Two-wheeled vehicle with hydraulic transmission

A two-wheeled vehicle comprising:

• a driving system having an input portion and an output portion;
• a variable displacement fluid pump provided at said input portion of the driving system, said variable displacement fluid pump being a radial plunger pump whose plungers are driven by a cam assembly, an eccentricity of said cam assembly being adjustable, said cam assembly comprising:
• an inner eccentric cam substantially in the shape of a cylinder eccentrically fixed to a center shaft and an outer eccentric cam substantially in the shape of a cylinder snuggly, rotatably and eccentrically fitted on the inner eccentric cam;
• said plunger pump comprising:
• eccentricity control means for changing the eccentricity of the eccentric cam assembly, said eccentricity control means comprising:
• an inner internal gear integral with said inner eccentric cam and having a center coincident with said center shaft;
• an outer internal gear rotatable together with said outer eccentric cam and having the same number of teeth and the same pitch diameter as those of said inner internal gear and located side-by-side, concentric to, and rotatable relative to said inner internal gear;
• a center gear rotatable on said center shaft;
• a fixed gear rotatable on a fixed member and meshing with said center gear and one of said internal gears;
• and
• a rocking gear rotatable on a free end of a rocking arm which is rotatably supported by said center shaft and meshes with said center gear and the other of said internal gears, thereby adjusting the eccentricity of said eccentric cam assembly in a stepless manner by rocking said rocking arm;
• and
• a fixed displacement fluid motor provided at said output portion of the driving system, said fluid pump and motor being connected through hydraulic passages, thereby driving the vehicle.