초록 ▼

A wheeled vehicle which has two members connected by an upright joint has a pair of hydraulic steering jacks coupled between the members on opposite sides of the joint, and the vehicle is steered by normally causing both jacks to pivot the members under the control of a steering wheel. The hydraulic

A wheeled vehicle which has two members connected by an upright joint has a pair of hydraulic steering jacks coupled between the members on opposite sides of the joint, and the vehicle is steered by normally causing both jacks to pivot the members under the control of a steering wheel. The hydraulic steering system utilizes a constant displacement pump driven by the vehicle engine, and includes a follow-up means which senses the pivoting movement and deactivates the jacks when turning of the steering wheel ceases, so the operator may steer the vehicle by manipulating the wheel in a conventional manner. Selector valve means in the hydraulic system functions to automatically direct all or nearly all of the fluid to one jack if pump output is insufficient to drive both jacks as fast as is called for by the operator\s rotation of the steering wheel.

대표청구항 ▼

In a wheeled vehicle having two members connected by an upright joint about which the members pivot for steering the vehicle, a steering wheel on one of said members, a hydraulic system including two fluid operated jacks coupled between said members on opposite sides of the joint for effecting said

In a wheeled vehicle having two members connected by an upright joint about which the members pivot for steering the vehicle, a steering wheel on one of said members, a hydraulic system including two fluid operated jacks coupled between said members on opposite sides of the joint for effecting said pivoting, each of said jacks having a head end and a rod end provided with fluid connections, a constant displacement hydraulic pump in said system which is driven from the vehicle engine, a three position control valve in said system, a valve control element operable by rotation of the steering wheel for moving said control valve between a neutral position and two offset positions for simultaneously driving both jacks to pivot the members in a desired direction, and follow-up means in said system which includes a master cylinder coupled between the wheeled members for detecting pivoting at the joint, together with a slave cylinder hydraulically connected to the master cylinder for synchronized movement therewith, said slave cylinder being coupled to the valve control element to move said element in a direction opposite to that produced by turning of the steering wheel, the improvement comprising: means for sensing back pressure in the system resulting from insufficient fluid volume for driving the jacks and followup system as rapidly as is required by the speed of steering wheel rotation; selector valve means which has a normal position, said selector valve means being movable from said normal position in response to the sensing of back pressure by said sensing means; and fluid connections between said selector valve means, the control valve, and the jacks to selectively direct substantially the entire flow of fluid from the pump to one of the two jacks, which is then an active jack, upon movement of the selector valve means from said normal position, while the other of said jacks is substantially idle.