Gears:

Gears are also utilized for power transmission. This is accomplished through the successive engagement of teeth. The two gears transmit motion through the direct contact as chain drive, gears also provide positive drive.

The drive among the two gears can be defined by using plain cylinders or discs 1 and 2 with diameters equivalent to their pitch circles as illustrated in Figure. The point of contact of the two pitch surfaces shell contains velocity with the common tangent. Because there is no slip, thus, definite motion of gear 1 may be transmitted to gear 2 or vice-versa. The tangential velocity 'V_p' = ω₁ r₁ = ω₂ r₂ where r₁ & r₂ are pitch circle radii of gears 1 & 2, respectively.

                     Gear Drive

or,

N₁  r₁  = N ₂  r₂

or,

As, pitch circle radius of a gear is proportional to its number of teeth (t).

here t₁ & t₂ are respectively the number of teeth on gears 1 and 2,.