| 摘要 |
An apparatus (10) for turning steerable wheels of a vehicle comprises a housing (12). A rack bar (54) is movable longitudinally relative to the housing (12) for turning the steerable wheels. A pinion gear (68) is located within the housing (12). Teeth (76) of the pinion gear (68) are in meshing engagement with teeth of the rack bar (54). The apparatus (10) also comprises a hydraulic motor (60) for moving the rack bar (54) relative to the housing (12). A valve assembly (98), responsive to rotation of a steering wheel (94) for directing fluid to the hydraulic motor (60), has an actuated position and an unactuated position. The apparatus (10) further comprises a mechanism (156) for dampening longitudinal oscillations of the rack bar (54). The mechanism (156) comprises a yoke bearing (158) which contacts the rack bar (54) with a variable pressure that is dependent upon a velocity of rack bar (54) relative to the housing (12).
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