A pulley used to increase arc of contact on the drive pulley is:

The use of a snub pulley is to increase the arc of contact on the drive pulley by changing the path of the belt. This adjustment allows for better grip and more efficient power transfer between the belt and the drive pulley. By creating additional contact with the drive pulley, the snub pulley enhances the belt's friction against it, reducing slippage and improving overall system performance.

In many applications, achieving a greater arc of contact is crucial for maintaining effective transmission of power, especially in scenarios where the distance between pulleys is significant, or where variable loads are involved. The strategic placement of snub pulleys can optimize performance and enhance the reliability of the transmission system by ensuring that the belt remains engaged with the drive pulley as much as possible.