Abstract: A pressure medium-actuated control device of an automated step-by-step variable speed transmission. The device having a control valve for controlling an actively engaged disconnectable type clutch which is disposed along a power flow path between a motor and a transmission input shaft, and a self-retaining valve located in the pressure supply of the clutch control valve for a rotational speed-dependent emergency actuation of the disconnectable type clutch. An electrical switch-off actuator is connected to the self-retaining valve such that the valve piston, of the self-retaining valve, can be moved into an idle position to lock the pressure supply of the clutch control valve in a powered state of the switch-off actuator, and into an operating position determined by the applied control pressures in the power-off state of the switch-off actuator.

Abstract: The invention involves a control valve arrangement to activate at least one start-up clutch of a motor vehicle automatic transmission with at least one clutch control valve (3, 3?, 3?) across which a supply pressure (P_V1) can be led into a pressure chamber of an associated clutch activation device (4, 4?), with a pressure regulating valve (166), which is controlled by an electronic control device, and at least one control valve of the control valve arrangement is supplied with a pilot pressure (P_VST3), and with a self-maintaining hydraulic unit with whose help a hydraulic emergency operation can be maintained with a closed start-up clutch upon the failure of an electronic control device and thus the absence of a pilot pressure (P_VST3) in at least many operational situations.

Abstract: A control valve arrangement having a clutch regulation valve (3), which pressurizes a device to actuate the clutch, and a valve that produces a controlled pilot pressure (P_VST3). An electronic control unit (ECU) controls a valve to supply a control valve with the pressure (P_VST3). The arrangement further having a hydraulic system which, if the ECU fails and the pressure (P_VST3) ceases, the last shift condition of the clutch actuation device, prior to the ECU failure, can be maintained in an emergency. The arrangement includes a valve, which delivers an activation pressure (P_A), depending on an engine-speed-dependent control pressure (P_D), to an actuation valve (2), which then delivers the pressure (P_A) to the valve (3) to prevent the emergency function initiation despite a lack of pressure (P_VST3) and existance of the pressure (P_D) sufficiently high to initiate the emergency function.

Abstract: A device for controlling a hydraulically operable switching element (2) of an automatic transmission of a vehicle with a position valve mechanism (3) having a main switch piston (6) which is spring biased into a first switch position and a second switch position with a pilot pressure (P_MV) which is adjustable through an electrically operated actuator (5). An additional switch piston (7) and the main switch piston (6) are axially actuated in a valve housing (8). Depending on the position of the pistons (6, 7), faces (6A, 7A) of the respective pistons are either spaced apart or adjacent. The additional switch piston (7) is adjustable depending on a pilot pressure (p_K) of a switching element which engages a gear for forward drive.

Abstract: A device for the control of a hydraulically actuated clutch (1) of an automatic transmission of a motor vehicle having a slide-valve mechanism (3) is proposed, in which a valve piston (4) can move between a first working space (7) which can be pressurized via a control line (8) with a control pressure (p_MV) adjustable by means of an electrically operated actuator (9) and a restoring space (10) containing a restoring spring (11) that acts on the valve piston (4). The valve piston (4) is made with several piston sections (4A, 4B) that delimit a pressure space (12) which is connected via a line (13) to a clutch space (2) of the clutch (1) and which, depending on the position of the valve piston (4), has a connection to a pressure supply line (14) delivering a system pressure (p_sys) or to a pressure-relief line (15).

Abstract: A device for the control of a hydraulically actuated clutch (1) of an automatic transmission of a motor vehicle having a slide-valve mechanism (3) is proposed, in which a valve piston (4) can move between a first working space (7) which can be pressurized via a control line (8) with a control pressure (p_MV) adjustable by means of an electrically operated actuator (9) and a restoring space (10) containing a restoring spring (11) that acts on the valve piston (4). The valve piston (4) is made with several piston sections (4A, 4B) that delimit a pressure space (12) which is connected via a line (13) to a clutch space (2) of the clutch (1) and which, depending on the position of the valve piston (4), has a connection to a pressure supply line (14) delivering a system pressure (p_sys) or to a pressure-relief line (15).