Patent ID: 8875863
Filing Date: 2014-11-04
Classification: F16D

Abstract:
1. A multi-disc frictional engagement mechanism for coupling a first member and a second member which are coaxially arranged, comprising: a plurality of first friction plates mounted on the first member slidably in an axial direction; a plurality of second friction plates mounted on the second member slidably in the axial direction, the plurality of first friction plates and the plurality of second friction plates being alternately arranged; a hydraulic piston arranged displaceably in a direction perpendicular to the pluralities of the first and second friction plates and including a radially extending pressure receiving portion; a piston oil chamber configured to cause a hydraulic pressure to act on the pressure receiving portion; an elastic member configured to come into contact with the pressure receiving portion from a side opposite to the piston oil chamber so as to bias the hydraulic piston toward the pluralities of the first and second friction plates; and a lock mechanism comprising a holding member and an engaging member, the lock mechanism being configured to restrict a movement of the hydraulic piston in a coupling direction toward the pluralities of the first and second friction plates in a state in which the hydraulic pressure is supplied to the piston oil chamber, the elastic member is compressed by the pressure receiving portion, and the pluralities of the first and second friction plates are not coupled, wherein the lock mechanism is locked when the hydraulic pressure of the piston oil chamber acts on the lock mechanism, and wherein the hydraulic piston is configured such that the restriction of the movement in the coupling direction by the lock mechanism is removed in a state in which the hydraulic pressure acts on a piston portion from the side opposite to the piston oil chamber and the holding member is separated from the engaging member.