Speed reducers, gear reducers, and torque increasers are all correct industry terms for gearboxes. They come in many types, shapes, and configurations with various internal gearing to achieve the reduction of speed. Gearboxes come with helical gears, worm gears, planetary gears, miter gears, bevel gears, and even cycloidal gears. Helical gear reducers are available in concentric shaft, parallel shaft, and shaft mount styles. Worm gear boxes offer a multitude of ratios in a compact space and are combinable in single, double, triple, and even quadruple reductions. If a higher degree of efficiency is desired, a planetary or cycloidal reducer may be better for your application. Miter and bevel reducers have lower ratios and offer compact right angle applications a popular option. Some brands that may be available to you are Grove Gear, Hub City, SEW Eurodrive, Grant, Winsmith, Rex, Sumitomo, David Brown Radicon, Textron, Dodge and Falk.