Patent ID: 8602940

Claim:
A driving force transmission device comprising: a driving source; a clutch unit including a clutch coupled to the driving source and being capable of connecting or disconnecting transmission of driving force from the driving source, and a hydraulic cylinder configured to hydraulically control the engaging and disengaging of the clutch; a transmission unit coupled to the clutch unit, and including a transmission housing, a transmission mechanism built in the transmission housing, and a hydraulic source configured to generate a hydraulic pressure to required portions; a cylinder housing provided in the clutch unit and having a first hydraulic passage to the hydraulic cylinder; and a hydraulic part provided in the transmission unit and having a second hydraulic passage configured to be brought into communication with the first hydraulic passage in the cylinder housing by coupling the clutch unit thereto, wherein the cylinder housing is a stationary member including a cylinder oil chamber that is an oil chamber of the hydraulic cylinder, the cylinder oil chamber and the first hydraulic passage communicate with each other in the cylinder housing, and the cylinder housing and the hydraulic part are brought into close contact with each other to bring the first hydraulic passage and the second hydraulic passage into communication with each other.