The term describing the distance a helical gear or worm thread moves along its axis in one revolution is called what?

The correct term for the distance a helical gear or worm thread moves along its axis in one complete revolution is "lead." In the context of gear design, the lead refers to the axial distance that a thread or gear advances in a single turn. For helical gears or worms, each complete rotation results in a linear displacement along the axis of the gear. This concept is crucial for understanding how these components translate rotary motion into linear motion, which is common in various mechanical systems.

The term "lead" is especially relevant because it highlights how helical gears can effectively engage and transmit motion between shafts that are positioned at angles to one another, differentiating them from standard spur gears. Understanding lead is fundamental for engineers when calculating gear ratios and ensuring efficient power transmission in gear designs.