Multiple disc clutch apparatus

A driving apparatus for a four-wheel drive vehicle comprising:

• a driving gear meshing with an output gear of a transmission;
• a center differential disposed on the same axial line as said driving gear, for distributing power transmitted to said driving gear through said output gear to a driving system on the front wheel side and to a driving system on the rear wheel side;
• a front differential disposed on the same axial line as said center differential and connected to said center differential to transmit power to said driving system on the front wheel side, said front differential having a front differential case connected operatively to said center differential;
• a fixed casing for supporting rotatably said front differential case;
• a first hydraulic chamber formed in said fixed casing;
• a clutch piston disposed in said first hydraulic chamber and capable of pressing said front differential case by the action of the oil pressure generated in said first hydraulic chamber;
• a gear of said driving system on the rear wheel side, disposed on the same axial line as said center differential and connected operatively to said center differential;
• a multiple disc clutch disposed on the same axial line as said center differential and between said driving system on the front wheel side and said differential movements of the front and rear wheels, and brought into an operative state by the press operation of said front differential case;
• bearings disposed between said clutch piston and said front differential case and permitting them to rotate relatively;
• and
• hydraulic pressure generation means for letting a hydraulic pressure act on said clutch piston disposed in said first hydraulic chamber.