engranes

Engranes, or gears, are mechanical components consisting of toothed wheels that mesh to transfer motion and torque between rotating shafts. By meshing, they change rotational speed and torque while enabling direction changes. Common types include spur gears with straight teeth, helical gears with angled teeth for smoother operation, bevel gears for power transfer between non-parallel shafts, worm gears for high reduction ratios, and rack-and-pinion assemblies that convert rotary motion to linear motion. Gear systems can be simple or compound, with configurations such as planetary (epicyclic) gear trains used to achieve large reductions in compact spaces.

Key design parameters include the number of teeth, pitch diameter, module or diametral pitch, addendum, dedendum, clearance, center distance, and gear ratio. The gear ratio equals the quotient of output to input teeth, and multi-stage trains multiply ratios. Materials range from alloy steels and cast iron to brass and engineering plastics; gears are commonly heat-treated to improve hardness and wear resistance. Manufacturing methods include hobbing, shaping, milling, grinding, and finishing to achieve precise tooth profiles and surface finishes. Proper lubrication, alignment, and controlled backlash are essential for efficiency and longevity.

Engranes are pervasive in industry and daily life, from automotive transmissions and industrial gearboxes to clocks, robotics, wind turbines, and consumer devices. The Antikythera mechanism and later machinery illustrate the long historical development of gearing, which remains central to torque transmission and speed control in modern engineering.