Patent ID: 7225894

Claim:
An apparatus for use in turning steerable vehicle wheels, said apparatus comprising: a power steering motor assembly connected with the steerable vehicle wheels, said power steering motor assembly includes first and second power steering motors which are connected with the steerable vehicle wheels; a first pump which is connected with said power steering motor assembly and is driven by an engine of the vehicle to supply fluid under pressure to said power steering motor assembly; a second pump which is connected with said power steering motor assembly; an electric motor which is connected with said second pump and is operable to drive said second pump to supply fluid under pressure to said power steering motor assembly; and control apparatus connected with said electric motor to effect operation of said electric motor to drive said second pump when said power steering motor assembly requires fluid in addition to fluid supplied by said first pump, said first and second power steering motors being operable to effect turning movement of the steerable vehicle wheels under the influence of fluid supplied by said first pump until said control apparatus effects operation of said electric motor to drive said second pump, said first and second power steering motors being operable to effect turning movement of the steerable vehicle wheels under the influence of fluid supplied by said first and second pumps when said electric motor is operated to drive said second pump.