|block and tackle|
|a hoisting device in which a rope or chain is passed around a pair of blocks containing one or more pulleys. The upper block is secured overhead and the lower block supports the load, the effort being applied to the free end of the rope or chain|
|block and tackle (blŏk) Pronunciation Key
An arrangement of pulleys and ropes used to reduce the amount of force needed to move heavy loads. One pulley is attached to the load, and rope or chains connect this pulley to a fixed pulley. Each pulley may have multiple grooves or wheels for the rope to pass over numerous times. Pulling the rope or chain slowly draws the load-bearing pulley toward the fixed one with high mechanical advantage.