Posiblemente <gear> en este caso tenga simplemente el significado de dispositivo, mecanismo o unidad.

Por ejemplo en esta definición de "control gear":

control gear
A general term covering switching devices and their combination with associated control, measuring, protective and regulating equipment, also assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended in principle for the control of electric energy consuming equipment.

(GDT)

O en esta página de Internet en la que un "magnetic control gear" se considera suuperado por las prestaciones que ofrece un "electronic control gear" en el campo de la iluminación.

A saber:

Electronic Control Gear Details

In an international effort to reduce the unnecessary wastage of power as well as other resources greater operating efficiences are expected in the design and construction of new buildings. In lighting the advent of electronic control gear has lead to unprecedented gains in the operational efficiency of lighting installations. As this style of control gear now becomes more of a mainstream demand so to has the price reduced, reducing the payback period needed by end users to justify their use against the traditional magnetic control gear.

http://www.advancelighting.co.nz/AdvanceLighting/ProductCata...

Gratas horas de traducción.