Motor grader having dual steering mechanisms

Abstract

A dual steering system for controlling the steering of a motor grader is disclosed. The first portion of the steering system comprises a steering wheel connected through a hydraulic steering valve to hydraulic right and left steering cylinders, which are connected to the right front tire and left front tire, respectively. Rotation of the steering wheel causes rotation of the front tires. A second portion of the steering system comprises a first button and a second button that are mounted to a control lever. Actuation of the first button sends a first electrical input signal and actuation of the second button sends a second electrical input signal to an electronic control computer. The electronic control computer generates control signals in response to the electrical input signals and transmits these control signals to a plurality of electro-hydraulic actuators. Actuation of an electro-hydraulic actuator by one of the control signals leads to actuation of the right steering cylinder and the left steering cylinder thereby causing rotation of the front wheels of the grader in one of two directions. Thus, the direction of travel of a motor grader can be controlled by one of two steering systems, one of which permits an operator to maintain contact with a control lever while adjusting the steering of the motor grader.

What is claimed is: 
     
       1. A steering mechanism for a motor grader comprising: an electro-hydraulic control system and a control lever having a first button and a second button;   said electro-hydraulic control system comprising an electronic control computer, a plurality of electro-hydraulic actuators, a hydraulic right steering cylinder associated with one of said plurality of electro-hydraulic actuators and a hydraulic left steering cylinder associated with another of said plurality of electro-hydraulic actuators, said hydraulic right steering cylinder and said hydraulic left steering cylinder each connected to one of a pair of front tires of a motor grader;   said first button transmitting a first electronic input signal to said electronic control computer, said electronic control computer transmitting a first control signal to said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder in response to said first electronic input signal;   said first control signal actuating said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder, and said hydraulic right steering cylinder and said hydraulic left steering cylinder rotating said pair of front tires a first direction in response to actuation of said associated electro-hydraulic actuators by said first control signal;   said second button transmitting a second electronic input signal to said electronic control computer, said electronic control computer transmitting a second control signal to said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder in response to said second electronic input signal; and   said second control signal actuating said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder, and said hydraulic right steering cylinder and said hydraulic left steering cylinder rotating said pair of front tires a second direction in response to actuation of said associated electro-hydraulic actuators by said second control signal, said second direction opposite said first direction.   
     
     
       2. A steering mechanism for a motor grader as recited in claim 1 wherein said control lever is movable along at least one axis; movement of said control lever along said at least one axis transmitting a third electrical input signal to said electronic control computer;   said electronic control computer transmitting a third control signal to at least one of said plurality of electro-hydraulic actuators in response to said third electrical input signal; and   said third control signal actuating said at least one of said electro-hydraulic actuators, said actuated electro-hydraulic actuator actuating one of a hydraulic cylinder, a hydraulic motor, or a hydraulic actuator.   
     
     
       3. A steering mechanism for a motor grader as recited in claim 1 further including a steering wheel hydraulically connected to said hydraulic right steering cylinder and said hydraulic left steering cylinder; rotation of said steering wheel a first direction actuating said right steering cylinder and said left steering cylinder to rotate said pair of front tires said first direction; and   rotation of said steering wheel a second direction actuating said right steering cylinder and said left steering cylinder to rotate said pair of front tires said second direction.   
     
     
       4. A steering mechanism for a motor grader comprising: an electro-hydraulic control system and a control lever having a first button and a second button;   said electro-hydraulic control system comprising an electronic control computer, a plurality of electro-hydraulic actuators, a hydraulic right steering cylinder associated with one of said plurality of electro-hydraulic actuators and a hydraulic left steering cylinder associated with another of said plurality of electro-hydraulic actuators, said hydraulic right steering cylinder and said hydraulic left steering cylinder each connected to one of a pair of front tires of a motor grader;   said first button transmitting a first electronic input signal to said electronic control computer, said electronic control computer transmitting a first control signal to said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder in response to said first electronic input signal;   said first control signal actuating said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder, and said hydraulic right steering cylinder and said hydraulic left steering cylinder rotating said pair of front tires a first direction in response to actuation of said associated electro-hydraulic actuators by said first control signal;   said second button transmitting a second electronic input signal to said electronic control computer, said electronic control computer transmitting a second control signal to said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder in response to said second electronic input signal;   said second control signal actuating said electro-hydraulic actuators associated with said hydraulic right steering cylinder and said hydraulic left steering cylinder, and said hydraulic right steering cylinder and said hydraulic left steering cylinder rotating said pair of front tires a second direction in response to actuation of said associated electro-hydraulic actuators by said second control signal, said second direction opposite said first direction;   a steering wheel hydraulically connected to said hydraulic right steering cylinder and said hydraulic left steering cylinder;   rotation of said steering wheel a first direction actuating said right steering cylinder and said left steering cylinder to rotate said pair of front tires said first direction; and   rotation of said steering wheel a second direction actuating said right steering cylinder and said left steering cylinder to rotate said pair of front tires said second direction.   
     
     
       5. A steering mechanism for a motor grader as recited in claim 4 wherein said control lever is movable along at least one axis; movement of said control lever along said at least one axis transmitting a third electrical input signal to said electronic control computer;   said electronic control computer transmitting a third control signal to at least one of said plurality of electro-hydraulic actuators in response to said third electrical input signal; and   said third control signal actuating said at least one of said electro-hydraulic actuators, said actuated electro-hydraulic actuator actuating one of a hydraulic cylinder, a hydraulic motor, or a hydraulic actuator.