Full definition
A single continuous Poly-V (micro-V) belt that drives multiple engine accessories in a serpentine path around the crankshaft pulley, alternator, A/C compressor, water pump, power steering pump, and automatic tensioner. Profile: typically PK (3.56 mm rib pitch) with 6-8 ribs (6PK, 7PK, 8PK designations). EPDM has replaced neoprene as the standard compound, offering 60,000-100,000 mile service life versus 30,000-50,000 for CR. Wear is measured by rib depth (replace at <90% of original). Automatic spring-loaded tensioners maintain correct force. Per SAE J1459. Brands: Gates, Continental, Dayco, Bando. A single serpentine belt replaced 3-5 individual V-belts in modern engines.