Chapter 8 Machines
237
Pulleys may also be used to transmit motion, increase or decrease
speed, reverse the direction of motion, or change motion through 90°. See
Figure 8-23. These types of pulley systems may be used in cars (fan belt),
upright vacuum cleaners, washing machines, and electrical appliances.
F
R
E
gure 8-21. With a single, movable
pulley, effort equals half the resistance.
The effort moves twice the distance of
the resistance.
gure 8-22. The fixed pulley changes direction of the effort. The movable pulley decreases
the amount of effort required.
Movable
pulley
Fixed
pulley
R
10N
E
5N
MA = = = 2
R
E
10
5
Movable
pulley
Fixed
pulley
R
E
MA = = = 2
R
E
2
1