The Walker mower operated by Grimslov High School in Grimslov, Sweden, knows what it's like to mow. The seven-year-old, diesel-powered machine has logged 2,400 hours in just about any type of mowing condition imaginable. Sports turf, common areas, and small enclaves and gardens have posed little challenge for the mower. The small inclines and other hilly terrain that highlights much of the school's 30,000 square meters of lawn haven't either.