Wheel and axle

Wheel and axle
The type of simple machine which consist of two co-axial cylinders of different diameters which a mounted on the axle.
  
Diameter
diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle.  


Radius 
Radius  is a line segment from the center to the perimeter (surrounding area) of a circle. Half of a diameter is the length of radius.


In wheel and axle radius is the effort distance.
Radius of wheel is denoted by capital r "R" where as radius of axle is denoted by small r "r".


# Generally effort is applied in a big cylinder and load is applied on a small cylinder which means ED  is greater than LD.
Mathematically,
VR = ED 
         LD
      =  Radius of wheel 
          Radius of axle
       =   R 
            r 
Therefore VR of wheel and axle is  
                                                              r  
We know radius of wheel is greater than the radius of axle which makes the VR greater than 1 and more easy by magnification of force.