Patent ID: 7926378

Claim:
A rack and pinion type power steering apparatus, comprising: a deflectable rack shaft slidingly supportable to a gear housing, the rack shaft being supported at a first part and a second part and being unsupported at a third part under a first lower applied load condition, said third part being in closer proximity to said second part than said first part's proximity to said second part, the rack shaft being supported at said first and second and further at said third part under a second higher applied load condition, the rack shaft being deflected only under said second higher load condition to move into compressive contact with a ring-shaped rack bush said first, second and third parts being separated longitudinally, the second part being disposed between said first and third parts, a ring member slidably supported the rack shaft at the first part under both said first load and said second higher applied load conditions, a pressing element supporting the rack shaft at the second part and both said first load and said second higher applied load conditions, said ring-shaped rack bush having at least two different thicknesses in a single cross section which ring-shaped rack bush supports the rack shaft at the third part only under said second higher applied load condition due to deflection of the rack shaft into contact with the ring-shaped rack bush, the ring-shaped rack bush in a single cross section having a first and a second circular arc each having different radii in an inner surface, the first circular arc having a first smaller radius being less than 180° and having a thicker cross sectional area than the second circular arc which said second circular arc has a second larger radius greater than 180 degrees, the rack shaft coming into contact with an inner surface of the first smaller radius only during rack shaft deflection, the ring-shaped rack bush having convex portion along an outer peripheral portion of the bush, engaging with an engaging recess portion in an inner surface portion of the gear housing, the convex portion disposed on the outer periphery of the thicker cross sectional area, a portion of the lamer circular arc always separated from contact with the rack shaft, a first resilient stopper element disposed around a periphery of the rack shaft near said first part, a second resilient stopper element disposed around a periphery of the rack shaft near said third part, an open ring-shaped stopper disposed at the third part against a distal side of the bush, open ring-shaped stopper fixing the bush place and being positioned to arrest inward lateral movement of the rack shaft by abutment against the second resilient stopper element, said ring shaped stopper having an internal diameter which allows deflection of the rack shaft within a predetermined range, and which inhibits deflection of the rack shaft that is greater than the predetermined range.