For a chain drive, how does increasing the number of teeth on the driven sprocket affect the output speed?

• A. It decreases output speed (increases speed reduction) and increases torque on the chain.
• B. It increases output speed and decreases torque on the chain.
• C. It has no effect on speed or torque.
• D. It only increases efficiency with no change in speed or torque.

Answer: (A)

In a chain drive, the output speed and torque are determined by the gear ratio between the driver sprocket and the driven sprocket. Increasing the number of teeth on the driven sprocket raises this gear ratio (driven teeth divided by driver teeth). A larger ratio means the output turns fewer times for each input revolution, so output speed decreases. The torque on the driven side increases roughly in proportion to the gear ratio, so the chain and driven sprocket handle higher torque (ignoring losses). This combination—slower speed with higher torque—explains why increasing the driven sprocket teeth is the correct effect.