Patent ID: 7789427

Claim:
A chassis frame comprising: right and left side rails running lengthwise of the frame and comprising respective channels each of which has an interior bounded by a vertical wall and horizontal top and bottom flanges that extend from top and bottom of the vertical wall toward corresponding flanges of the opposite side rail, a lower channel running lengthwise of the frame and comprising a horizontal bottom wall that bridges the side rails and is disposed against the bottom flanges of the side rail channels and vertical side flanges that extend from opposite sides of the bottom wall upward and against a face of a respective one of the vertical walls that is exterior to the interior of the respective channel; an upper channel running lengthwise of the frame and comprising a horizontal top wall that bridges the side rails and is disposed against the top flanges of the side rail channels and vertical side flanges that extend from opposite sides of the top wall downward and against the exterior face of a respective one of the vertical walls of the respective channel; and spacer structure disposed vertically between the upper and lower channels and horizontally between and in abutment with the side rail channels wherein the spacer structure comprises respective spacer structures at opposite lengthwise ends of the upper and lower channels.