How to Choose the Correct Anniversary Clock Suspension Spring Length for Kieninger & Obergfell Parts Carriage

If you own a Kieninger & Obergfell anniversary clock—also known as a 400-day clock—you know how precise its mechanism is. One of the most common repairs is replacing the suspension spring, a thin wire that attaches the pendulum assembly (carriage) to the clock movement. The correct suspension spring length is critical for proper timekeeping. Using the wrong length can cause the clock to run fast, slow, or stop entirely. This guide explains how to determine the correct suspension spring length for your Kieninger & Obergfell parts carriage, so you can keep your clock running accurately for another year (or 400 days).

Understanding the Anniversary Clock Suspension Spring

The suspension spring is a flat, coiled spring that supports the pendulum. In anniversary clocks, the pendulum rotates, and the suspension spring provides the restoring force that keeps the pendulum swinging. Over time, these springs can fatigue, break, or lose their temper, requiring replacement. Kieninger & Obergfell produced many anniversary clocks from the 1950s onward, and their suspension springs come in various lengths to match different carriage sizes and pendulum weights.

Why Length Matters

The suspension spring length determines the effective pendulum length. A longer spring generally makes the pendulum longer, resulting in a slower swing and a slower clock. Conversely, a shorter spring speeds up the timing. The clock must be adjusted so that the pendulum completes exactly one rotation per minute (for most 400-day clocks). Therefore, the suspension spring must be the correct length for the specific carriage and movement combination.

Identifying Your Kieninger & Obergfell Parts Carriage

Before selecting a suspension spring, you need to identify your clock's carriage. The carriage is the metal frame that holds the pendulum balls and hangs from the suspension spring. Kieninger & Obergfell used several carriage designs, but the most common are the standard 4-ball carriage (often called a "four-glass" or "W400" style) and the larger 8-ball carriage. The carriage size and weight influence the required suspension spring length.

Measuring the Old Spring

If you have the original suspension spring, you can measure it:

1. Remove the spring from the clock carefully.
2. Lay it flat on a ruler.
3. Measure the distance from the top of the collet (the small brass fitting at the top) to the bottom of the lower block (where the carriage attaches).
4. Record this length in inches or millimeters.

Typical lengths for Kieninger & Obergfell clocks range from 2.5 inches to 3.5 inches (63.5 mm to 88.9 mm). However, variations exist, so always measure.

Checking the Movement Plate Markings

Kieninger & Obergfell often stamped the movement plate with the clock model number and sometimes the suspension spring length. Look for numbers like "100-xxx" or "104-xxx" on the back plate. A common code is "104-358" or similar. If you find numbers, search for that specific model to determine the correct suspension spring length.

Where to Find Replacement Suspension Springs

Many clock parts suppliers sell suspension springs specifically for Kieninger & Obergfell clocks. They are often categorized by length (e.g., 2.75", 3.0", 3.25"). Some suppliers list part numbers like "H28" or "S122" for common Kieninger springs. You can also find them at clock repair shops or online clock parts retailers. Avoid generic springs unless you are certain of the length.

Using a Suspension Spring Length Chart

Many clock reference books or online guides provide charts linking carriage type to suspension spring length. For example:

• Standard 4-ball carriage: often uses a 2.75" to 3.0" spring.
• Large 8-ball carriage: often uses a 3.0" to 3.5" spring.

But these are rough guidelines. Always verify with your carriage.

How to Install a New Suspension Spring

Installing a suspension spring requires steady hands and small tools. Here are the basic steps:

1. Remove the old spring from the top block (the part attached to the movement) and the lower block (carriage attachment).
2. Set the new spring into the top collet and crimp it lightly.
3. Attach the lower block to the spring, ensuring the carriage hangs straight.
4. Rehang the carriage on the spring, making sure the suspension guard (a thin wire that protects the spring) is properly aligned.
5. Adjust the pendulum regulation nut (if any) to fine-tune the timing.

Fine-Tuning with the Spring

If the clock runs consistently fast or slow after replacement, you may need a slightly different spring length. A clock that runs fast can be slowed by using a longer suspension spring. A clock that runs slow can be sped up with a shorter spring. However, avoid extreme jumps; try a length change of 1/8 inch (3 mm) at a time.

Common Mistakes to Avoid

• Assuming all Kieninger & Obergfell clocks use the same spring: They do not. Even within the same model line, carriage weight variations exist.
• Using a spring that is too long: It may cause the pendulum to wobble or the clock to stop.
• Using a spring that is too short: It may cause excessive stress on the anchor pins and wear out the movement faster.
• Not checking for other issues: If the clock still doesn't run after spring replacement, the problem could be dirt, worn pivots, or mainspring issues.

Final Recommendation

For a Kieninger & Obergfell anniversary clock, always measure the original suspension spring length first. If that is not possible, look up the clock model number. Purchase a suspension spring that matches the length exactly. Quality springs are made of hardened steel and have a consistent thickness. Avoid cheap springs that may be too soft or irregular. If you are unsure, consult a professional clock repair service. With the correct suspension spring length, your anniversary clock will run accurately for many more 400-day periods.