Frictional engagement element with stationary servo cylinder for planetary transmission

摘要

A stationary cylinder type of power transmission apparatus includes two rotational members 53 and 54, a thrust member 33 and a reactional member 56. A frictional engagement element 50 is disposed between and linked to the two rotational members 53 and 54 such that the frictional engagement element 50 freely transmits a rotational force to an outer periphery of one of the rotational members 53 and to an inner periphery of the other rotational member 54. The frictional engagement element 50 is engageable by and disposed between the thrust member 33 and the reactional member 56 in the axial direction. A bearing 32 is disposed interior to the frictional engagement element 50 in the radial direction, such that the thrust member 33 extends in the radial direction from the bearing 32 and along the frictional engagement element 50. A hydraulic servo 3 applies a force in the axial direction to the thrust member 33 via the bearing 32, such that the thrust member 33 transmits the force to the frictional engagement element 50, thereby engaging the frictional engagement element 50 with the thrust member 33 and the reactional member 56. An expulsion port 33A is also provided. A space S is created when the frictional engagement element 50 is engaged with the thrust member 33 and the reactional member 56. The expulsion port 33A is contiguous with an exterior side of the space S. Oil is supplied to the space S from an interior side of the frictional engagement element 50. The expulsion port 33A expels oil from the exterior side of the space S to outside of the space S.