Check-relief valve for a hydraulic circuit

Abstract

A check-relief valve for use in a hydraulic circuit comprises a channel through a valve body which is divided by a central annular restriction into two portions. On each side of the restrictor is provided a valve seat which cooperates with a spherical ball to close off flow in a direction toward the restriction. At the outer end of each portion of the channel is provided a perforated plate which prevents the ball from restricting flow when the ball is forced against the plate. Either the ball or the restrictor is formed of a resilient deformable material which can be deformed when the pressure in the fluid exceeds a predetermined maximum in which case the ball is forced through the restriction to the opposite portion of the channel. The check valve is used in a system of a swather for moving one of the draper assemblies longitudinally of the frame of the swather and simultaneously reversing the direction of rotation of the drive to the draper. A check valve restricts the fluid flow to the drive motor for the rotation of the draper so that all of the fluid is available to move the draper and its support longitudinally of the frame until the draper reaches end stops whereupon the check valve releases by the deformation of the valve member to allow fluid to continue to flow through the drive motor to the draper rotation.