Chain:

The belt drive is not a positive drive due to creep and slip. The chain drive is a positive drive. As belts, chains can be utilized for larger centre distances. They are made of metal and because of this chain are heavier than the belt but they are flexible like as belts. It also needs lubrication from time to time. The lubricant prevents chain from rusting & reduces wear.

The chain and chain drive are illustrated in Figure. The sprockets are utilized in place of pulleys. The projected teeth of sprockets fit in the recesses of the chain. The distance among roller centers of two neighbouring links is called pitch. The circle passing through the pitch centers is known pitch circle.

                        (a)                                                                                              (b)

                               (c)                                                                       (d)

   Chain and Chain Drive

Assume 'φ' be the angle created by the pitch of the chain, and 'r' be the pitch circle radius, then

p = 2r sin φ/2 or,

r = p/2 cosec (φ/2)