Introduction
Gears and pinions transfer power through the clock’s train. Choosing the wrong tooth count, module, or arbor size leads to binding, skipping, poor depthing, or a clock that won’t run at all. This guide explains how to choose the correct gears and pinions for your mechanical clock.
Understanding What Gears & Pinions Do
Transfer power through the train
Each wheel and pinion pair advances the next stage of the movement.
Set the clock’s gear ratios
Incorrect tooth count disrupts timing and chime sequencing.
Maintain proper depthing
Gears must mesh at the correct distance to avoid binding or skipping.
How to Identify the Correct Gear
Count the teeth accurately
Miscounting even one tooth results in an incompatible gear.
Measure the gear’s module
Module defines tooth size. Gears with different modules cannot mesh.
Measure the arbor hole diameter
The gear must fit the arbor snugly without wobble.
How to Identify the Correct Pinion
Count the pinion leaves
Pinions use leaves instead of teeth. Count carefully to avoid mismatch.
Match the module to the gear
Gear and pinion must share the same module to mesh properly.
Check the pinion’s arbor diameter
The pinion must fit the arbor securely without excess play.
Matching Gears & Pinions to the Movement
Identify the movement manufacturer
Hermle, Urgos, and Kieninger use different modules and tooth profiles.
Match the gear ratio
Replacing a gear requires matching the original tooth count and pinion leaves.
Check for wear on mating components
Worn pinions or bent arbors cause premature gear wear.
Common Gear & Pinion Materials
Brass gears
Most common. Provide smooth operation and long life.
Steel pinions
Used for durability and strength in high-load areas.
Cut vs. stamped gears
Cut gears offer better precision; stamped gears are more economical.
Common Mistakes When Choosing Gears & Pinions
Mixing modules
Gears with different modules cannot mesh correctly.
Incorrect tooth or leaf count
Even a one-tooth difference disrupts the entire gear train.
Ignoring arbor diameter
Gears that fit loosely cause wobble and poor depthing.
Recommended Internal Links
FAQs
How do I know what gear my clock needs?
Count the teeth, measure the module, and match the arbor hole diameter.
Can I replace a gear with one that has a different tooth count?
No. Changing tooth count alters the gear ratio and disrupts timing.
Do all clocks use the same module?
No. Module varies by manufacturer and gear position.
Why does my gear bind when installed?
The module may be incorrect, or the gear may be off-center on the arbor.
Can I mix brass gears with steel pinions?
Yes. This is the standard configuration for most mechanical clocks.
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