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 conical pulley assembly with integrated torque sensor. A torque-dependent force is transmitted through a transmitting component to a sensing piston whose position determines the pressure in a sensing chamber. The transmitting member is connected to the movable disk, and is formed in such a way that it transmits the torque-dependent force to the sensing piston in a manner that is dependent on the position of an axially movable disk of the conical pulley.

Abstract: A compressor drive system for driving a compressor of an internal combustion engine contains a variable speed drive unit and a planetary gear set, the planetary gear set being connected to the internal combustion engine and the compressor in such a way that a first output shaft of the planetary gear set is connected to the compressor, a first drive shaft of the planetary gear set is connected to the internal combustion engine, and a second drive shaft of the planetary gear set is connected to the internal combustion engine through the variable speed drive unit.

Abstract: A hydraulic supply system for a motor vehicle includes an internal combustion engine, a pump driven by the internal combustion engine, and a hydraulically operated component that is driven by hydraulic fluid transported by the pump. An electric motor is provided to drive the pump when the internal combustion engine is not running.

Abstract: A hydraulic supply system for a hydraulically actuated automatic transmission, in particular for a belt-driven conical-pulley transmission. The system includes a primary pump driven by a primary drive system to provide pressure in a supply line connected to a regulating valve. The supply line is connected through a pilot valve to a control line in which a control valve is situated, with which the pressure that determines the setting of a transmission ratio adjusting valve is set. An auxiliary pump driven by an auxiliary drive system that is separate from the primary drive system includes an outlet line connected to the control line through a first valve that opens in the direction of the control line, and is connected to the supply line through a second valve that opens in the direction of the supply line.

Abstract: A hydraulic system for controlling a belt-driven conical-pulley transmission. A pump draws a working medium from a working medium tank or through a cooler return valve from a cooler return line. The cooler return valve is a minimum pressure valve that holds closed a connection between the cooler return line and a pump inlet line through the cooler return valve, as long as the pressure in the cooler return line remains below a specified minimum pressure. The cooler return valve also opens the connection between the cooler return line and the pump inlet line through the cooler return valve as soon as the specified minimum pressure in the cooler return line is exceeded.

Abstract: A clutch control device for controlling the operation of a hydraulically operated clutch with a flow control valve. The control device includes a volume flow regulating valve that enables both volume flow regulated filling and volume flow regulated emptying of a hydraulic clutch positioning element, to provide rapid and precise operation of the clutch.

Abstract: A method and apparatus for cooling a clutch of a motor vehicle by controlling a valve through which a coolant circuit is coupled with a pump circuit. The valve includes a control piston that is movable at least to actuate a connection between the coolant circuit and the pump circuit.

Abstract: A pressure medium supply unit for a hydraulic system of a motor vehicle that includes a clutch requiring a high hydraulic pressure and a low volumetric flow rate of hydraulic fluid for operation, and an automatic transmission requiring a low hydraulic pressure and a high volumetric flow rate of hydraulic fluid for operation. A single hydraulic pump is provided to supply hydraulic fluid to both the clutch and the transmission.

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.

Abstract: A hydraulic system for an automatic transmission operatively connected to an internal combustion engine that is operable in a start-stop mode. The hydraulic system includes a hydraulic energy source to supply the hydraulic system with hydraulic energy, the hydraulic energy source including at least one electrically driven hydraulic pump to supply the hydraulic system with hydraulic energy during a stopping phase of the internal combustion engine. To achieve a reduction in fuel consumption and CO2 emissions, provision is included to enable the electrically driven hydraulic pump to be switched on in addition to a mechanically driven hydraulic pump, as needed during an operating phase of the internal combustion engine.

Abstract: A volume flow regulating valve for a hydraulic system for controlling a belt-driven conical-pulley transmission. The valve includes a control piston with a pressure surface and an oppositely facing pressure return surface. A supply segment is associated with the pressure surface, and a cooler return segment is connectable with the supply segment by a control edge of the control piston. A pressure return segment is associated with the pressure return surface, and a pressurizing segment is situated between the cooler return segment and the pressure return segment.

Abstract: A hydraulic system for actuating a clutch of a vehicle, in particular a commercial vehicle, having a pressure reducing valve under system pressure for pressuring the clutch with an actuating pressure in normal operation, where at least one additional reserve valve assembly is provided for emergency operation. In addition, a hydraulic system is proposed for actuating a variator of a CVT transmission of a vehicle, in particular a commercial vehicle, having at least one pressure reducing valve for pressuring a first shifting chamber and a second shifting chamber of the pulleys with an adjusting pressure to set a transmission ratio in normal operation, where at least one selector valve is connected to the first shifting chamber and the second shifting chamber of the respective pulleys.

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 hydraulic system for controlling a belt-driven conical-pulley transmission of a motor vehicle, wherein the transmission has a variably adjustable transmission ratio. The hydraulic system includes a first valve arrangement to ensure a contact pressure in the belt-driven conical-pulley transmission, a second valve arrangement to control the transmission ratio of the belt-driven conical-pulley transmission, and a hydraulic energy source to supply the hydraulic system with hydraulic energy. In order to provide an improved hydraulic system, the system a third valve arrangement for controlling a forward clutch and a reverse clutch.

Abstract: A hydraulic system for controlling a belt-driven conical-pulley transmission of a motor vehicle having a variably adjustable transmission ratio, and having an electrical actuation system for overall control of the hydraulic system, and a hydraulic parking lock-release system to control a parking lock. In order to provide an improved hydraulic system, the parking lock includes a self-retention system in the event of an electrical power failure.

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 comprising a pump for feeding hydraulic fluid from an inlet side to an outlet side, wherein a pressure accumulator is disposed at the outlet side, wherein between the pump and the pressure accumulator a hydraulic control valve is disposed, which has at least two valve positions, wherein the outlet side of the pump is connected to the pressure accumulator in a first valve position, and separated from the pressure accumulator in a second valve position, wherein the outlet side of the pump is connected to the inlet side through the control valve in the second valve position.

Abstract: A hydraulic system for controlling a belt-driven conical-pulley transmission of a motor vehicle, wherein the transmission has a variably adjustable transmission ratio. The hydraulic system includes a first valve arrangement to control a contact pressure in the belt-driven conical-pulley transmission, a second valve arrangement to control the transmission ratio of the belt-driven conical-pulley transmission, and a hydraulic energy source to supply the hydraulic system with hydraulic energy. In order to provide an improved hydraulic system, the system includes a third valve arrangement for controlling a forward clutch and a reverse clutch.

Abstract: A hydraulic system for controlling a belt-driven conical-pulley transmission of a motor vehicle, wherein the transmission has a variably adjustable transmission ratio. The hydraulic system includes a first valve arrangement to control a contact pressure in the belt-driven conical-pulley transmission, a second valve arrangement to control the transmission ratio of the belt-driven conical-pulley transmission, and a hydraulic energy source to supply the hydraulic system with hydraulic energy. In order to provide an improved hydraulic system, the system includes a third valve arrangement for controlling a forward clutch and a reverse clutch, and for controlling a parking lock.