Drive transmission mechanism for biaxial extruder

A drive mechanism for a biaxial extruder having first and second output shafts connected to first and second screws, comprising:

• first and second output gears respectively fitted on the first and second output shafts such that said first and second output gears are mutually offset on axes of the first and second output shafts, wherein a distance between said first screw and said first output gear is shorter than a distance between said second screw and said second output gear;
• a first lower gear and a first upper gear respectively meshing with said first output gear, said first lower gear and said first upper gear being vertically spaced across the axis of the first output shaft;
• a second lower gear and a second upper gear respectively meshing with said second output gear, said second lower gear and said second upper gear being vertically spaced across the axis of the second output shaft;
• a common drive source;
• and
• a reduction gear train for quartering a drive force from the common drive source equally and distributing the quartered drive force to said first lower gear, said first upper gear, said second lower gear and said second upper gear, said reduction gear train comprising:
• a) an upper intermediate shaft comprising torsion bars and having an upper input gear and first and second upper distribution gears mounted thereon, said first and second upper distribution gears respectively meshing with said first and second upper gears,
• b) a lower intermediate shaft comprising torsion bars and having a lower input gear and first and second lower distribution gears mounted thereon, said first and second lower distribution gears, respectively meshing with said first and second lower gears, and
• c) a center shaft having a drive gear meshing with said upper and lower input gears,
• wherein a spacing of said first upper distribution gear from said upper input gear on said upper intermediate shaft is greater than a spacing of said second upper distribution gear from said upper input gear on said upper intermediate shaft, and
• wherein a spacing of said first lower distribution gear from said lower input gear on said lower intermediate shaft is equal to a spacing of said first upper distribution gear from said upper input gear on said upper intermediate shaft and is greater than a spacing of said second lower distribution gear from said lower input gear on said lower intermediate shaft.