первичный движитель
первичный двигатель (например генератора)
имя существительное 1) [технический термин] первичный двигатель; первичный источник энергии 2) буксир, тягач Синоним(ы): tractor 3) первопричина; движущая сила
noun Etymology: translation of Medieval Latin primus motor 1. a. an initial source of motive power (as a windmill, waterwheel, turbine, or internal combustion engine) designed to receive and modify force and motion as supplied by some natural source and apply them to drive machinery b. a powerful tractor or truck usually with all-wheel drive 2. the self-moved being that is the source of all motion 3. the original or most effective force in an undertaking or work Example: education is…a prime mover of cultural and societal change — R. C. Buck