284: THE MECHANICAL POWEKS. 



When the power does not run parallel to the plane, draw 

 a line perpendicular to the direction of the power's action 

 from the end of the base line (at the back of the plane), and 

 the intersection of this line on the length will determine the 

 length and height of the base. 



THE WHEEL AND THE AXLE. 



The power multiplied by the radius of the wheel is equal 

 to the weight multiplied by the radius of the axle. 



As the radius of the wheel is to the radius of the axle, so 

 is the effect to the power. 



To find the weight a given tractile force or power will 

 move on a wheel and axle of given radii. 



KULE. Multiply the tractile or drawing force by the 

 radius of the wheel, and divide the product by the radius of 

 the axle. 



EXAMPLE. What weight will a tractile force of 250 Ibs. 

 draw on a wheel (or wheels) of a radius of 3 feet : radius of 

 axle 4 inches ? 



SOLUTION. 250 Ibs., tractile force, x 36 inches, radius 

 of wheel, = 9000-^-4 inches, radius of axle, 2250 Ibs. Ans. 



To find the tractile force required to move a gi/ven weight 

 on a wheel and axle of given radii. 



