There are four types of engine pulleys; crank pulleys, accessory pulleys, idler pulleys and tensioner pulleys. The crank pulley is the drive pulley, which is attached to the crankshaft. Accessory pulleys are attached to alternators, air pumps etc. Idler pulleys spin freely and are not attached to any accessories nor the crankshaft, they simply aid in maintaining the configuration of the belt’s path. Tensioner pulleys are similar to an idler, but they have a spring type mechanism to provide proper tension on the belt. CTP offers all types of pulleys, designed and manufactured to run true and to last for thousands of maintenance free hours.