What is a block and tackle?
When working with ropes, pulleys are very useful to create a mechanical advantage, i.e. multiply the force applied to move a load. With the right number of pulleys, it is possible to move loads heavier than two, three and even four times the force applied.
A set of ropes and pulleys arranged to gain mechanical advantage is called a tackle. We also talk about block and tackle (double, triple, quadruple, etc.).
To generate a mechanical advantage, at least one pulley must be attached to the load.
Note that when using pulleys to increase the force, the pulling speed is reduced by the same factor.
View the diagram examples to help set you up: