| 摘要 |
A booster steering device comprising a combined servomotor and rotary valve control is provided with means for returning the vehicle wheels to a straight ahead position after a steering operation wherein the hydraulic power of the servomotor is utilized for such return movement. The effect is achieved by a cam means actuated by manual steering force to add neutral return energy by twist of a torque rod over and beyond the stress necessary to return the control valve components to a neutral position. It has been found that such overstress results in an overtravel in relative motion of the flow control valve members in returning to neutral position, i.e., overtravel beyond neutral position, briefly. This occurs upon release of a steering force at the hand wheel. As a result of such overtravel, pressure flow to the servomotor is reversed from the direction in which it was going during the terminated steering operation and the servomotor powers the vehicle wheels to stright ahead position. Resiliency is provided in the cam means through a slotted coupling sleeve between the torque rod and a valve component, which stabilizes the construction and compensates for radial play and clearances between connected elements. Means are provided to adjustably position the coupling sleeve and preset the neutral position of the valve members. |
