3

A "Pulley" and a "Wheel and axle" seem much similar to each other. What is their actual difference and what are their precise definitions?

My understanding of the two terms is much relied on the context of Simple machines. The wikipedia articles of the two terms provide a definition which makes them seem very similar. But since simple machines are considered (by ancient greeks) as six distinct different basic machines then they must have an important difference.

I'm not sure, but maybe modern treament of mechanical machines in terms of "Linkage synthesis" could give a better explanation. If it's possible, please explain the differences and the definitions both in the context of "Simple machines" and "Linkage synthesis" methods.

Hamed Begloo
  • 139
  • 1
  • 2
  • 5

1 Answers1

1

The construction of a "pulley" and a "wheel and axle" can be similar or even same. But in the simple machines classification their purposes differ:

  • Pulley is used to change the direction of a rope or a chain. The actual rotation of the pulley wheel is a side effect.
  • Wheel and axle are used to amplify rotational force. The force can be provided through a rope wrapped around the wheel, but the change of direction is a side effect.

For example, a chain sprocket is an example of wheel and axle, while a chain idler would be an example of a pulley.

jpa
  • 1,943
  • 9
  • 12