This valve controls hydraulic flow within the steering circuit of the header assembly. It mounts in the line between the steering cylinder and the return manifold, modulating flow to maintain consistent steering response under varying load. A worn or leaking valve causes sluggish steering and uneven header tracking. The manufacturer machines the sealing surfaces to match the original housing bore, preserving the cracking pressure the system requires for proper centering. When reinstalling, replace the O-ring on the valve body and tighten the retaining nut to the specified torque.