A block and tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift or pull heavy loads.
The pulleys are assembled together to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope is threaded, or reeved, through the pulleys to provide mechanical advantage that amplifies that force applied to the rope.
Hero of Alexandria described cranes formed from assemblies of pulleys. Illustrated versions of Hero's "book on raising heavy weights" show early block and tackle systems.
Read more about Block And Tackle: Overview, Mechanical Advantage, Example Block and Tackle Configurations, Friction, Rigging Methods, More On Mechanical Advantage
Famous quotes containing the words block and, block and/or tackle:
“Being dismantled before our eyes are not just individual programs that politicians cite as too expensive but the whole idea that society has a stake in the well-being of children down the block and the security of families on the other side of town. Whether or not kids eat well, are nurtured and have a roof over their heads is not just a consequence of how their parents behave. It is also a responsibility of society—but now apparently a diminishing one.”
—Richard B. Stolley (20th century)
“Get behind me, Satan! You are a stumbling block to me; for you are setting your mind not on divine things but on human things.”
—Bible: New Testament, Matthew 16:23.
Jesus to Peter.
“Just start to sing as you tackle the thing
That “cannot be done,” and you’ll do it.”
—Edgar Albert Guest (1881–1959)