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, 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)
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—Quentin Crisp (b. 1908)
“Just start to sing as you tackle the thing
That “cannot be done,” and you’ll do it.”
—Edgar Albert Guest (1881–1959)