PMMI Mechanical Drives Practice Test

The key idea is positive engagement between the belt and pulley through teeth. A belt with teeth on its inner surface meshes with matching teeth on the pulley, so rotation of one shaft forces the other to rotate in exact lockstep. That teeth-to-tooth contact prevents any slip and preserves a fixed timing relationship between shafts, which is essential whenever precise phase and speed ratios are required. That’s why a timing belt is the best fit. Its toothed design creates a synchronous drive, keeping the shafts in sync even under changing loads. In contrast, a V-belt relies on friction between smooth belt and pulley surfaces, which can slip if torque or speed changes occur. A flexible coupling handles misalignment and some vibration but doesn’t provide the locked, tooth-driven connection needed to maintain timing. And hinge belt isn’t a standard belt type for timing applications.