Patent ID: 8485212

Claim:
A volume flow regulating valve for a hydraulic system for controlling a belt-driven conical-pulley transmission, said valve comprising: a solid control piston slidably carried within a cylindrical bore, the control piston having a first pressure surface including a first control edge, and a second, pressure return surface axially spaced from and facing in a direction opposite to the first pressure surface, and including a pair of axially spaced annular grooves inwardly of the first pressure surface and the second, pressure return surface and defining respective fluid-receiving chambers for interconnecting valve segments; a supply segment in fluid communication with the first pressure surface; a cooler return segment in fluid communication with the supply segment upon movement of the first control edge of the control piston away from the supply segment and to the cooler return segment; a pressure return segment in fluid communication with the second, pressure return surface; and a pressurizing segment situated between the cooler return segment and the pressure return segment and in fluid communication with the supply segment through a conduit that is external of the cylindrical bore, wherein pressure within the pressurizing segment operates to prevent leakage flow from the pressure return segment to the pressurizing segment between the cylindrical bore and the control piston as increased wear occurs between the control piston and the cylindrical bore, thereby preventing a drop in pressure acting against the second, pressure return surface of the control piston.