Wide angle controller with dual function check valves

A controller operable to control the flow of fluid from a source of pressurized fluid to a fluid pressure operated device;

• said controller being of the type comprising housing means defining an inlet port for connection to the source of fluid, a return port for connection to a reservoir, and first and second control fluid ports for connection to the fluid pressure operated device;
• valve means disposed in said housing means and having a neutral position (FIG. 6), and first (FIG. 7) and second (FIG. 8) operating positions, corresponding to left and right turn conditions, respectively, and cooperating with said housing means to define a first main fluid path from said inlet port to said first control fluid port when said valve means is in said first operating position (FIG. 7), and to define a second main fluid path from said inlet port to said second control fluid port when said valve means is in said second operating position (FIG. 8);
• said valve means defining a central reference plane, first pressure port means disposed on a first side of said plane, said first main fluid path comprising said first pressure port means, in a left turn condition and second pressure port means disposed on a second side of said plane, said second main fluid path comprising said second pressure port means, in a right turn condition;
• said valve means further defining first amplification port means disposed on said second side of said plane, and being in parallel with said first main fluid path, and a second amplification port means disposed on said first side of said plane, and being in parallel with said second main fluid path;
• characterized by:
• (a) said housing means defining first and second annular grooves surrounding said valve means, said first annular groove being disposed on said first side of said plane and being in open fluid communication with said first pressure port means and said second amplification port means, and said second annular groove being disposed on said second side of said plane and being in open fluid communication with said second pressure port means and said first amplification port means;
• (b) said housing means defining first and second fluid passages communicating between said inlet port and said first and second annular grooves, respectively, said first and second fluid passages defining a junction downstream of said inlet port;
• and
• (c) first and second check valves being disposed in said first and second fluid passages, respectively, downstream of said junction, whereby:
• (i) in a left turn condition (FIG. 7), said first check valve prevents reverse flow through said first amplification port means;
• and
• (ii) in a right turn condition (FIG. 8), said second check valve prevents reverse flow through said second amplification port means.