Introduction
The hour tube is the hollow shaft that carries the hour hand and interfaces with the hour wheel. If the hour tube is incorrect—wrong diameter, wrong depth, or wrong engagement height—the hour hand will slip, bind, wobble, or display incorrect time. This guide explains how to choose the correct hour tube for your mechanical clock.
Understanding What the Hour Tube Does
Supports the hour hand
The hour hand mounts directly onto the hour tube, which rotates once every 12 hours.
Engages with the hour wheel
The tube fits over the hour wheel’s arbor or post to transfer motion.
Controls hand height and spacing
Tube depth determines how the hour hand sits relative to the minute hand and dial.
Key Features of Hour Tubes
Tube diameter
Must match the hour hand’s mounting hole for a secure fit.
Tube depth
Determines hand height and prevents rubbing against the dial or minute hand.
Engagement height
The tube must align with the hour wheel for smooth rotation.
How to Identify the Correct Hour Tube
Match the tube diameter
The hour hand must fit snugly without slipping or excessive force.
Check the tube depth
Incorrect depth causes rubbing, wobble, or poor hand alignment.
Verify engagement with the hour wheel
The tube must sit at the correct height to mesh with the hour wheel’s drive.
Matching Hour Tubes to the Movement
Identify the movement manufacturer
Hermle, Urgos, and Kieninger use specific tube diameters and engagement heights.
Match the hour wheel
The tube must fit the hour wheel’s post or arbor without friction or excess play.
Check dial spacing
The tube must position the hour hand at the correct height relative to the dial.
Common Hour Tube Materials
Brass hour tubes
Most common and ideal for smooth, low‑friction rotation.
Steel reinforcement sleeves
Used in some movements for added strength.
Alloy tubes
Provide improved wear resistance in modern clocks.
Common Mistakes When Choosing Hour Tubes
Incorrect tube diameter
Causes slipping, binding, or loose hour‑hand fit.
Wrong tube depth
Leads to rubbing against the dial or minute hand.
Incompatible engagement height
Results in poor alignment with the hour wheel and incorrect hand rotation.
Recommended Internal Links
- How to Choose the Right Clock Hour Wheels
- How to Choose the Correct Clock Motion‑Works Bridges
- How to Choose the Right Clock Minute Wheels
- How to Choose the Correct Clock Cannon Pinions
FAQs
How do I know which hour tube my clock needs?
Match the tube diameter, depth, and engagement height to the original movement.
Why is my hour hand loose?
The hour tube may have the wrong diameter or worn mounting surface.
Can I reuse an old hour tube?
Only if the tube is straight, unworn, and fits the hour hand securely.
Do hour tubes from different brands interchange?
Only if the tube diameter, depth, and engagement height match exactly.
Why is my hour hand rubbing the dial?
An incorrect tube depth or engagement height can cause improper hand spacing.
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