400-Day "Anniversary" Clocks


This Guide was written for your use, information, and enjoyment. It includes some background information on this type of clock, information on how to set and wind it, and some info on how to care for it. However, for legal reason, I must point out that you use this guide at your own risk.

This guide may not be reprinted in whole or in part without my consent. However, feel free to print out a copy for your own, personal use.




Anniversary clocks have been around for some time, but they really became popular in the 1950's - hence, most of the anniversary clocks you will find were made since then. Unfortunately, I don't believe wind-up versions (called 400-day clocks) are still made. Quartz regulated, battery powered clocks have taken their place. While some may call this "progress", putting a battery in once a year just doesn't have the charm of winding a good old-fashioned clock!

What are the parts:

Rather than cover the whole clock, I'll just cover the parts you might normally deal with. I'll start with the suspension spring. This is a thin, flat piece of spring steel that suspends the clock's weights (pendulum) and twists as the pendulum rotates. Avoid touching the spring, and NEVER bend or kink it in any way - or your clock will probably stop. It is the most critical and fragile part of the clock.

The pendulum consists of a spindle and usually 3 or 4 weights that are suspended over a cup on the base of the clock. The spindle should freely twist over the cup without touching the cup's sides or bottom. Attached to the spindle are arms that each hold a weight away from the spindle at a distance set by the adjustment wheel. The adjustment wheel is, as the name implies, used to adjust the timing of the clock. Turning the wheel moves the weights either closer to or farther from the center of the pendulum, causing it to turn faster or slower respectively. The purpose of the weights is to provide momentum to slow down the twisting of the spring.

There are usually one or more leveling feet underneath the clock. These are used to ensure the clock is level (i.e., the spindle does not touch the sides of the cup). If the clock is not level, the feet can be adjusted accordingly.

The winding arbor (shown in the left figure below) is the square post extending from the back of the clock. The clock key is inserted over this post for winding.

Where to place your clock:

Anniversary clocks are generally light weight and easily moved, even by simple dusting. If the clock is jarred such that it loses an impulse (misses a "tick"), the pendulum might not regain the lost impulse, which means the clock will eventually stop (this may take several minutes). For example, someone could bump the clock and leave the room while the pendulum was still twisting, and find the clock stopped when he/she returns later - and usually will blame the clock for stopping. A sizable bump can bend or kink the suspension spring. If this happens, the clock will probably stop and you will not be able to keep it going. Repair is required in this case.

The moral of all this is that you should place your clock on a firm, flat, and level surface that is not subject to vibration or jarring. Once there, you should avoid moving it if possible. If you must move the clock, move it slow and steady, always holding it level. After moving (or if you bump it), listen for a "tick" at both ends of each pendulum rotation. Suggested clock locations might be on a mantle, on a buffet, or in a curio cabinet. Less desirable locations would be on tables, night stands, or light dressers that are easily moved or bumped, or may be subject to pets and small fingers.

How to transport and set up your clock:

Whenever you move a 400-day clock more than a few feet you should lock the pendulum to prevent it from swinging around in the case. An unlocked, swinging pendulum can kink or break the suspension spring, or even break the glass dust cover.

Unfortunately, each clock manufacturer has designed a different method to lock the pendulum, so I can't cover them all here. Some clocks trap the pendulum by restraining the top of the spindle, while others trap the bottom. In most cases, however, the idea is to lift the pendulum bob and trap it to 1) keep it from swinging from side to side, and 2) take the load off the suspension spring. As an example, the Kundo® brand clock normally traps the spindle at the top as illustrated and described below:

Gently lift the spindle so that the spindle locking slot is in line with the locking lever. While holding the spindle at this level, rotate the locking lever until it enters and rests firmly inside the locking slot. Slowly release the spindle. All the pendulum weight should now be resting on the locking lever, and the suspension spring should be slightly slack. The clock can now be safely moved. (This is just an example - your clock's locking mechanism may be much different.)

Place the clock in its intended location before unlocking the pendulum. To release the pendulum, gently lift the spindle so that when the locking lever is released the pendulum won't fall - jerking the suspension spring. While holding the spindle, rotate the locking lever out of the locking slot and slowly lower the spindle until the suspension spring supports the pendulum weight.

Anniversary clocks must be level before they will operate, so it may be necessary to relevel the clock after it is moved. Check to ensure that the spindle does not touch the sides or bottom of the cup over which it is suspended. If it does touch the sides, raise or lower the leveling feet such that the spindle is centered as shown in the diagram below. If it touches the bottom, you should consult your clock repairman.

How to wind and start your clock:

As the name implies, the anniversary clock must be wound (at least) once each year. Many of these clocks will actually make it a whole year, but it is not uncommon for them to only last 8 or 9 months. The clock will probably begin to run slower as the year drags on. I recommend winding twice a year. As the oil in the clock gets old or dust gets in, the clock may not make it even 6 months. If your clock doesn't run four months between windings you should have it cleaned by a qualified repairman.

To wind your clock, hold the clock steady by firmly grasping the base or clock support pillars. Insert the clock key over the winding arbor and wind until it becomes difficult to turn the key. Never over-wind, as this can break the main-spring. Common sense is a good rule - if you are winding and it begins to rapidly feel more difficult to wind, so stop winding.

To start the clock, gently push one of the weights such that the pendulum twists at least 270°. Be careful not to push too hard or the pendulum will swing from side to side rather than twist (a small amount of sideways movement is normal, but should be minimized). After pushing and releasing the pendulum, watch and listen to the clock. You should hear a "tick" at both ends of the pendulum twist.

To set the correct time, simply use your finger to turn the minute hand until you reach the correct time. Since most anniversary clocks do not chime, you can turn the minute hand in either direction to reach the correct time. Do not turn the hour hand, as this can damage the clock.

How to adjust and care for your clock:

To adjust the clock, first wait for the pendulum bob to come to the end of a twist. Just as the pendulum stops, lightly grasp the weight arm as shown in the picture below.

The adjustment wheel may have markings indicating which direction to turn to make the clock run faster or slower. The direction to make the clock run faster is often marked "+", "A" (advance), or "F" (fast). The direction to adjust the clock slower is often marked "-", "R" (retard), or "S" (slow). Turn the wheel in the desired direction, making very small adjustments. When adjustments are complete, let go of the weight arm - the clock should start by itself. Next, adjust the time setting by moving the minute hand as described earlier. Monitor the clock for a week or more before making further adjustments (sooner if the clock gains or loses more than three minutes a day). Once adjusted, there should be little or no need to touch the clock unless, over time, the clock gains or loses a little. If this happens, you can simply reset the minute hand or try to adjust the timing better. Keep in mind that you can not make timing "perfect" because outside influences, such as room temperature changes, vibration, and other factors not always under your control can affect how fast the clock runs.

Care for your clock by washing the glass dome in mild soap and water. The clock base and frame can be cleaned by simple dusting. Never attempt to clean the clock movement unless you have the right materials and experience - this is best left to the clock repairman.

What makes it tick (In case you wanted to know):

Most 400-day clocks operate on the same principle: The clock has a series of gears that try to rotate to unwind the main spring. As the last gear in the series tries to turn, it hits a finger extending from a c-shaped arm called the "verge". As the gear tooth pushes the finger out of the way, a finger on the opposite side of the verge moves into the way of another tooth. As the gear repeatedly pushes the two fingers out of the way, it rocks the verge from side to side, which pushes an arm connected to the suspension spring. This causes the spring to twist. The suspension spring must twist once in both directions for each gear tooth to pass.

How fast the spring twists depends on the pendulum's momentum. A series of 3 or 4 weights are suspended from the spring, and they rotate along with the spring's twisting. We speed up or slow down the clock by varying how far the weights extend from the center of the twist. The farther the weights are from center, the more momentum the weights have, and the slower the clock will run. The closer the weights are to the center, the faster the clock will run. Hence, we "regulate" the clock speed by changing how far out the weights are. Most 400-day clocks twist the weights (called the pendulum "bob") at the rate of 8 turns a minute, but 6 and 10 turns are also common.

That's how the main-spring slowly unwinds so that one gear tooth at a time can pass at a controllable rate. From here it is simply a matter of putting hands on the gears that are turning at the right speed to rotate once an hour and once in 12 hours.

When does your clock need service:

The pendulum bob should rotate at least 270° on each swing. If it does not continue running after repeated attempts to start it, it probably needs service. Anniversary clocks may run a whole year, but as the oil gets old and dust accumulates, the run time will decrease. If this bothers you, you may wish to have your clock cleaned and oiled. Don't try to oil it yourself unless you have a good quality clock oil. Household oils, and even WD-40®, will leave deposits that gum up clocks. If your clock will not run at least four months you should have it cleaned. Continued use of a clock that needs cleaning will cause wear to the gears and end plates - which can be expensive to repair. Generally, you should last at least three years on a good cleaning - often many more than that.

If the suspension spring develops a kink or bend, it should be replaced. If the spindle touches the bottom of the cup, the spring must be adjusted or replaced. If you hear a "snap" while winding, this does not necessarily indicate a problem unless after the snap, winding becomes much easier and goes on seemingly forever. If this is the case, the mainspring has probably broken, and must be replaced.

Final Note:

Despite how delicate this type of clock is, if it is kept in a safe, solid location and is not jarred, it will be a beautiful, virtually maintenance-free asset for you to treasure for years to come. You may wish to make winding an annual event, such as on your wedding anniversary, Christmas, or your birthday.


I hope this information is of value to you! Enjoy!



Page copyright © 1999 through present date by Steven R. Osburn. All rights reserved. Last modified on 2 January 2000.