Introduction
The hour wheel is a key component of the motion works, responsible for rotating the hour hand at the correct rate. If the hour wheel is incorrect—wrong tooth count, wrong tube size, or wrong arbor fit—the hour hand will drift, bind, misalign, or display incorrect time. This guide explains how to choose the correct hour wheel for your mechanical clock.
Understanding What the Hour Wheel Does
Controls hour-hand rotation
The hour wheel rotates once every 12 hours, driven by the minute wheel through the motion works.
Supports the hour-hand tube
The hour hand mounts directly onto the hour wheel’s tube.
Maintains motion-works ratio
Its tooth count ensures the correct relationship between minute and hour hands.
Key Features of Hour Wheels
Tooth count
Must match the motion-works ratio for accurate hour-hand rotation.
Tube diameter
The hour-hand tube must fit the hour hand securely without wobble or binding.
Arbor fit
The hour wheel must rotate freely on its support post or motion-works bridge.
How to Identify the Correct Hour Wheel
Match the tooth count
Even a small difference disrupts the minute-to-hour ratio.
Check the tube diameter
The hour hand must fit snugly without slipping or excessive force.
Verify arbor length and pivot fit
The hour wheel must rotate smoothly on its post without friction or excess play.
Matching Hour Wheels to the Movement
Identify the movement manufacturer
Hermle, Urgos, and Kieninger specify exact tooth counts and tube sizes for each model.
Match the minute wheel
The hour wheel must mesh smoothly with the minute wheel for proper motion-works operation.
Check motion-works bridge compatibility
The hour wheel must align with the bridge or front plate support post.
Common Hour Wheel Materials
Brass hour wheels
Most common and ideal for smooth, low-friction operation.
Steel pinions
Provide durability and long-term wear resistance.
Alloy tubes
Used in modern clocks for improved strength and precision.
Common Mistakes When Choosing Hour Wheels
Incorrect tooth count
Causes incorrect hour-hand rotation or misalignment.
Wrong tube diameter
Leads to slipping, binding, or loose hour-hand fit.
Incompatible arbor fit
Results in poor alignment with the minute wheel or motion-works bridge.
Recommended Internal Links
- How to Choose the Right Clock Minute Wheels
- How to Choose the Correct Clock Cannon Pinions
- How to Choose the Right Clock Center Wheels
- How to Choose the Correct Clock Third Wheels
FAQs
How do I know which hour wheel my clock needs?
Match the tooth count, tube diameter, arbor fit, and pivot length to the original movement.
Why is my hour hand drifting?
The hour wheel may have the wrong tooth count or an incorrect tube fit.
Can I reuse an old hour wheel?
Only if the teeth, tube, and pivots are in excellent condition.
Do hour wheels from different brands interchange?
Only if the tooth count, tube size, and arbor dimensions match exactly.
Why does my hour hand bind when setting the time?
An incorrect hour wheel can cause misalignment with the minute wheel or motion-works bridge.
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