10 seconde basics mechanical movements description and applications

11. Another method of effecting the same result as 3, without guide-pulleys.

12. Simple pulley used for lifting weights.

In this the power must be equal to the weight to obtain equilibrium.

13. In this the lower pulley is movable.

One end of the rope being fixed, the other must move twice as fast as the weight, and a corresponding gain of power is consequently effected.

14. Blocks and tackle. The power obtained by this contrivance is calculated asfollows: Divide the weight by double the number of pulleys in the lower block ; the quotient is the power required to balance the weight.

15. Represents what are known as White's pulleys, which can cither be made with separate loose pulleys, or a series of grooves can be cut‘in a solid block, the diameters being made in proportion to the speed of the rope ; that is, 1, 3, and 5 for one block, and 2, 4, and 6 for the other. Power as 1 to 7.

16. and 17, Are what are known as Span- ish bartons.

18. Is a combination of two fixed pulleys and one movable pulley.

19, 20, 21, and 22, Are different arrangements of pulleys. The following rule applies to these pulleys :—In a system of pulleys where each pulley is embraced by a cord attached atone end to a fixed point and at the other to the center of the movable pulley, the effect of the whole will be= the number 2, multiplied by itself as many times as there are movable pulleys in the system.