Belts for upright vacuums fit specific upright-vacuum brands or models. They're used to replace broken or worn belts that no longer turn the vacuum's brush roller.,Vacuum belts rotate the brush roller of a vacuum cleaner to lift embedded dirt and dust from carpet fibers. They connect the roller to the motor shaft to transfer power for spinning the roller. These belts are used as replacements for snapped or stretched belts that can no longer turn the roller.