Posthole Digger Post Hole Augers - Breaking Shear Bolts

[TTTTTT]

For all the 3ph post hole auger experts, I need a little direction/assurance. Just picked up and older auger with a 12" bit I was doing a few test holes in cottage country type earth (a few small rocks and small tree roots). I know it is a good thing to break shear bolts rather than your tractor pto or auger gears, but I was snapping off 3/8" #8 bolts what I thought was a little to frequently. Not being pristine farm field with few rocks etc, is this par for augers running a 12" bit. Had the pto on 540 rpm and idle revs (800). Is the torque that great? Guess it is.

Thanks Dave

 

[art]

When a machine shears bolts it will move a little metal until the hole gets elongated and then they shear quite regular!

I've always perfered hydraulic drive in our area do to the stones. You can just back them out!

 

[2fast2]

I use the same size auger, same RPM or maybe 1000, 540 pto. I haven't broken a single shear bolt, ever (knock on wood) so maybe there is more to it. Check the gear case lube, make sure it is good and turns freely. Also, check your power take off shaft u joints to make sure they're not binding and in some way contributing to this (though I doubt it.) The other question is whether you're going down too quickly and maybe loading things too much. I drill down some, lift and empty the hole, go down farther, lift again, etc.
We plant all our trees this way, put in split rail fence, and it sure beats digging by hand!

 

[tjc1989]

The other question is whether you're going down too quickly and maybe loading things too much. I drill down some, lift and empty the hole, go down farther, lift again, etc.
quote]

This is the way I do it, too, and I have dug through some really thick tough clay this way. Patience is the key, and not expect to dig the hole in 10 seconds. I do this procedure even with a 6 inch auger, let alone a 12 inch. I also bring my auger up near the top to spin off the accumulated soil before going back down into the hole. I have never broken a sheer bolt or damaged a driveline.

 

[TTTTTT]

When a machine shears bolts it will move a little metal until the hole gets elongated and then they shear quite regular!

I've always perfered hydraulic drive in our area do to the stones. You can just back them out!

Good point!

Thanks for the quick comments. Shaft, u joints and auger gears are smooth. I am going down slow and coming up and down. I was down about 3 ' , this auger is a 48". Maybe just hitting something further down.

Dave

 

[MtnViewRanch]

For all the 3ph post hole auger experts, I need a little direction/assurance. Just picked up and older auger with a 12" bit I was doing a few test holes in cottage country type earth (a few small rocks and small tree roots). I know it is a good thing to break shear bolts rather than your tractor pto or auger gears, but I was snapping off 3/8" #8 bolts what I thought was a little to frequently. Not being pristine farm field with few rocks etc, is this par for augers running a 12" bit. Had the pto on 540 rpm and idle revs (800). Is the torque that great? Guess it is.

Thanks Dave

Typically grade 8 bolts are considered a no no. Grade 5 or less is the norm. Something else that you might try, give the tractor no throttle, just let it idle when you are digging. While digging, only dig down 12" at a time, then lift and clear the auger every 12".

Hope that some of these suggestions might help you out.

 

[tjc1989]

Something else that you might try, give the tractor no throttle, just let it idle when you are digging.

Good point. I always just stand beside my tractor with my hand on the lift lever, and at idle. I feel I have better control, plus I more readily hear when the motor and PTO is loading up.

 

[TTTTTT]

Typically grade 8 bolts are considered a no no. Grade 5 or less is the norm. Something else that you might try, give the tractor no throttle, just let it idle when you are digging. While digging, only dig down 12" at a time, then lift and clear the auger every 12".

Hope that some of these suggestions might help you out.

Thanks

That is the way I was doing it other than to clear the bit and hole, I would up the revs just a little. I was using #5's and #8's, they both seemed to shear under a similar load. I guess you are saying before a #8 will go something else will!

Dave

 

[MtnViewRanch]

Dave, just a question on your phd, does it take 1 or 2 shear bolts? I'm asking because I think that most phds only take 1, but mine takes 2.

Just curious :confused3:

 

[sweettractors]

Good point. I always just stand beside my tractor with my hand on the lift lever, and at idle. I feel I have better control, plus I more readily hear when the motor and PTO is loading up.

I had rather be in the tractor seat. I have been on the ground, like you describe and the PHD sheared a pin and it hit me in the chest and stung pretty good. If it had hit me in the eye, it would have put it out for sure. In the seat puts you above the "throw plane" when a bolt shears. Be careful !!-- Ken Sweet

 

[tjc1989]

I had rather be in the tractor seat. I have been on the ground, like you describe and the PHD sheared a pin and it hit me in the chest and stung pretty good. If it had hit me in the eye, it would have put it out for sure. In the seat puts you above the "throw plane" when a bolt shears. Be careful !!-- Ken Sweet

Ouch, but where were you standing ? I meant I was standing beside the wheel, with my arm up over the fender. Not anywhere near the driveline. I guess the right flight path could have made a bee line for my eyes though. I think my chest would have been shiellded by the rear of the tractor and fender. But then I suspect that sitting in the seat and looking back could expose the same vulnerability.

 

[MtnViewRanch]

I had rather be in the tractor seat. I have been on the ground, like you describe and the PHD sheared a pin and it hit me in the chest and stung pretty good. If it had hit me in the eye, it would have put it out for sure. In the seat puts you above the "throw plane" when a bolt shears. Be careful !!-- Ken Sweet

Good point Ken, I think that pretty much anytime that the tractor is being operated, the safest thing is that the operator should be in the drivers area.

 

[MtnViewRanch]

Do your guys phd not have a shield around the area that the shear bolts are? I have to put my shear bolts through a 1" hole to get them through the auger. If the bolt or any part was to get out anyway other than straight down. It would have to find its way through the two 1" holes on the sides.

 

[beenthere]

I wouldn't run a PHD at 540 PTO rpm's. Much too fast, IMO. No need to have that speed. And, a 12" auger bit is a healthy load, and rocks are not meant to be dug up by augers. It is the bane of a PHD in soil with rocks. The shear pins are the safety net. Put heavier bolts in, and that net isn't near as good. But might be worth the risk.

 

[TTTTTT]

Dave, just a question on your phd, does it take 1 or 2 shear bolts? I'm asking because I think that most phds only take 1, but mine takes 2.

Just curious :confused3:

Mine has one shear bolt.

I wouldn't run a PHD at 540 PTO rpm's. Much too fast, IMO. No need to have that speed. And, a 12" auger bit is a healthy load, and rocks are not meant to be dug up by augers. It is the bane of a PHD in soil with rocks. The shear pins are the safety net. Put heavier bolts in, and that net isn't near as good. But might be worth the risk.

The pto is 540 like most, i believe it is geared down in the gear box to something slower. At the 540 setting at idle would't be 540 rpm anyways. As far as the shear bolts, I think you may be right on with the rocks, I am probably catching some. Brought it up just as it was catching and then tried it again and then probably caught the rock which snapped them. If I sence a rock ,I will stop and get a pry bar to check the hole first.

Quote:
Originally Posted by sweettractors
I had rather be in the tractor seat. I have been on the ground, like you describe and the PHD sheared a pin and it hit me in the chest and stung pretty good. If it had hit me in the eye, it would have put it out for sure. In the seat puts you above the "throw plane" when a bolt shears. Be careful !!-- Ken Sweet

Ouch, but where were you standing ? I meant I was standing beside the wheel, with my arm up over the fender. Not anywhere near the driveline. I guess the right flight path could have made a bee line for my eyes though. I think my chest would have been shiellded by the rear of the tractor and fender. But then I suspect that sitting in the seat and looking back could expose the same vulnerability.

Yea when they snap they can fly a bit. It is an older unit with no guards. May have to rig up some guards for anyone who may be standing too close.


Great and useful comments by all!!

Thanks Dave

 

[alco141]

one of the most dangerous implements to use is the post hole digger, it is involved in a lot of accidents, a pto shaft spinning at 540 rpm is moving so fast that if you catch a sleeve in the shaft, by the time the nerve impulses reach your brain that something is pulling on your sleeve you are already wound into the shaft. stay in the seat.

i have thrown rocks the size of a grape fruit 30 feet off the 12 inch auger from my phd. again this rock came out 6 feet high and with enough velocity to fly 30 feet, with enough velocity to kill a person. stay in the seat.

i dont run my phd with 12 inch auger at 540 , i go very slow and up and down to clear the auger very frequently, i still shear a few bolts occasionally i am working in glacial till with a lot of rocks. just go slowly and keep your hand on the 3 pt control watch the shaft and if it digs in or slows pull up and clear the hole. it is a great tool i use mine a lot around the property ,just be careful and stay in the seat. i have seen in the past folks that were wrapped in the pto shaft, they survived but were hospitalized for quite a while.

alex

 

[Chilly807]

Mine has a single 3/8" shear bolt on the input side of the gear box, and two 1/2" bolts holding the auger on the output side.

Usually I dig at just above an idle, maybe a bit higher to spin the dirt off the auger when it's raised.

Sean

 

[2fast2]

I want to clarify the issue of the 540 PTO. My tractor only has one speed for the pto, which is 540 when the engine rpms are 2400. There is an economy setting on some tractors (mine doesn't have that option) which runs the 540 pto speed at a slower engine rpm.
The original poster, and myself, and several other posters have discussed using the post hole digger with engine rpm at idle (800) to 1000 rpm. This will not rotate the auger or the pto shaft at anywhere near 540 rpm. It is slow, still has loads of torque, and is still potentially dangerous. I stay on the tractor seat, ready to lift the auger or kill the pto.
I agree pto shafts should always have appropriate shielding. Don't cut any corners or try to save a few bucks. When the accident happened with my neighbor while he was helping at the nearby dairy farm (many years ago) and his shirt caught in the pto, it pulled him in and nearly destroyed his arm. He has a permanent disability and the farm had a huge lawsuit it had to settle.

 

[sweettractors]

If someone walks within 50 ft while I am digging, I stop the tractor until they leave. Shearpins thrown off a input shaft with no shielding or the 2 bolts that hold the auger to the output shaft have been known to shear off and can fly a long way in the air. Ken Sweet

 

[MESSMAKER]

one of the most dangerous implements to use is the post hole digger, it is involved in a lot of accidents, a pto shaft spinning at 540 rpm is moving so fast that if you catch a sleeve in the shaft, by the time the nerve impulses reach your brain that something is pulling on your sleeve you are already wound into the shaft. stay in the seat.

i have thrown rocks the size of a grape fruit 30 feet off the 12 inch auger from my phd. again this rock came out 6 feet high and with enough velocity to fly 30 feet, with enough velocity to kill a person. stay in the seat.

i dont run my phd with 12 inch auger at 540 , i go very slow and up and down to clear the auger very frequently, i still shear a few bolts occasionally i am working in glacial till with a lot of rocks. just go slowly and keep your hand on the 3 pt control watch the shaft and if it digs in or slows pull up and clear the hole. it is a great tool i use mine a lot around the property ,just be careful and stay in the seat. i have seen in the past folks that were wrapped in the pto shaft, they survived but were hospitalized for quite a while.

alex

Wise words. PHD can hurt you in seconds.