"Dusty D7R" I designed the roof mount cooling system for this D7R. It was a new machine that was going to work in the char-pile at a Luscar mine site. Char is small pieces of coal and is just like jagged glass and their so very abrasive. Char would destroy the fins in a rad in pretty short order, I was tasked with the job to do something about it!!! The rad was moved to the D7's roof and a thermostatically controlled fan pushed air from the top down and also helped keep char off the front glass. This system worked perfect and was variable speed to boot......