The tachometer works on the principle of centrifugal force acting on rotating masses. When the model’s handle is turned, a reducer increases the rotational speed transferred to a pair of weights. As RPM rises, these weights move outward due to centrifugal force, shifting a connected axle and flywheel assembly. The pointer mechanism attached to this axle deflects proportionally, indicating the measured speed on the dial mirroring how real mechanical tachometers measure RPM before digital sensors existed.

This physical demonstration shows how rotational speed, torque load, and mechanical strain are monitored in engines. Tachometers help prevent overloading, guide gear‑shifting decisions, and maintain optimal performance in vehicles and machinery. The Ugears model clearly illustrates this relationship and even allows users to explore gear‑ratio effects when paired with the Variator system, providing a vivid understanding of transmission dynamics.