A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). a belt conveyor system is one of many types of conveyor systems. a belt conveyor system consists of two or more pulleys (sometimes referred to as drums); with an endless loop of carrying medium - the conveyor belt - that rotates about them. one or both of the pulleys are powered; moving the belt and the material on the belt forward. the powered pulley is called the drive pulley while the unpowered pulley is called the idler pulley.