A piston, in particular for a gear-change selector, including a piston body with a piston skirt and with a piston end face which can be pressurised with a working fluid. The piston includes a first sealing portion and a second sealing portion. The piston body and the first sealing portion have mutually complementary geometries so that they form a first vent channel. The first vent channel is arranged in a hydraulic series circuit with the second sealing portion. The second sealing portion prevents venting up to a first pressure and allows this above the first pressure. The invention furthermore concerns a gear-change selector and a gearshift for a vehicle.

Vehicles and related systems and methods are provided for round-robin air purging of disengaged clutches. One method involves obtaining a plurality of weighting factors associated with respective ones of a plurality of clutches of a vehicle transmission, obtaining an exhaustion time associated with each respective clutch, determining a respective priority metric associated with the each respective clutch based at least in part on the exhaustion time associated with the respective clutch and the respective weighting factor associated with the respective clutch, determining a highest priority clutch of the plurality of clutches based at least in part on the respective priority metrics associated with the respective clutches of the plurality of clutches, and operating one or more valves in accordance with a pulse command to pulse the highest priority clutch with a commanded pressure for a commanded period of time.

An automatic transmission has an oil pump driven by a travelling driving source. An air vent structure that expels air bubbles contained in automatic transmission fluid during pump operation has an air vent hole whose one end communicates with an outlet port of the oil pump and whose other end opens toward the oil pan. An air vent tube is connected to an opening end of the air vent hole. The air vent tube is extended up to a strainer lower side gap area located between a strainer and the oil pan, and a tube opening end of the air vent tube is placed in oil of the automatic transmission fluid.

Disclosed is a method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging the gears of the vehicle transmission, where, in a neutral gear an input (AN) and an output (AB) of the vehicle transmission are decoupled from one another, and where, in a driving gear the input (AN) and the output (AB) of the vehicle transmission are coupled to one another in order to propel the vehicle, by closing at least one shifting element (B). When the neutral gear is engaged, at least an actuation condition of a vehicle brake (11) and a transmission condition with elevated drag losses are detected, where, when the neutral gear is engaged, the shifting element (B) for the driving gear is vented if it is recognized that the vehicle brake (11) has been released and the transmission condition with elevated drag losses pertains.

Disclosed is a method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging the gears of the vehicle transmission, where, in a neutral gear an input (AN) and an output (AB) of the vehicle transmission are decoupled from one another, and where, in a driving gear the input (AN) and the output (AB) of the vehicle transmission are coupled to one another in order to propel the vehicle, by closing at least one shifting element (B). When the neutral gear is engaged, at least an actuation condition of a vehicle brake (11) and a transmission condition with elevated drag losses are detected, where, when the neutral gear is engaged, the shifting element (B) for the driving gear is vented if it is recognized that the vehicle brake (11) has been released and the transmission condition with elevated drag losses pertains.

A method is for testing a hydraulic system (1), having a pump (2) which, in a first direction of rotation (3), conveys fluid to a first consumer (4) for a volume flow function and, in a second direction of rotation (5), conveys fluid to at least one second consumer (6) for an actuation function. The method includes testing hydraulic readiness of the hydraulic system (1); drawing fluid into the hydraulic system (1); ventilating the hydraulic system (1). A hydraulic system (1) carries out such a method, having a pump (2) which can be driven in a first direction of rotation (3) for a volume flow function and can be driven in a second direction of rotation (5) for an actuation function.

A breather device that communicates an inside of a case with an outside of the case in a vertical direction includes a cylindrical body having a hollow portion that extends in the vertical direction, a stopper inserted in the hollow portion, and a blocking body that is located in a space defined by the stopper in the hollow portion, and blocks a communicating hole provided in a lower part of the cylindrical body as viewed in the vertical direction. The communicating hole ceases to be blocked when the pressure inside the case exceeds a first predetermined value, and the blocking body moves upward in the vertical direction in the space.

An automatic transmission assembly for mounting to a power-source includes a torque converter operatively connected to the power-source. The transmission assembly also includes a turbine shaft for receiving power-source torque from the torque converter. The transmission assembly additionally includes a torque transfer system, having a gear-train and a hydraulic pressure operated torque-transmitting device, for receiving the torque from the turbine shaft and selecting an input-to-output speed-ratio of the transmission. The transmission assembly also includes an output member for receiving torque from torque transfer system and outputting the torque to drive a load. The turbine shaft defines a first passage configured to supply hydraulic pressure to the torque-transmitting device and a second passage configured to vent to atmosphere. The turbine shaft additionally defines a third passage fluidly connecting the first passage to the second passage and thereby configured to bleed air from the torque-transmitting device.

An automobile vehicle transmission air vent system includes a first component of a vehicle transmission having a resilient material seal member retained in a cavity created in the first component. A second component of a metal material includes a vent groove facing toward the seal member. A clutch pack of the vehicle transmission is actuated by one of the first component or the second component being displaced into engagement with the clutch pack. The vent groove receives a portion of the seal member in a first displaced position of the displaced one of the first component or the second component defining an air and oil flow path through the vent groove between the first component and the second component. The seal member is positioned outside of the vent groove in a second displaced position of the displaced one of the first component or the second component.

A breather device that communicates an inside of a case with an outside of the case in a vertical direction includes a cylindrical body having a hollow portion that extends in the vertical direction, a stopper inserted in the hollow portion, and a blocking body that is located in a space defined by the stopper in the hollow portion, and blocks a communicating hole provided in a lower part of the cylindrical body as viewed in the vertical direction. The communicating hole ceases to be blocked when the pressure inside the case exceeds a first predetermined value, and the blocking body moves upward in the vertical direction in the space.