The efficiency of power transmission is maximum in case of

Explanation:

The power is transmitted from one shaft to the other by means of belts, ropes, chains, and gears.

• The belts and ropes are flexible members which are used where the distance between the two shafts is large.
• The chains also have flexibility but they are preferred for intermediate distances.
• The gears are used when the shafts are very close to each other.
• A chain drive is also called a positive drive because there is no slip.
• If the distance is slightly larger, a chain drive can be used for making it a positive drive.
• Belts and ropes transmit power due to the friction between the belt or rope and the pulley.
• There is a possibility of slip and creep in belts and rope drive and that is why this drive is not a positive drive.

Hence, due to no-slip condition, the chain drive has a maximum efficiency of power transmission.