Block and tackle in the line that either attach to or run through the moving blocks—in other words, the number of supporting rope sections. An ideal block and tackle with a moving block supported by "n" rope sections has the mechanical advantage (MA), where F is the hauling (or input) force and F is the load. Consider the set of pulleys that form the moving block and the parts of the rope that support this block. If there are "n" of these parts of the rope supporting the load "F," then a force balance on the moving block shows that the tension in
Block and tackle blocks. Frictional losses also mean there is a practical point at which the benefit of adding a further sheave is offset by the incremental increase in friction which would require additional force to be applied in order to lift the load. Too much friction may result in the tackle not allowing the load to be released easily, or by the reduction in force needed to move the load being judged insufficient because undue friction has to be overcome as well. A block which is open or can be opened to engage with a bight, without the necessity to thread the