The concept of free flow conveyor is used in the assembly line with multiple on-line assembly stations and testing stations. The special chains used in this conveyor has rollers on which pallets are carried. The rollers allow the pallet to be stopped at each stations for assembly / testing operations and also in accumulating with out stopping the conveyor. The mechanical or pneumatic stoppers are used to stop the pallets. These conveyors ensure high productivity and preferred solutions in assembly plants.