Transmission vibration viscous damper

Claim 1

A manual transmission comprising an input shaft adapted to be clutched to the crankshaft of an internal combustion engine, said input shaft having an input gear integral therewith; said input gear formed with peripheral teeth and having a concentric axial bore formed as an integral part of said input shaft; a transmission output shaft supported at its forward end by journal means located in said axial bore, said output shaft having a speed gear formed with peripheral teeth journalled thereon, a countershaft having an axis of rotation parallel with the axis of rotation of said output shaft, the improvement wherein said countershaft having a viscous fluid damper coupling supported thereon, said coupling comprising a first driven gear journalled on said countershaft, said first driven gear having peripheral teeth in constant meshed engagement with said input gear peripheral teeth, a second driven gear fixed on said countershaft for rotation therewith, said second driven gear having peripheral teeth in constant meshed engagement with said speed gear peripheral teeth, a diametrical through bore extending through said countershaft intermediate said first and second driven gears, each said first and second driven gears formed with a set of longitudinally extending mirror image axial teeth arranged concentrically about said axis of rotation, said sets of axial teeth being sized to mesh in a loose fitting manner defining predetermined interconnected clearance spaces between said sets of axial teeth, said spaces being in communication with said through-bore and providing limited freedom of rotary movement of said first driven gear relative to said countershaft and said second driven gear, a hollow sleeve concentrically surrounding said sets of axial teeth, means sealing said sleeve to associated portions of said driven gears while allowing relative rotary movement between said sleeve and said first driven gear, means sealing said first driven gear to said countershaft whereby said sleeve and said first and second driven gears providing a sealed viscous fluid chamber comprising said through-bore and said interconnected spaces between said loosely mating axial teeth, clutch means for selectively connecting said speed gear in driving engagement with said output shaft, wherein upon said clutch means connecting said speed gear in driving engagement with said output shaft, the viscous fluid in said chamber providing a dampening medium substantially obviating the transfer of torsional vibrations from said input shaft to said countershaft and thus to said output shaft speed gear.