86 Mr HOLDITCH, ON ROLLING CURVES. 



An example is given in figure (24), where k = 0, and the clearing equation (7) 

 becomes 2& 8 =/ s , and equation (8) for determining the radii is therefore 



y/zab^nl, and a = -. (l + \/2n 2 + l), 



2 



6= -.(-1 + V2n 2 +1). 



Hence, for a wheel of eight teeth, which is derived from a curve of four lobes, 



=3 - s n,if*=i. 



= 2-37J 



l 4 = 4-771 

 b m 3-771 ' 



n = 4, and a = 3 - 37] .^ 

 b 



If » = 6, a 7 = 4-77) 

 6 



for a wheel of twelve teeth to turn with the former, and the teeth (or half-lobes) 

 may be described from rules before given. 



The flat sides of the teeth must be a little hollowed out to allow of the free 

 motion of the points, but these have no connection with the rolling sides. 



