Hydraulically actuated piston with an air bleed

Abstract

A torque transmitting mechanism has a hydraulically actuated piston that is slidably disposed in a cavity. An apply chamber, formed by the piston and cavity, is filled with hydraulic fluid when the torque transmitting mechanism is to be engaged. One or more gas permeable—liquid impermeable mats are secured in a passage between the chamber and a non-liquid area in a transmission. During initial engagement of the torque transmitting mechanism, any entrapped air is forced out of the chamber through the mat while the leakage of liquid is inhibited. In a rotating torque transmitting mechanism (clutch), the mats are installed near the innermost periphery of the chamber. In a stationary torque transmitting mechanism (brake) the mats are installed near the top outermost periphery of the chamber.

Dependencies are inferred from the claim text.