Abstract: The invention relates to a hydrodynamic machine, in particular a retarder, having an external working medium circuit, comprising: a bladed primary wheel and a bladed secondary wheel which together form a toroidal working chamber which can be filled with working medium from the external working medium circuit, which is fed back into the external working medium circuit; an annular channel disposed outside the working chamber, which is connected in a working-medium conducting manner to the working chamber via outlet holes in the primary wheel or secondary wheel, and is in flow-conducting communication with the external working medium circuit in order to collect working medium leaving the working chamber through the outlet holes and supply this to the external working medium circuit.

Abstract: The invention relates to a hydrodynamic machine, in particular a retarder, having an external working medium circuit, comprising: a bladed primary wheel and a bladed secondary wheel which together form a toroidal working chamber which can be filled with working medium from the external working medium circuit, which is fed back into the external working medium circuit; an annular channel disposed outside the working chamber, which is connected in a working-medium conducting manner to the working chamber via outlet holes in the primary wheel or secondary wheel, and is in flow-conducting communication with the external working medium circuit in order to collect working medium leaving the working chamber through the outlet holes and supply this to the external working medium circuit.

Abstract: The invention concerns a combined relief and positive surge protection device for operating fluid containers that can be put under pressure in operating fluid supply systems of hydrodynamic machines with a housing; with an inlet chamber that can be coupled to the inner space of the operating fluid container and an outlet chamber that can be coupled to a relief space; with a relief valve that comprises a valve component that is supported in the housing in such a way that it can be displaced, and a valve seat that is arranged stationary in the housing, whereby the valve seat is arranged in such a way that it, in cooperation with the valve component, blocks the connection between the inlet chamber and the outlet chamber; with an actuation mechanism that is assigned to the valve component; with a positive surge protection device comprising a positive surge plate that can be guided outside the housing on a guidance element that is connected to the valve component, whereby the guidance element contains, on its e

Abstract: A method and apparatus for accelerated emptying of an operating substance from the working chamber of a hydrodynamic retarder is provided which uses a gaseous medium that is introduced into the working chamber to induce volume displacement.