Block and Tackle
A set of pulleys assembled so they rotate independently on the same axle form a block. Two blocks with a rope attached to one of the blocks and threaded through the two sets of pulleys form a block and tackle.
A block and tackle is assembled so one block is attached to fixed mounting point and the other is attached to the moving load. The mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block.
In the diagram on the right the mechanical advantage of each of the block and tackle assemblies shown is as follows:
- Gun Tackle: 2
- Luff Tackle: 3
- Double Tackle: 4
- Gyn Tackle: 5
- Threefold purchase: 6
Read more about this topic: Pulley
Famous quotes containing the words block and/or tackle:
“The chess pieces are the block alphabet which shapes thoughts; and these thoughts, although making a visual design on the chess-board, express their beauty abstractly, like a poem.... I have come to the personal conclusion that while all artists are not chess players, all chess players are artists.”
—Marcel Duchamp (1887–1968)
“Play with your fancies: and in them behold
Upon the hempen tackle ship-boys climbing;
Hear the shrill whistle which doth order give
To sound confused; behold the threaden sails
Borne with th’ invisible and creeping wind.”
—William Shakespeare (1564–1616)