel clocks have winding arbours on the clock face. One key is required for all the arbours. I say this because I saw an ad recently where the seller who was advertising a time and strike mantel clock said they had “both” keys.

I recommend winding the mainspring so it does not wind any further. If it is a time and strike it will have two winding arbours; wind those till they wind no further.

Winding arbors on a Seth Thomas mantel clock (arrows)
Winding arbors on a Seth Thomas mantel clock (arrows)

There is no such thing as “over-winding” a clock. A clock that stops when you have wound it fully means that there is so much dirt, old oil and grime on the mainspring that it seizes in place. The mainspring might provide plenty of power but it needs cleaning and if it needs cleaning the entire movement should be properly serviced. A clock in good working condition should run its full cycle, a full eight days for an eight day clock, for example.

Let’s look at some the reasons why your clock has stopped.

Is it in beat? Is the clock level?

Make sure your clock is on a level surface. Listen to the tick and the tock of your clock. Try to minimize the sounds in the room you are in so that you can listen closely to it’s rhythm. It is in beat when its ticks and tocks are even….tick…tock…tick…tock…, and is out of beat when they are uneven, either, ticktock…. or tocktick…… Put another way, there must be an equal amount of time between the ticks and the tocks. When a clock is out of beat, it will either not run at all, or it will run for a short time and then stop. A clock’s beat must be regular to work properly.

There are two ways to put a clock in beat. The first is to tilt the clock sideways, one way or the other, and listen for the beat to even out. When the beat is even, prop the clock to stay tilted that way. If it is a wall clock move it till you hear a steady beat. Now it will run in beat but it will obviously not look good.

American made time and strike
American made time and strike

The second is to adjust the crutch to one side or the other, until the beat is even. The crutch is the rod that extends down from the pallets which rock back and forth on the escape wheel. The pendulum rod passes through either a loop (called a crutch loop) or a forked foot at the end of the crutch as indicated in the photo below. Incidentally, that rod needs to be in the middle of the crutch loop and can’t be tight inside the loop nor too loose. The crutch is attached to the pendulum leader which is then attached to a post with a suspension spring.

Obviously if you have a clock with a balance wheel rather than a pendulum, leveling is not critical.

Did you recently have repairs done? Unless you had a friend fix your clock most reputable clock-makers will offer a warranty, typically 6 months to a year. If your clock stops within that time frame, contact the clock-maker who may offer a few suggestions for you to try before bringing it in. If it still does not work have that person take a look at the clock.

Do you have the correct pendulum? I have bought clocks that came without a pendulum. Aside from the winding key, it seems to be the item that gets lost the most. Make sure that you buy a pendulum that is correct for your clock. One too light may mean that it not does not run at all, too heavy and the centre of gravity is lowered and the clock might run too slowly. There are clock suppliers such as Perrin or Timesavers that will have the correct pendulum for your clock.

pendulum bob with adjuster
Pendulum bob with adjuster for a French time and strike

Is there something obviously broken? You turn the key and nothing happens. The spring does not wind and releases in your hand. The most common reason is a broken click spring or worn click. This is a relatively simple repair that entails taking the movement out of its case.

A loud BANG when you turn the key is definitely not a good sign. Typically the mainspring has broken or let go. It is not as simple as replacing the mainspring. If it breaks it might have taken out other parts with it such as pinions and gear cogs. An inspection and a full servicing of the movement is absolutely necessary.

If the clock has spring barrels the mainspring within the barrel might have become unhooked. Unfortunately this means tearing down the clock, opening the spring barrel and determining what caused it to become unhooked.

Sessions click, brass spring and ratchet

Why does my weight driven clock stop? If it is a new acquisition of a grandfather clock make sure that if it is a chiming clock (Westminster is the most common) the weights are in the correct position. Look underneath the weights for marks indicating their location. If not, the lightest weight goes on the left side.

When bringing up the weights make sure that you do not run them past the stops. You should have a full view of the weights on a weight driven clock once wound.

Antique Ogee and other weight driven shelf clocks often do not come with weights. Eight day clocks typically have heavier 8 or 9 lb weights while 30 hour clocks have lighter 2 1/2 lb or 3 lb weights. Incorrect weights for these clocks will cause them to stop.

Is the weight cord binding? The chord should be just long enough to accommodate the weights. If the chord is too long it might bind while being wound and stop the clock.

Some clocks like a weight driven Vienna Regulators can be adjusted by a screw at the top of the pendulum which moves it in either direction to determine the correct beat.

Gustav Becker two weight Vienna Regulator time and strike wall clock

Obviously, if the weights are resting on the bottom of the base board, the clock will not run.

I hope these tips will help. This article does not cover every possible situation and the problem you are having may be quite unique but if you have a particular question or issue please write.