on the valve spring member 29 the pressure to be limited by valve 25 is introduced e g from a timing chamber through axial passage 27 and ports 28 to the portions of spring member 29 which cover and seal the outlets of ports 28 as long as the pressure force on the exposed area of the valve spring member 29 is smaller than the ring deformation force the ports 28 remain closed when the pressure force exceeds the preset preload the ring is deformed further into a more elongated shape and the pressurized fluid starts escaping through the resultant clearance between the inner surface of the valve spring member 29 and the surface of circumferential wall 26b and then into a free space below the plunger or into a drain passage as the spring member becomes more elongated gap g closes thereby setting a limit to the amount of elongation i e valve lift when the fluid pressure drops back below the preload spring member 29 reseals the ports however since the contact area around the port outlets is relatively large a fuel film is trapped between the valve spring member 29 and the contact areas of circumferential wall 26b and produces a hydraulic damping along with that produced by fuel in gap g to minimize valve chatter importantly because the valve spring member 29 is loaded in bending instead of being stretched in a normal press or shrink fit a lower effective spring rate can be achieved the obtaining of a lower spring rate in turn.