The Engine is a Gravity Modulator: How Everyday Machines Redirect the Direction of Gravitational Fall Within the Fundamental Speed Theory

We demonstrate that within the Fundamental Speed Theory (FST), every engine functions as a gravitational modulator by creating a directed gradient in the motion field, locally redefining the direction of gravitational fall. We extend this to a universal principle: every body possesses an effective gravitational constant $G_{\text{eff}}$ and modifies the $G_{\text{eff}}$ of nearby bodies through its kinetic energy density. The required orbital velocity is derived from first principles, and the formula for $G_{\text{eff}}$ is validated against the Sun to within 4.2%. Using Earth's Moon and Phobos as calibration points, we obtain a linear relation between the velocity deficit and the recession rate, with a critical threshold of -97.5%. Applied to 26 moons across six planetary systems, the model predicts that 25 out of 26 moons are receding, including Triton (+7.0 cm/yr), challenging classical tidal theory. We further outline a unified calibration hierarchy extending the framework to planets (Mercury's perihelion shift), stars (S2's Schwarzschild precession), and interstellar objects (3I/ATLAS). Appendix M provides a finite-lag mechanism explaining why planets do not spiral inward. FST explains seven distinct phenomena with a single principle: the modification of $G_{\text{eff}}$ by organized motion. All predictions are falsifiable through astrometric monitoring and laboratory tests.