Fluid under pressure, delivered along pipe 7, passes through throttle 2, located in the axial passage of valve spool 3, and is admitted into chamber A from where it passes to adjustable nozzle 4. The nozzle opening is covered by shutter 5, mounted on bell-crank lever 6. Lever 6 turns on a knife-edge support and is subject to the action of spring 7. Acting on the other arm of lever 6 is the operating member of a sensing element which deflects lever 6 upon a change in the parameter being regulated. When shutter 5 approaches nozzle 4, the pressure is raised in chamber A and membrane 8 shifts valve spool 3 to the left. At this, fluid under pressure is delivered through pipe 9 to the hydraulic system. When the pressure in chamber A drops, spring 10 shifts spool 3 to the right, connecting pipe 9 of the hydraulic system through pipe 11 to the tank.
$4224$CHP,Dr$