MEPX
Chapter 6 of 12All chapters
  1. 1What engineers do
  2. 2The design process
  3. 3Forces and loads
  4. 4Stress, strain and materials
  5. 5Structures
  6. 6Mechanisms
  7. 7Electrical basics
  8. 8Energy in machines
  9. 9Manufacturing and tolerances
  10. 10Safety factors and failure
  11. 11Testing and standards
  12. 12Responsibility

Chapter 6 of 12

Mechanisms

Levers, gears and torque.

Turning force

Torque is force times distance from the pivot, which is why a longer spanner loosens a tighter bolt with the same push. A lever trades distance for force in exactly the same way.

  • Gears trade speed against torque: a smaller gear driving a larger one turns slower with more force.
  • Nothing multiplies energy. Everything multiplies force at the cost of distance.

Friction and wear

Friction is what makes machines lose energy as heat and what makes them wear out. Bearings, lubrication and material pairing are most of the answer.