Safety with Post Hole Diggers

Richard L. Parish, PhD, PE

Post hole diggers mounted on tractors and powered by the tractors’ PTO shafts are useful tools for setting posts, planting trees, and other uses, but they can cause serious injury if not used correctly. The Farm Equipment Manufacturers Association (FEMA) is an organization whose members manufacture post hole diggers. They have developed some guidelines to help you use their products more safely.

Current post hole diggers manufactured by FEMA members include, as standard equipment, guards or shields for auger adapters, PTO drivelines, and PTO universal joints and connections. Older machines can often be retrofitted with these shields. These shields are important and should be maintained and kept in place.
It is important that all operators read and understand the operator’s manual provided with the machine. If you don’t have a manual, the manufacturer can provide one.
Most post hole diggers incorporate a shear bolt – the bolt that attaches the auger to the gearhead often serves this purpose. You should never replace the shear bolt with a longer bolt – it would make entrapment more likely. Nor should you replace the bolt with a harder bolt – that could damage the machine and could cause the auger to come loose in use.
Most importantly, post hole diggers are designed and intended for one-man operation. There should be no one within 25 feet of the post hole digger except the operator in the tractor seat. Never allow anyone to approach the digger or touch any part of it when operating. No one should use their hands to place the point of the auger for starting the hole; do that strictly from the tractor seat using the tractor hydraulics. Some older post hole diggers had provision for an arm sticking out the back to allow a second person to pull down on the arm and add down-pressure for digging in hard ground. Newer machines do not have this feature, and it should not be used even on older machines. No one should be that close to the auger and/or powershaft when the digger is operating.

Post hole diggers are useful implements and can be used safely, but can also cause serious injuries including amputations and death if misused. Treat them with respect. Most importantly, keep everyone but the tractor driver at a safe distance when a post hole digger is in use.