cog

A cog is a tooth on a wheel that forms part of a gear. A gear is a rotating machine element that engages with another gear to transmit motion and torque. A cogwheel is the wheel that bears the teeth, and the arrangement of gears in a system is called a gear train.

Cogs mesh with matching teeth on mating gears. The number of teeth, their size, and the pitch determine the gear ratio and the direction of rotation. Gears come in several tooth forms, including spur gears with straight teeth, helical gears with angled teeth, and others such as bevel or worm gears, each using corresponding cogs suited to its type.

Materials for cogs include steel, cast iron, brass, and plastics; manufacturing methods range from stamping and casting to forging and precision machining. Proper lubrication and alignment are important to reduce wear on cog teeth and to maintain efficient torque transmission over time.

In idiomatic usage, the phrase “a cog in the machine” describes a person who is a small, interchangeable part of a larger organization or system. The expression can carry neutral, descriptive, or critical connotations depending on context.

Overall, cogs are fundamental elements in many mechanical systems, enabling controlled sequences of motion and power transfer across devices ranging from simple clocks to complex industrial machinery. Their design encompasses considerations of strength, durability, efficiency, and manufacturability to match the specific application.