Patent ID: 6422804
Filing Date: 2002-07-23
Classification: E02F

Abstract:
A backhoe comprising:a supporting frame; a swing frame pivotally mounted to the supporting frame about a vertical pivot; a boom pivotally mounted to the swing frame; a dipperstick pivotally mounted to the boom; a work implement pivotally mounted to the dipperstick; a hydraulic swing cylinder extends between the supporting frame and the swing frame for pivoting the swing frame about the vertical pivot; a hydraulic circuit is hydraulically coupled to the hydraulic swing cylinder and comprises a source of pressurized hydraulic fluid, pressurized hydraulic fluid from the source of pressurized hydraulic fluid is directed through a first supply line to a swing control valve, from the swing control valve pressurized hydraulic fluid and exhausted hydraulic fluid is directed to and from the hydraulic cylinder through a work line, exhausted hydraulic fluid is directed by the swing control valve to the source of pressurized hydraulic fluid through an exhaust line having a back pressure check valve set at a first pressure level, an anti-cavitation valve is hydraulically positioned between the exhaust line and the work line, a second supply line extends between the first supply line and the exhaust line, a pressure reducing valve is hydraulically positioned in the second supply line and is set at a second pressure level, whereby the second pressure level is less than the first pressure level.