Method of transporting workpieces in assembly line

A method of transporting workpieces in an assembly line, comprising the steps of:

• positioning a first self-propelled transporting member and a second self-propelled transporting member at a starting end of an assembly line, wherein said first transporting member is provided with a first workpiece thereon and said second transporting member is provided with a second workpiece thereon, and said first workpiece requires a different amount of assembling man-hours than does said second workpiece;
• determining a transporting pitch to be established between said first transporting member and said second transporting member as said first transporting member and said second transporting member are self-propelled along the assembly line, wherein the transporting pitch to be established increases as the number of assembly man-hours required for the first workpiece increases;
• sending said first transporting member off from said starting end toward an assembly location of the assembly line;
• and
• sending said second transporting member off from said starting end, such that a distance between said first transporting member and said second transporting member becomes equal to the determined transporting pitch and remains equal thereto until said first transporting member arrives at the assembly location.