A simple spool valve combined with load sensing principles is used for precision flow control on demand. This type of valve, even though it has been in use for about ten years, received new attention during the energy crunch of 1974 and the subsequent interest in load sensing systems The load sensing flow control has been used on many applications and especially for power steering circuits where priority flow is needed. The valve functions in all systems: open center, closed center, and load sensing. It provides flow and pressure to a controlled circuit on demand (only as much as needed).This paper describes the function and some applications of the valve and includes system considerations. Generally, a fluid linked power steering system is used for illustration but the same principles can apply to any circuit using a special four way valve.