WORK AND MACHINES 



65 



a small weight at F with a gain in speed. In a windlass 

 and a capstan this device is used to gain in force. 



G-ear wheels (Fig. 53) are used in a similar way. If a 

 large wheel runs in a smaller, the gain is in speed ; but 





FIG. 52 



FIG. 53 



if force is applied to the smaller wheel, the larger turns 

 more slowly but exerts greater force. Gear wheels are 

 commonly used in machinery. 



The inclined plane is used for a gain of force at a loss 

 of speed. A plank inclined from the 

 ground to a wagon floor enables a man 

 to get a heavy body into his cart. The 

 more gradual the slant, the more he gains 

 in force required. A wedge (Fig. 54) 

 has two inclined faces. It also gains for 

 us intensity of force at the expense of 

 speed. 



FIG. 54 



Experiment 56. A vise, copy press, thumb- 

 screw, or bolt and wrench may serve to experiment with the 

 screw. For a wheel and axle, any grooved wheel with its axle 



