Stepless speed changing device

A stepless speed changing device having a stepless speed changing unit and a summarizer and converting its operational mode by a clutching motion in a synchronous speed condition to transmit input torque to an output shaft while changing a rotating speed, the device comprising:

• first and second gears fixedly and rotatably fitted over a torque input shaft, respectively, said second gear being selectively clutched to said input shaft by a first clutch to convert the operational mode into a third mode;
• third and fourth gears rotatably fitted over a driven shaft and meshing with said first and second gears respectively to form a pair of gear sets having different gear ratios, both said third and fourth gears being selectively clutched by a second clutch to convert the operational mode into a first mode;
• the stepless speed changing unit mounted to the input shaft and connected to the summarizer by power transmission means;
• the summarizer mounted to said driven shaft and constructed of an epicycloidal gear train, said gear train including:
• a planetary gear carrier fixed to said fourth gear and carrying a planetary gear;
• a sun gear fixedly fitted over the driven shaft and gearing into said planetary gear;
• a ring gear meshing with said planetary gear;
• and
• a fifth gear rotatably fitted over the driven shaft and fixed to said ring gear;
• a sixth gear rotatably fitted over said driven shaft, said sixth gear being selectively clutched by a third clutch to convert the operational mode into a second mode;
• and
• seventh, eight and ninth gears fixedly fitted over an intermediate shaft, said seventh and eight gears meshing with said fifth and sixth gears of the driven shaft, respectively, while said ninth gear meshing with a tenth gear of said output shaft.