Patent ID: 6912832

Claim:
A mowing machine comprising a front oriented toward a prime mover providing motive power to the mowing machine and a rear oriented away from said prime mover, said mowing machine additionally comprising: (a) a frame with a hitch point at the front, a pair of wheels at the rear, first and second ends, each of said first and second ends having a lower frame pivot support, the lower frame pivot supports aligned to define a pivot axis, and an upper frame pivot support located above and between the lower frame pivot supports; (b) a header comprising: (i) a front side where a crop enters the header, and a rear side where the mowed crop exits the header; (ii) a first end having a first lower header pivot support; (iii) a second end having a second lower header pivot support; (iv) a first lower header pivot bearing at the first lower header pivot support; (v) a second lower header pivot bearing at the second lower header pivot support, axes of rotation of the first and second lower header pivot bearings being collinear to define a lower header pivot axis; (vi) a first stop structure at the first end, the first stop structure being at a first stop radius about the lower header pivot axis; (vii) a second stop structure at the second end, the second stop structure being at a second stop radius about the lower header pivot axis; and (viii) an upper header pivot support located above and between the lower header pivot supports; (c) a suspension system comprising: (i) a first lower link, comprising a first outer torque tube, said outer torque tube extending from the first lower frame pivot support to the first lower header pivot bearing; (ii) a second lower link, comprising a second outer torque tube, extending from the second lower frame pivot support to the second lower header pivot bearing; (iii) an upper link extending from the upper frame pivot support to the upper header pivot support and generally parallel to the first and second links; (iv) a torsion spring axle, with a spring axis, concentric with the outer torque tube of a lower link and concentric with the header pivot bearings; and (v) a reaction arm operatively attached to the torsion spring axle with a reaction surface at a distance from the spring axis equal to the stop radius.