Jerry L Whitlow

US Patent:

43378323, Jul 6, 1982

Filed:

Jun 27, 1980

Appl. No.:

6/163565

Inventors:

Jerry Whitlow - Paragould AR

International Classification:

A01B 6104
A01B 6908
E02F 376

US Classification:

172265

Abstract:

A land plane for leveling or grading the surface of a land area. The plane includes a frame defined by a center section and end sections pivotally connected to the center section, with each connection permitting relative physical movement about an axis transverse to the longitudinal axis of the plane. A first hydraulic system is provided for pivoting the end sections about their transverse axes for raising and lowering the center section with respect to ground level, wherein the system includes a device for equalizing fluid between hydraulic cylinders carried by the end sections to permit adjustment of the grader assembly with respect to ground level under different operating conditions. A second hydraulic system is provided to permit selective steering of the rear wheels in response to the front wheels through either pivotal movement of a tongue connecting the plane to a tow vehicle or from a separate hydraulic power source carried by the tow vehicle, wherein the system includes means for purging itself of entrapped air. A biasing mechanism is provided for the grader assembly to permit tripping of the blades when the applied force encountered during grading exceeds the predetermined bias force.