Three-Point Auger Bores Post Holes Like A 10-ton Excavator

By Larry Stewart, Executive Editor | September 28, 2010

RockyRoo says its post-hole auger is designed to equip a 50-hp tractor with digging capability comparable to a hydraulic digger attached to a 10-or 15-ton excavator.
Hydraulic Cylinder Illustration
A heavy-duty hydraulic cylinder provides positive down pressure on the patented tail curve. The sub frame ties the draft links and the top link together to fix a mounting point for the cylinder and tail.

RockyRoo says its post-hole auger is designed to equip a 50-hp tractor with digging capability comparable to a hydraulic attachment mounted to a 10- or 15-ton excavator. The manufacturer says its users in Australia commonly claim to achieve three or four times greater output with the RockyRoo than with other three-point-hitch-mounted attachments.

In soft ground, the RockyRoo will dig a 4-foot hole in 5 seconds. Because it's mounted on a utility tractor, the attachment requires significantly less travel time between holes, as well as less set-up time at each hole location than does dedicated hole-digging equipment.

Amerequip very recently licensed the RockyRoo and began building and marketing the Australian-designed attachment, so most user experience is in Australia. Amerequip says there are thousands of the units working Down Under, with "extensive service in a wide range of severe soil conditions—including rock, snow, frozen ground, solid granite and sedimentary shale."

RockyRoo has patented the curving arms of the attachment's frame, claiming they're responsible for the machine's productivity advantage. The high-grade, high-tensile steel frame is engineered to withstand the maximum stress the tractor can deliver.

The tractor's power take-off drives the auger, and a center-mounted hydraulic ram provides the down force. The curved arms minimize stress at the ram thrust points and bring all the relevant angles together at a convergence point that yields substantially higher down pressure than other three-point-hitch post-hole augers.

RockyRoo's heavy-duty hydraulic cylinder applies down pressure on the curved tail. No other external force is needed. The ram is built with a heavy-wall barrel and oversize parts.

A three-point sub frame ties the tractor's draft links and the top link together to provide a rigid, fixed mounting point for the hydraulic cylinder and curved tail. With this design, control of post-hole depth does not depend on travel of the three-point linkage.

RockyRoo augers are specially manufactured by a company called Pengo. TriMax augers use a new generation of Tri-Flow Pilot bit with solid carbide teeth up the flighting. Amerequip says it ensures starting the hole straight and keeping it straight. Additional carbide-tipped teeth are fixed in pockets along the auger's cast cutting head. Pocketing these teeth eliminates the need for retaining bolts, and the accompanying problems with wear and difficult removal. The interface between gearbox and auger is heavily reinforced with double-fluted spirals.

Manufacturer-suggested retail price for the RockyRoo is $3,300. For more information on the machine, and a demonstration video, go to