Draw bar for a motor grader

An improved motor grader circle mounting bar structure which has a connecting end provided with an integral ball which is adapted to be attached to a motor grader frame for universal movement about its own center, and which has a carrying portion adapted to be suspended from said frame by means which may pivot the mounting bar about said ball center, and said carrying portion being adapted to carry a circle structure for a grader blade, said improved mounting bar structure comprising, in combination:

• a box-like beam the width of which increases from its connecting end toward said carrying portion, said beam having side plates, a top plate and a bottom plate both of which fill the entire space between the side plates from said connecting end to said carrying portion, and longitudinal and transverse internal vertical webs, the increase in width of said beam from its connecting end to the intersections of the side plates with a transverse plane which is near to but outside the circle being such that the side plates lie entirely between,
• a. an isosceles triangle plotted between the ball center and said intersections and
• b. a parabola plotted between said center and said intersections
• and a mounting bar carrying portion of box-like cross-section which is structurally integral with the wider end of said beam, said carrying portion having side plates which are extensions of the rear ends of the beam side plates, and having top and bottom plates integrally joined to said carrying portion side plates and integrally and continuously joined to the entire width of the beam top and bottom plates.