My apologies. I was under the impression that we were discussing a machine that was designed. This looks like a homemade rig. This is a montage of ideas passed off as a design. There may be no logic that applies to the manlifter at all as to why the wheel size is different. It may be as...
Before I get inundated with rebuttals, let me clarify that it would be only a slight increase. That being said, in a world where field personnel continually over step the safety specifications of the equipment they are working with, that slight edge may make the difference in someone's life...
Just a guess without seeing it, but a higher front axle would increase the effectiveness of the counter-balance weight thereby resisting tip-over. (Weight being below the balance-horizon)
