Abstract: A hydraulic system including a multi-flow hydraulic pressure supply unit, especially a dual-flow hydraulic pressure supply unit, such as a pump, by which a volumetric flow of pressurized fluid is supplied to a hydraulic-fluid-operated device. A valve arrangement is provided either for switching between the individual pump flows or for interconnecting the individual pump flows.

Abstract: A belt-driven conical-pulley transmission contained in the power train of a motor vehicle and having two conical disk pairs encircled by an endless torque-transmitting element. A hydraulic system is provided for pressing the conical surfaces of the conical disks against the endless torque-transmitting means and for opposite adjustment of the spacing between the conical disks for an adjustment of the transmission ratio. The hydraulic system includes a pump driven by an internal combustion engine that propels the vehicle, and the system includes an auxiliary oil source with which a predetermined minimum pressure is maintained in the hydraulic system when the internal combustion engine is shut off.

Abstract: A hydraulic system for actuating a clutch and/or a variable speed drive unit of a belt-driven conical-pulley transmission of a vehicle, such as a commercial vehicle, and having a variable transmission ratio and a torque sensor. The hydraulic system includes at least one hydraulic energy source. A selector and check valve is provided for supplying additional components besides the torque sensor and is connected between the hydraulic energy source, the additional components, and the torque sensor in such a way that the torque sensor includes priority in being supplied with hydraulic medium.

Abstract: The invention relates to a method and a device in the form of a hydraulic unit for triggering at least one clutch (5, 6) in a hydraulic circuit for an axle transmission of a vehicle. Said method and device make it possible to simply and very quickly make available an adequate amount of working fluid at the required pressure to at least one clutch according to the driving situation in order to close said clutch.

Abstract: A hydraulic system including a multi-flow hydraulic pressure supply unit, especially a dual-flow hydraulic pressure supply unit, such as a pump, by which a volumetric flow of pressurized fluid is supplied to a hydraulic-fluid-operated device. A valve arrangement is provided either for switching between the individual pump flows or for interconnecting the individual pump flows.

Abstract: A valve for controlling a clutch in a motor vehicle transmission. The valve includes a control spool that is movably received in a bore of a valve housing to control hydraulic flow to and from control channels in the housing and that open into the bore. The control spool is provided with a coating that includes at least one metal of the eighth sub-group and with a non-metal of the fifth main group of the periodic table.

Abstract: A pressure limiting valve having a spool with raised spool lands. The spool is slidably received in a spool bore having inflow and outflow grooves that form control edges. The valve has two control edges, and a hydraulic resistance is connected in series with one of the control edges. Increasing static pressure losses at the control edges during flow, so-called flow forces, can be offset by an increasing back pressure on the valve spool, which is produced by the hydraulic resistance.

Abstract: A hydraulic system having at least one hydraulic valve for actuating a component, wherein a control pressure acting on the hydraulic valve can be activated through a supply pressure of a pilot circuit having at least one actuator. At least one pressure reduction apparatus is connected in series with the actuator.

Abstract: A solenoid valve device, in particular a hydraulic valve device, has a solenoid element which is movable from a non-energized retracted state into an energized extended state, the working stroke of the solenoid element from its retracted state into its extended state including a constant magnetic force working stroke and an idle stroke in which the magnetic force is not constant, but decreases over the stroke.

Abstract: The invention relates to a hydraulic system comprising a multi-flow, especially dual-flow, hydraulic pressure supply unit, such as a pump, by which means a volume flow is supplied to a consumer. The invention is characterised in that a valve arrangement is provided for switching between the individual pump flows and/or for interconnecting the individual pump flows.

Abstract: A method for regulating or controlling the transmission ratio of an automatic power-branched transmission. Power is transmitted through a shaft driven by an engine, a variable speed drive, a gear transmission, a driven shaft, and at least two control clutches. The variable speed drive and the gear transmission are connected to each other in such a way that the regulating range of the variable speed drive is traversed in one direction within a first range of transmission ratios, and is traversed in the opposite direction within a second range of transmission ratios during traversing of the entire range of transmission ratios. The shifting strategies result in reduced wear of the endless belt device and allow for comfortable changing between the transmission ratio ranges.