Sequence valve

A sequence valve for providing a fluid pressure control signal to a source of fluid flow comprising:

• a supply port for receiving output flow from said source of fluid flow;
• a tank port for returning fluid to said source of fluid flow;
• a load port for receiving a load signal generated by a load powered by said source of fluid flow;
• a control port for communicating said fluid pressure control signal to said source of fluid flow;
• and
• first and second fluid valves;
• said first fluid valve including cooperating valve surfaces disposed between said supply port and said control port to control fluid communication therebetween;
• said second fluid valve including other cooperating valve surfaces disposed between said tank port and said control port to control fluid communication therebetween.

A valve comprising:

• a housing;
• a passage in said housing;
• a load port and a supply port and a control port and a tank port each communicating with said passage;
• a piston movable in said passage and carrying a valve surface that opens and closes fluid communication between said supply port and said control port, said piston having a surface exposed to fluid pressure in said load port and a surface exposed to fluid pressure in said control port;
• a spool movable in said passage and carrying a valve surface that opens and closes fluid communication between said tank port and said control port, said spool having a surface exposed to fluid pressure in said control port and a surface engageable by said piston, and
• a spring acting against spool and biasing said spool in a direction opposite the direction of force applied by said fluid pressure in said control port acting against said surface of said spool exposed to said fluid pressure in said control port.

A hydraulic circuit comprising:

• a pressure responsive fluid flow source;
• a load;
• a sequence valve;
• said pressure responsive fluid flow source including a fluid flow outlet, a fluid flow inlet, and a pressure responsive device that increases and decreases fluid flow from said outlet;
• said load being in fluid communication with said fluid flow outlet;
• said sequence valve including:
• a load port in fluid communication with said load;
• a supply port in fluid communication with said fluid flow outlet,
• a tank port in fluid communication with said inlet,
• a control port in fluid communication with said pressure responsive device,
• a first valve disposed between said supply port and said control port,
• a second valve disposed between said tank port and said control port,
• said first valve including a valve surface operably connected to a first valve actuator surface, and said first valve actuator surface being in fluid communication with said load port.