a jam - proof , high pressure , check - valved input fitting comprising a travel limiting cage for controlling its internal valve spring system to prevent spring bending and cylinderization . a terminal engageably by a high pressure grease source leads to an internal tubular flow passageway comprising axially aligned inlets and outlets separated by a valve seat . a ball valve which contacts the valve seat to control fluid flow is biased by a spring coaxially seated within the upwardly projecting castellated end of the cage . the cage includes symmetrical , radially spaced apart legs and a plurality of relief orifices in the form of radially spaced apart slots defined between adjacent feet . the relief orifices establish fluid flow communication between the outside of the cage and its interior . when compressed downwardly against yieldable spring pressure , the ball is stopped by the cage before the spring can cylinderize . even when the ball valve is compressed against the cage by several thousand pounds of pressurem a blocking seal against the cage cannot be formed by the ball , since the relief slots provide an effective bypass .