Steering system for a vehicle

A vehicle steering system comprising:

• steerable wheels and steering arm means connected to said steerable wheels, and
• steering means for steering said steerable wheels, including
• a movable rack;
• a main steering gear mechanism, including a steering wheel connected to said movable rack for moving said movable rack;
• a steering chamber responsive to movement of said rack, said chamber being divided by a land into first and second chamber portions, said first chamber portion being connected to a first hydraulic line and said second chamber portion being connected to a second hydraulic line, at least a pair of said steerable wheels being connected to a control piston on said land by said steering arm means;
• a reservoir for providing hydraulic fluid to said steering system;
• sensor means for sensing an actual value for an operating condition of a vehicle;
• control means for generating an output signal in response to said sensor means;
• an oil pump;
• motor means for driving said oil pump to pump hydraulic fluid to the steering chamber to directly cause movement of said control piston;
• a first check valve positioned in said first hydraulic line;
• a second check valve positioned in said second hydraulic line;
• an oil pump outlet conduit connected from said oil pump to said first and second hydraulic lines at a location downstream of said first and second check valves;
• said control means being operably connected to said motor means to control said motor means such that said motor means is actuated in response to said output signal to drive said oil pump to provide hydraulic fluid to said steering chamber so that movement of said control piston directly results from hydraulic fluid pumped into said steering chamber by said oil pump.