To provide a power transmission for a four-wheel drive vehicle with a hydraulic coupling device wherein a check valve for preventing the occurrence of cavitation in a vane pump is reasonably arranged for requiring a shorter oil path and lower cost.
A suction port 43, a discharge port 44 and a cavitation preventing check valve 53 are collectively provided on one side face of one side plate 32 of a pair of side plates 30, 32 holding a cam ring 31 therebetween, thereby requiring the shorter oil path for connecting theses and lower cost. Because of no use of a check valve for the other side plate 30, the need for the side plate 30 is eliminated. In this case, a rotor 35 is supported at its side face on the side of the side plate 30 directly on the inner face of a pump casing 24.
MABUCHI TORU
MIYATA KAZUNORI
KUROKAWA TAKUYA
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