Bootstrap power steering systems

A power steering system for a vehicle, said system having at least one power cylinder, said system comprising:

• a rotary control valve having a first member rotatable with respect to a second member from a centered position to non-centered position, said first and second members formed to define at least one pair of input orifices, at least one pair of output orifices, at least one return orifice and a chamber interconnecting said at least one pair of output orifices and at least one return orifice, said input orifices and said output orifices being open when valve is in said centered position, said at least one return orifice being progressivelyu opened as said rotary control valve is moved from said centered position to said non-centered position, thus enabling an increasing flow of hydraulic fluid through at least one of said at least one pair of input orifices, at least one of said at least one pair of output orifices and said chamber, and out of said opening return orifice;
• a pump having a reservoir, said pump producing a variable pressurized flow of hydraulic fluid having an output pressure, said flow being delivered to said at least one pair of input orifices and being returned to said reservoir from said at least one return orifice, said pump having means for regulating said output pressure, said means for regulating being responsive to a control pressure;
• and
• means for selecting a pressure value from said chamber and delivering said pressure value as said control pressure to said means for regulating whereby said output pressure of said pump is varied response to a change in said control pressure.