HYDRAULIC STROKING DEVICE, PLANETARY GEAR AUTOMATIC TRANSMISSION, AND CLUTCH APPARATUS

摘要

A hydraulic stroking device that performs stroking action by adjusting a pressure of hydraulic fluid in a fluid chamber is disclosed. The hydraulic device includes a hydraulic piston, a sealing member, and a variable sealing performance mechanism. The piston is provided in a fluid chamber, and receives the pressure of hydraulic fluid and is moved by the pressure. The sealing member seals between a circumferential surface of the piston and an inner surface of the fluid chamber. When the piston is not moving with the hydraulic fluid being pressurized, the variable sealing performance mechanism enhances the sealing performance of the sealing member compared to the sealing performance in a state when the piston is being moved.