Gear Transmission Mechanisms & Diagnostics in Watchmaking lecture
Description:
Welcome to Chapter 5 of our Swiss Horological Theory course: Gear Transmission Mechanisms in Watchmaking. This comprehensive, master-level lecture provides an end-to-end study of mechanical watch gear trains. From the foundational geometry of a single gear tooth to the advanced diagnostics of live-running movement defects, this video covers the exact curriculum you would find in a premier Swiss watchmaking program.
In this deep dive, we break down the complex kinematics that power mechanical timepieces, divided into three core engineering segments:
Part 1: Kinematics & Movement Architectures
We begin by tracing the flow of energy from the mainspring barrel to the escapement. You will learn the mechanical principles behind idler, speed-increasing (multiplicative), and speed-reducing gear trains. We explore essential horological mathematics, including radius and rotation ratios, calculating balance wheel frequencies (A/h to Hz), and analyzing the differences between standard Centre Wheel and Grande Moyenne movement layouts.
Part 2: Manufacturing Dimensions & Swiss Standards
Watchmaking relies on extreme precision and rigid manufacturing norms. We demystify the critical concept of the "module" and explore the distinct geometric tooth profiles (epicycloid, hypocycloid, involute). You will learn how to navigate and calculate gear dimensions using the major horological standards: NIHS 20-02 and 20-25 for modern production, legacy NHS standards for vintage movement restoration, and EVJ for custom machining.
Part 3: Force Analysis & Advanced Diagnostics
We shift from theoretical math to practical, bench-ready engineering skills. Discover how to mathematically reverse-engineer and rebuild a "lost mobile" using spatial constraints. We analyze the physics of force transmission, calculating torque distribution and the inevitable efficiency losses caused by friction. Finally, we explore professional diagnostic instruments (WTM, Engretest, Variocouple) and teach you how to read waveform signatures to diagnose the two most critical gear pathologies: La Chute (The Drop) and L'Arc-boutement (The Wedge).
Whether you are a horology student preparing for your bench exams, a vintage restoration specialist, or a mechanical engineering enthusiast fascinated by micro-mechanics, this lecture provides the complete mathematical blueprint and diagnostic toolkit required for professional watchmaking.
Key Topics Covered:
• The Pitch Circle & Gear Modules
• Calculation of Alternances per Hour (A/h) & Hertz
• Winding, Minute, and Time-Setting Trains
• NIHS, NHS, and EVJ Manufacturing Standards
• Missing Gear (Lost Mobile) Reconstruction
• Torque, Friction, & The Golden Rule of Horology
• Dynamic Gear Defect Diagnostics