What are the three pulleys?

When classifying pulley systems by their fundamental mechanical configurations in basic physics and engineering education, textbooks typically focus on three primary types: the fixed pulley, the movable pulley, and the compound pulley system. A fixed pulley changes the direction of the force without reducing the effort needed. A movable pulley moves with the load, cutting the required lifting effort in half by sharing the weight across two rope segments. A compound pulley combines fixed and movable wheels to achieve high mechanical advantage, allowing heavy industrial loads to be lifted with minimal human input force across various mechanical applications.

When mechanical physics and educational curriculums classify pulleys into three primary operational configurations, they typically refer to: 1) Fixed pulleys, which feature a stationary axle mounted to a rigid support structure, used solely to change the direction of an applied pulling force rather than reducing weight effort; 2) Movable pulleys, where the axle is attached directly to the moving load itself, providing a mechanical advantage that cuts the required lifting force in half; and 3) Compound pulleys (or block and tackle systems), which integrate multiple fixed and movable wheels working together in tandem to lift extremely heavy loads with minimal human effort. You can verify these foundational classifications through classical mechanics textbooks and physics educational curricula.