An oil supply system of an automatic transmission or an automated manual transmission in a power train has an oil pan and a pressure line for supplying elements of the transmission with pressurized oil. A pumping device pumps oil from the oil pan into the pressure line at a supply pressure P.sub.0. A hydrodynamic converter, being a starting element, forms a subsection of the pressure line. A hydrodynamic retarder is disposed in a retarder oil circuit. At least a first switching valve, a second switching valve and a heat exchanger, wherein the heat exchanger is selectively switchable, by way of the switching valves, as a subsection into the pressure line or the retarder oil circuit. A temperature sensor is provided following the pumping device in the direction of flow in order to detect the oil temperature in the pressure line.

Disclosed is a hydraulic damper comprising a rotor (1), a stator (2) and a drive shaft (3) for driving the rotor (1), the rotor (1) and the stator (2) being mutually forming a working chamber (4) in which liquid medium is accommodated, wherein the stator (2) is provided in turn with an outlet (21), a nozzle (22), an exhaust channel (23), an ejector channel (24) and an inlet (25); the outlet (21), the exhaust channel (23) and the inlet (25) are communicated with the working chamber (4) respectively; the ejector channel (24) is in communication with the outlet (21), the exhaust channel (23) and the inlet (25) respectively; the nozzle (22) is arranged at the junction where the outlet (21) is connected with the exhaust channel (23) and the ejector channel (24); the nozzle (22) is extended along the lead-out direction of the outlet (21) to the junction where the exhaust channel (23) is connected with the ejector channel (24), and the channel width of the nozzle (22) at the extension is smaller than that of the outlet (21) and that of the ejector channel (24) respectively. With the Bernoulli's principle, hydraulic damper proposed in the present application can effectively avoid the loss of the liquid medium in the working chamber (4).

Disclosed is a hydraulic damper comprising a rotor (1), a stator (2) and a drive shaft (3) for driving the rotor (1), the rotor (1) and the stator (2) being mutually forming a working chamber (4) in which liquid medium is accommodated, wherein the stator (2) is provided in turn with an outlet (21), a nozzle (22), an exhaust channel (23), an ejector channel (24) and an inlet (25); the outlet (21), the exhaust channel (23) and the inlet (25) are communicated with the working chamber (4) respectively; the ejector channel (24) is in communication with the outlet (21), the exhaust channel (23) and the inlet (25) respectively; the nozzle (22) is arranged at the junction where the outlet (21) is connected with the exhaust channel (23) and the ejector channel (24); the nozzle (22) is extended along the lead-out direction of the outlet (21) to the junction where the exhaust channel (23) is connected with the ejector channel (24), and the channel width of the nozzle (22) at the extension is smaller than that of the outlet (21) and that of the ejector channel (24) respectively. With the Bernoulli's principle, hydraulic damper proposed in the present application can effectively avoid the loss of the liquid medium in the working chamber (4).

A rotational speed control device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor may be movable axially on the shaft depending on the rotating speed of the shaft. The rotor is biased in a low torque direction. A braking torque between the rotor and the housing and/or between the rotor and a drive control ring is varied according to an axial position of the rotor on the shaft. The device may incorporate bypass channels to control a circulating pressure of the viscous fluid.

A rotational speed control device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor may be movable axially on the shaft depending on the rotating speed of the shaft. The rotor is biased in a low torque direction. A braking torque between the rotor and the housing and/or between the rotor and a drive control ring is varied according to an axial position of the rotor on the shaft. The device may incorporate bypass channels to control a circulating pressure of the viscous fluid.

An electrical machine is presented. The electrical machine comprises a rotor, a stator, a housing and a first and a second fluid chamber in fluid communication via at least one fluid passage of the rotor. The rotor upon rotation is adapted to provide a difference in pressure between the first fluid chamber and the second fluid chamber by transfer of fluid there between, whereby a braking torque is exerted on the rotor.

An electrical machine is presented. The electrical machine comprises a rotor, a stator, a housing and a first and a second fluid chamber in fluid communication via at least one fluid passage of the rotor. The rotor upon rotation is adapted to provide a difference in pressure between the first fluid chamber and the second fluid chamber by transfer of fluid there between, whereby a braking torque is exerted on the rotor.

A hydrodynamic machine for producing a braking torque, the hydrodynamic machine comprising: a toroidal working chamber including a first bladed wheel and a second bladed wheel arranged concentrically with the first bladed wheel; and a hydraulic system including an open loop and closed loop control unit, a working medium accumulator, a line system, a pump operable to produce a volume flow circulation of a working medium through the line system and the toroidal working chamber, a heat exchanger, and a pressure control valve operable to control or adjust the baking performance or the braking torque.

A hydrodynamic machine for producing a braking torque, the hydrodynamic machine comprising: a toroidal working chamber including a first bladed wheel and a second bladed wheel arranged concentrically with the first bladed wheel; and a hydraulic system including an open loop and closed loop control unit, a working medium accumulator, a line system, a pump operable to produce a volume flow circulation of a working medium through the line system and the toroidal working chamber, a heat exchanger, and a pressure control valve operable to control or adjust the baking performance or the braking torque.

A hydrodynamic retarder device for installation in a driveline to a vehicle, wherein the retarder device comprises: a blade-equipped stator which, together with a blade-equipped rotor, forms a blade system with a workspace for receipt of an aqueous working medium, and a retarder circuit connected to the workspace to control the inflow of a working medium to the workspace, wherein the retarder circuit is installed to be connected to the vehicle's ordinary cooling water circuit. The retarder circuit comprises valve elements to shut off the flow of working medium to the workspace, and a negative pressure generator is connected in the retarder circuit, which is installed to reduce the pressure in the workspace to or below the vapor pressure for the working medium, so that the workspace is thus evacuated of the liquid working medium. The invention also pertains to a method and a vehicle.