A pulley is like a wheel and axle^* in which the axle does not move with the wheel. The wheel turns as a rope is pulled across it. Using a fixed pulley (one that does not move) does not produce any mechanical advantage. It only changes the direction of the force^*.

• It is like a first class lever.
• The axle is the fulcrum in this pulley.
• The distances the effort and load move are the same, but in opposite directions.
• The effort and the load are also the same magnitude^*.

A moving pulley does provide a mechanical advantage.

• It is like a second class lever.
• The fulcrum is one edge of this pulley.
• The axle is the load and the effort is the other edge.

A fixed pulley combined with a moving pulley, both with several grooves to wrap the rope around them more than once is called a block and tackle.

• This pulley set can give a large mechanical advantage so that you can lift very heavy loads.
• The mechanical advantage of this system depends on the number of times the rope loops around the pulleys.