Gearboxes

Gearboxes, or gear reducers, are mechanical assemblies that transmit power between a source and driven machinery while modifying speed and torque. They are designed to convert high speed, low torque from a motor or engine into lower speed and higher torque required by the driven equipment, though some configurations can increase speed at the expense of torque when paired with different gear sets. The primary purpose is to provide the appropriate speed-torque combination for the load while preserving adequate power transmission.

Most gearboxes contain gears mounted on shafts inside a rigid housing, with a lubrication system to reduce wear and heat. Gears transmit torque through meshing teeth, and the overall speed reduction or multiplication is determined by gear ratios defined by gear sizes and arrangements. Losses arise from bearing friction, gear tooth contact, lubrication, seals, and cooling, so efficiency depends on design, load, and maintenance.

Common gear types include spur gears (straight teeth), helical gears (angled teeth for smoother operation), bevel gears (intersecting shafts), and worm gears (a worm and wheel arrangement for high reduction in compact form). Planetary gearboxes use a sun, planet, and ring gear arrangement to achieve high torque in a compact package, widely used in robotics and precision drives. Other specialized configurations, such as harmonic or cycloidal drives, appear in niche applications.

Applications span automotive transmissions, industrial drives (conveyors, mixers, presses), wind turbine gearboxes, robotics, and aerospace. Key selection criteria include torque rating, speed, required gear ratio, backlash, efficiency, thermal capacity, lubrication method, sealing, and mounting arrangement. Proper maintenance—timely lubrication, monitoring for wear and noise, and alignment checks—extends gearbox life and reliability.