From what I gather, it appears to be some sort of logging machine made by the LG Le Tourneau company. They made heavy machinery such as bull-dozers, cranes, whatever. It appears the company went out of business some time around the 70's.
It also appears the LG Le Tourneau was a great man, a well respected philantropist (or however the hell u spell it). And he was also a great inventor awarded some 300 patents. His company also built much of the land moving equipment for the allies in WWII as well. I beleive he may have had some dibilitating disease or accident, or whathave you, that confined him to a wheelchair.
He actually sounds like an interesting person...someone I wouldn't mind doing a report on for school.