Mechanical engineeringLesson 2 of 3 in the course Machine design

Gear Systems: Types, Geometry, Operation, and Design

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Gears transmit rotation and torque through interlocking teeth. This lesson introduces their basic parts, their effects on speed and torque, and the role of gear trains in machines.

A gear, or gearwheel, is a rotating machine part with teeth that engage compatible teeth on another gear or component. The teeth may be formed directly in the gear or made as separate pegs. A wheel with inserted pegs is often called a cogwheel; a cog can mean an individual tooth or, informally, the whole gear.

All flashcards

What is a pitch circle?
A theoretical reference circle used to describe how meshing gears behave.
What is backlash?
The clearance between meshing teeth that must be taken up when rotation reverses.
What is a cage gear?
A gear that uses cylindrical rods arranged around an axle as teeth.
What makes a gear train epicyclic?
At least one gear axis moves during operation.
How does a magnetic gear transmit torque?
Through magnetic fields rather than tooth-to-tooth contact.

Quiz questions

  1. When two external gears with parallel axes mesh, how do they rotate?Answer: In opposite directions.
  2. What force is produced along the shaft by the angled teeth of a helical gear?Answer: Axial thrust.
  3. Which gear type is suited to transmitting motion between intersecting axes?Answer: Bevel gears.
  4. What does backlash cause when a gear drive reverses direction?Answer: Lost motion while the clearance between teeth is taken up.
  5. A 10-tooth gear drives a 30-tooth gear. Ideally, what happens to output speed and torque?Answer: Speed falls to one-third; torque rises threefold.

Based on the Wikipedia article Gear, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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