Chapter 2.2: How to Diagnose Gearbox Noise Under Variable Speeds? — From STFT Spectrograms to Order Maps & Campbell Diagrams

Fri, 30 Oct 2026 00:00:00 +0000

In our previous chapter, Chapter 2.1: Why Does a Gearbox Ring Multiple Times in a Single Turn? — Shaft Frequencies, Mesh Harmonics, Sidebands & Order Tracking , we explored the four internal physical clocks of a constant-speed gearbox (shaft rotational frequency, gear mesh frequency, symmetric sidebands, and hunting tooth frequency) and introduced the foundational concept of angular resampling (order tracking).

However, the moment you step away from a constant-speed laboratory rig and onto a real factory floor or vehicle test bench, you immediately run into a major challenge: most precision actuators and gear reducers do not operate at a single, steady rotational speed:

8D Quality Report on ANSV | Precision Actuators & Gear Transmission | Tony Chen

Chapter 2.2: How to Diagnose Gearbox Noise Under Variable Speeds? — From STFT Spectrograms to Order Maps & Campbell Diagrams