Which pulley adjusts the amount that the belt wraps around the drive pulley?

• A. Snub
• B. Idler
• C. Tension
• D. Sheave

Answer: (A)

The concept being tested is how belt wrap around the drive pulley is controlled. Belt wrap—the portion of the belt that stays in contact with the drive pulley—affects friction and grip. A snub pulley is a small auxiliary pulley placed near the drive pulley to steer the belt path in a way that increases the contact angle around the drive pulley. By adding or adjusting this extra pulley, you can increase the wrap and therefore improve belt grip and reduce slip under load. The other options don’t purposefully change how much belt contacts the drive pulley: an idler mainly guides the belt, a tension pulley changes tension rather than wrap, and a sheave is the pulley itself without altering wrap.