Relief valves for hydrostatic drive systems

Abstract

The invention relates to a relief valve (15) for a hydrostatic drive system, which actuates a control pressure connection (ST) and a load pressure connection (LS), wherein the relief valve has a function position and an unloading position. The relief valve is designed as a double pressure limiting valve (20) in the form of a seat valve with a first valve seat body (21) for actuating the valve seat (26) of the load pressure connection and a valve for the control pressure connection The second valve seat body (22) operated by the seat (24). A control surface (30) acted upon by the load pressure present in the load pressure connection is formed on the first valve seat body, which loads the first valve seat body into the unloading position, in which the load pressure connection is directed toward the The box connector (T) is unloaded. A control surface (31) acted upon by the control pressure present in the control pressure connection is formed on the second valve seat body, which acts to load the second valve seat body into the unloading position, in which the control pressure connection is directed towards the Box connector unloaded.

Description

technical field [0001] The invention relates to a release valve for a hydrostatic drive system, which actuates a control pressure connection and a load pressure connection, wherein the release valve has a functional position and an unloading position. Background technique [0002] Such release valves are used as working hydraulics in load-sensing controlled drive systems of working machines such as land conveyors, construction machines, forestry machines, agricultural machines or municipal machines. The release valve is used to release the function of the control directional valve that controls the consumer of the working hydraulics and is also provided to prevent the consumer from operating and thus avoid danger in the event of a disturbance, malfunction or failure of the drive system operating status. [0003] A release valve of this type is known from DE 103 08 910 B4. To release the function of the control directional valve that controls the consumer of the working hyd...

AI Technical Summary

Problems solved by technology

The drop of the maximum system pressure due to the leakage of the load pressure on the relief valve results in: less force exists on the consumer and the efficiency of the working hydraulics of the working machine is reduced

[0006] A further disadvantage of the relief valve known from DE 103 08 910 B4 is that, in the functional position, when the spool is clamped, although the control pressure used to operate the pilot valve for operating the control directional valve can be reduced by the safety function reduced to the vessel, however the load pressure and thus the delivery pressure provided by the pump remains present

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