"Down pressure from a pair of hydraulic cylinders on this heavy-duty new post hole digger lets you drill right through solid rock or reinforced concrete," says Ron Harleman, Harbor Wisdom Engineering, Appleton City, Mo.

The pto-driven digger is designed for 3-pt. mounting on a 60 hp or larger tractor and uses the weight of the tractor to apply up to 5,000 lbs. of down pressure for high speed drilling.

"It has a simple, clean design with no unnecessary components and sells for only about half as much as other drill-through-rock post hole diggers," says Harleman. "It can drill about 2 in. per minute in solid rock and will go as deep as 3 1/2 ft. A telescoping 18-in. extension can be used to drill a hole up to 5 ft. deep. By pulling a pin the gearbox and auger can be removed and a clevis pin installed on the frame, allowing it to be used as a hydraulic boom to posts."