Plain English Meaning

A system that uses pressurized fluid working together with moving mechanical parts to sense what is happening and adjust something automatically — no electronics involved.

Full Definition

Describing a system or device that combines hydraulic action (pressurized fluid) with mechanical linkages (levers, cams, gears, springs) to sense conditions and control an output. In aircraft powerplants, hydromechanical commonly refers to fuel control units that meter fuel to the engine using fluid pressure signals and mechanical components, without electronic computation.

Context Anchor

Seen in aircraft engine and fuel-control discussions, especially when describing a hydromechanical fuel control unit.

Derivation

Built from 'hydro' (Greek hydor, water — used generally for fluid) and 'mechanical' (Greek mēkhanē, machine). The term simply names the two working parts of the system: fluid pressure plus mechanical linkages.