Patent ID: 8887886

Claim:
A power transmission device comprising left and right clutches including: left and right output shafts supported on a housing, the left and right output shafts being coaxial and rotatable relative to each other; an input shaft disposed on an outer periphery of one of the left and right output shafts in such a way as to be rotatable relative thereto; a clutch outer coupled to the input shaft; left and right clutch inners coupled to the left and right output shafts, respectively; a plurality of left frictional engagement members disposed between the clutch outer and the left clutch inner; a plurality of right frictional engagement members ( 62 ) disposed between the clutch outer and the right clutch inner; a left clutch piston configured to press the left frictional engagement members toward the right frictional engagement members; and a right clutch piston configured to press the right frictional engagement members toward the left frictional engagement members, wherein the clutch outer includes a boss portion positioned in an axial direction between the left and right clutch inners through a thrust bearing, left and right disk portions branching in two ways from the boss portion so as to support pressures of the left and right clutch pistons transmitted through the left and right frictional engagement members, respectively, and left and right drum portions extending in the axial direction from the left and right disk portions so as to guide outer peripheral portions of the left and right frictional engagement members, respectively, and a gap is formed between the left and right disk portions, radially outside of the boss portion.