Friction wheel 1 rotates about fixed axis A and the elements of its external cylindrical surface a contact the elements of external cylindrical surface b of friction wheel 2 which rotates about fixed axis B. The transmission ratio between wheels 1 and 2 without slippage is i₁₂=-(n₁/n₂)=-(R₂/R₁) where n₁ and n₂ are the speeds (in rpm) and R₁ and R₂ are the radii of friction wheels 1 and 2. Rotation is transmitted between wheels 1 and 2 by friction between surfaces a and b. The torque on driving wheel 1 is related to torque M₂ transmitted to driven wheel 2 by the equation Q≥(M₁x)/(fR₁)=(M₂x)/(fR₂) where Q is the normal force applied between the wheels (along line AB), x=1.5 to 2 is the traction assurance factor and f is the coefficient of sliding friction between surfaces a and b.
$3360$SmF,3L$