Patent ID: 6647721
Filing Date: 2003-11-18
Classification: B60T,E02F,F15B,Y10T

Abstract:
A swing damping valve for a backhoe, the backhoe having at least one swing cylinder having an extend and a retract port for swinging a backhoe boom in two directions about a substantially vertical axis, and a directional control valve coupled between a hydraulic tank and a hydraulic supply and configured to provide fluid to the extend and retract ports of the at least one swing cylinder through an extend port and a retract port line wherein the valve comprises:a valve body having a first port configured to be coupled to the extend port of the directional control valve, a second port configured to be coupled to the retract port of the directional control valve, a third port configured to be coupled to move the swing cylinder in a first of said two directions and a fourth port configured to be coupled to move the swing cylinder in a second of said two directions, wherein the valve body further defines a first fluid flow conduit configured to permit bidirectional flow between the first and third port, and a second conduit configured to permit bi-directional flow between the second and fourth ports, and wherein the valve body further defines a third conduit coupling the first and second conduits; and a movable cross-over valve element disposed in the valve body and in the flow path defined by the third conduit to selectively block flow through the third conduit in response to a difference in pressure between the first and second conduits.