It's all in the field specs. Go
here, then right-click on Field Specs & Documentation, and save the specs to your local disk. Page 5 of the Field Specs drawing shows the height as 32 inches, measured from the platform surface to the top of the bar. Since the bar is made of 0.85 inch diameter pipe, clearance under the bar is nominally 31.15 inches. Page 7 of the Field Components Mods drawing shows the Atlas ball diameter as 30 inches. So nominally the Atlas ball clears the bar by 1.15 inches.
Rule <G11> says field tolerances may be as much as +/- one inch. So in the worst case if the Atlas ball diameter was 31" and the bar height was 31", then the ball would not clear.
To keep this from happening at the St. Louis FVC Championship, we used a 30 inch gage made of good grade plywood to verify that no Atlas balls were oversized, and adjusted inflation accordingly. You've probably noticed that they aren't generally round
(thats why they don't roll straight), so we gaged the maximum width.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)