Pilot valve apparatus

In a pilot valve apparatus having a valve body with a first pair of outlet ports and a second pair of outlet ports, for outputting fluid from an output port selected from said first and second pairs of outlet ports by pivoting a lever in a corresponding direction;

• the improvement characterized in that said valve body has a inlet port and a pressure detecting port, and a pressure detecting directional control valve is provided between said pressure detecting port and said inlet port.
• said pressure detecting directional control valve being shiftable between a first position and a second position, said pressure detecting directional control valve in its first position connecting said pressure detecting port to said inlet port, said pressure detecting directional control valve in its second position disconnecting said pressure detecting port from said inlet port, said pressure detecting directional control valve being shifted between said first and second positions by pressure of fluid from said first pair of outlet ports of said valve body;
• wherein said pressure detecting directional control valve comprises a first spool and a second spool positioned in a pressure detecting directional control valve chamber to form first and second pressure receiving chambers, with said first pressure receiving chamber being in communication with one outlet port of said first pair of outlet ports, and with said second pressure receiving chamber being in communication with other outlet port of said first pair of outlet ports;
• wherein said pressure detecting directional control valve further comprises a spring which biases said first spool against said second spool to a first position of said first spool wherein said pressure detecting port is thereby disconnected from said inlet port, wherein said first pressure receiving chamber is located at a junction between said first and second spools, wherein said second pressure receiving chamber is located at the end of said second spool remote from said first spool, and wherein pressure in said first and second pressure receiving chambers tends to move said first spool against the bias of said spring to a second position of said first spool wherein said pressure detecting port is thereby connected to said inlet port.

In a pilot valve apparatus wherein a valve body has an inlet port, at least a first pair of outlet ports, and at least a first pair of valve spools, each valve spool of said first pair of valve spools being associated with a respective one of said first pair of outlet ports and being selectively operable by pivoting a lever in a selected direction of movement of the lever for outputting oil from the inlet port to one of the first pair of outlet ports by a stroke of the associated one of said first pair of valve spools within the valve body;

• the improvement characterized in that said valve body has a pressure detecting port, and a pressure detecting directional control valve is provided within said valve body between said pressure detecting port and said inlet port to connect said pressure detecting port to said inlet port in a connecting position of said pressure detecting directional control valve and to disconnect said pressure detecting port from said inlet port in a disconnecting position of said pressure detecting directional control valve;
• wherein said pressure detecting directional control valve comprises a first spool and a second spool positioned in a pressure detecting directional control valve chamber in said valve body to form first and second pressure receiving chambers, with said first pressure receiving chamber being between said first and second spools, with said second pressure receiving chamber being at the end of the said second spool which is remote from said first spool, said first pressure receiving chamber being in communication with one outlet port of said first pair of outlet ports, and with said second pressure receiving chamber always being in communication with the other outlet port of said first pair of outlet ports.