Tensioner, idler, and damper pulleys maintain proper belt tension and system harmonic control within serpentine and timing drive systems. These components are located along the belt’s path, guiding and stabilizing operation. Tensioners utilize spring-load or hydraulic mechanisms for automatic adjustment, compensating for belt stretch and wear. Idler pulleys freely rotate to alter belt routing and reduce bending stress. Dampers, specifically torsional vibration dampers, minimize harmonic resonance from the crankshaft, protecting engine components.