Pilot-Operated Spool Valve

A pilot-operated spool valve comprising:

• a body defining:
• a bore;
• a supply port in fluid communication with the bore;
• and
• a load port in fluid communication with the bore;
• a spool disposed in the longitudinal bore;
• the spool and the body cooperating to define a command chamber at a first end of the spool, which command chamber is adapted to receive fluid at a command pressure supplied to the body,
• the spool being movable in the bore to control fluid communication between the supply port and the load port;
• and
• a pressure space defined in at least one of the body and the spool between the command chamber and both of the supply port and the load port in all operative positions of the spool, the pressure space being supplied with pressurized fluid such that leakage from the command chamber is minimized or eliminated.

A spool valve comprising:

• a body defining:
• a longitudinal bore;
• a supply port in fluid communication with the longitudinal bore and adapted to contain fluid at a supply pressure;
• and
• a load port in fluid communication with the longitudinal bore and adapted to contain fluid at a load pressure;
• a spool disposed in the longitudinal bore;
• the spool and the body cooperating to define a command chamber at a first end of the spool, which command chamber is adapted to receive fluid at a command pressure supplied to the body,
• the spool being movable between a first position permitting fluid communication between the supply port and the load port and a second position preventing fluid communication between the supply port and the load port;
• and
• a pressure space supplied with fluid at load pressure and disposed such that leakage from the command chamber is minimized or eliminated.