A three position servo system. The servo system has a servo housing that
has first and second control ports disposed therein in a cavity in fluid
communication with the first and second control ports. A servo piston
having at least one pressure chamber disposed therein is then used to
communicate the pressure within the first and second ports into the first
end of the cavity. Thus, when pressure is applied below a threshold
pressure to both ports a first position is achieved, when pressure is
applied above the threshold pressure in only one port a second position
is achieved, and when pressure is applied above the threshold pressure in
both ports a third position is achieved. Therefore, the servo system
provides three different operating positions.