Belt and Chain Drives Flashcards

An idler pulley in a belt drive system is primarily used to:

Answer: Maintain proper belt tension and prevent sagging

An idler pulley is a non-driven, freely rotating pulley that maintains proper belt tension and guides the belt path without transmitting power itself.

In a compound belt drive, power is transmitted through:

Answer: Multiple belts connecting intermediate shafts in sequence

A compound belt drive uses intermediate shafts with multiple pulleys and belts connected in series, allowing large overall speed ratios that a single belt drive could not achieve.

Which type of chain is most commonly used for mechanical power transmission in machinery and bicycles?

Answer: Roller chain

Roller chains use cylindrical rollers that engage sprocket teeth smoothly and efficiently, making them the most widely used chain type for power transmission.

The pitch of a chain is defined as the:

Answer: Center-to-center distance between adjacent link pins

Chain pitch is the center-to-center distance between adjacent pins, and it must match the sprocket tooth spacing exactly for the chain to engage properly.

A step pulley (cone pulley) arrangement allows the operator to:

Answer: Change the speed ratio by moving the belt to different diameter steps

A step pulley has multiple diameters stacked together, and moving the belt to a different step changes the pulley diameter ratio, thereby changing the speed ratio.

A 6-tooth sprocket drives a 24-tooth sprocket. The driven sprocket rotates at what fraction of the driver's speed?

Answer: One-quarter the speed

Speed ratio for chain drives = driver teeth / driven teeth = 6/24 = 1/4, so the driven sprocket turns at one-quarter the driver's speed.

What is a major disadvantage of belt drives compared to chain drives under heavy loads?

Answer: Belts can slip or creep under heavy or sudden loads

Belt drives depend on friction to transmit power and can slip or creep when loads exceed the belt's grip, while chain drives engage teeth positively and cannot slip.