Snow Going through second stage bolts

[jrogers]

Here is a picture of a couple of the many sheared bolts:



More interestingly, here is one that was in the tractor for about 10 minutes:



You can see how it is already getting beat up. Looking at the tab where the shear bolt goes in, it is a bit loose, especially the back tab. I tried wrapping the bolt in some metal putty stuff that should harden and fill the gap. It seems like the correct solution would be to weld the hole and redrill it, but that seems like it would be hard to do without a lot of disassembly.

On another note, I pulled the drive shaft apart, and the shaft is not square, but slightly rectangular, so there is no way to assemble it where I would cause the phase problem previously mentioned.

 

[Dave M7040]

jrogers

I pasted an early post of your which clarifies a few things.

When I said second stage, I meant not the auger but the fan (the vertical section). I rarely shear the auger bolts. The bolts I have been getting are from the kubota dealer, so I am assuming that they are giving me the right thing. We have had some warming and cooling, so the driveway has had some 'traction sand' put on it, which has some coarser sized pebbles in it that may be causing the issue, maybe a 1/4" in diameter. Thanks for the advice on running the blower at full speed as well as torquing the bolts tight, those are both things that I have been wondering about. I took the time today and greased all of the fittings on the blower. It probably won't help but certainly won't hurt.
Below Dave M7040
Is this image of a new blower's fan shear bolt the same as you blower?

Do you have a venier caliper, even a plastic one from home depot.

The usefullness of the probe coming out is to measure the depth of a hole. In your case you are going to press the big end where the probe comes out against the area where the shear bolt goes in and extend the probe until it is just flush with the other side of the home.

Lock the caliper in that position with the small thumb screw.

Place the probe against the underside of the head of the shear bolt and take a photo which will show where the depth of the hole is on the shank area of the shear bolt.


Can you post a picture of the bolt in your second photo in place on the blower. Also measure the length of the bolt from the top of the head to the end of the threads at the tip.

The thread area is all deformed. The threads should be outside where the shearing action is to happen.
The threads are just to keep the smooth shank of the shear bolt in place until the time its protection is needed.

For the threads to get beat up near the un threaded shank tells me something is amiss with the amount of threads on the bolt shank.

Would you post a picture of the second photo bolt in place be certain to get a shot of the head of the bolt.

If as I suspect, when the second bolt is in place, there is no smooth shank just at the edge of the shear bolt hole, then I think you need a longer bolt or a bolt where the shank is smooth for a greater distance.

Where do these bolts come from? A Kubota part # or a general supplier of bolts and nuts. There is a length of bolt where the amount of thread is suddenly reduced compared to the lower size.

I think it is 1-1/2" has fewer threads than 1-1/4".

Looking forward to seeing the requested pictures as I think it will explain a lot.

Dave M7040

 

[PILOON]

Well I am a new member to the sheer bolt club as I have been sheering like 3-4 /hr , this on my fan.
What has happened is that I used hardware store bolts that were supposedly graded but I guess they weren't and as a result they stretched and messed up the holes so they no longer simply shear.

So what I'm doing is drilling out to oversize, in this case 5/16, and hope that I'm good to go.
Changing shear bolts every 15 mins is no fun!

 

[jrogers]

So what I'm doing is drilling out to oversize, in this case 5/16, and hope that I'm good to go.
Changing shear bolts every 15 mins is no fun!

The problem is that if you move up to a larger size hole and shear bolt, you are also moving up to a higher shear force, unless you are able to find bolts that are rated for the same shear force as what you where previously at.This may be possible by getting a bolt with grooves in it, but I don't know what they want for the rated shear force, I just buy the Kubota bolts.

 

[JCByrd24]

I think I'm correct in that you have a different shear bolt arrangement than what Dave shows in post #92, in that you have a hub with the shear bolt off to the side. I think there was a picture earlier. This is very similar to a JD and the distance from the center of the shaft looks about the same or shorter. The JD uses 1/4" grade 5 vice 2. I think you could easily go to a 5 if you have not already without fear.

With that type of arrangement there should be no wear before shearing in my opinion. The bolt should be snug enough that it's holding the two hubs together and the friction imparted means the two hubs don't rattle or move with respect to one another. The unidirectional loading should mean the same thing really, but if loose the engagement and disengagement of the PTO could wear the holes/bolts. The wear you show in your photos suggests to me it's not tight enough. This would not be true with the design Dave posted and in my opinion that is a worse design as once those holes started to wear it would get progressively worse.

This brings me to another question. How is the PTO engaged on your B-series? With a clutch you control or instantly via an electric clutch of some sort. If the latter I would caution that you need to drop the engine speed down to just above idle when engaging the PTO. My Yanmar engages with the same clutch pedal as the tractor so I can feather the engagement even at full throttle.

 

[Dave M7040]

Well I am a new member to the sheer bolt club as I have been sheering like 3-4 /hr , this on my fan.
What has happened is that I used hardware store bolts that were supposedly graded but I guess they weren't and as a result they stretched and messed up the holes so they no longer simply shear.

So what I'm doing is drilling out to oversize, in this case 5/16, and hope that I'm good to go.
Changing shear bolts every 15 mins is no fun!

Piloon
So you live in Quebec where RAD is.

Go and pound on their door for a solution.

On a more serious note, to be safe post a picture of what you have and the shear bolt area where you are having problems.
If we don't understand exactly what you have, you could receive advice that would or could be damaging.

I sent an email to RAD. I received a reply from CustomerService@Kubota.ca

If you don't have the latest fan hub with flange design and related flange part on the fan shaft, then all efforts are wasted and you could end up with a gear box in pieces which, I am told is $700.

If you or anyone else want to see the lengthy email I replied to the Kubota rep, send me a pm with your email and I will forward it to you as it is too long to post here.

Dave M7040

 

[PILOON]

Well I am a new member to the sheer bolt club as I have been sheering like 3-4 /hr , this on my fan.
What has happened is that I used hardware store bolts that were supposedly graded but I guess they weren't and as a result they stretched and messed up the holes so they no longer simply shear.

So what I'm doing is drilling out to oversize, in this case 5/16, and hope that I'm good to go.
Changing shear bolts every 15 mins is no fun!

Well so far so good.
Just did 2 drives, about 2 hours of tractor time all with the same bolt so life is good.
In many cases I had a full load, enough to want to lower the RPM's so I was working to the limits.
Being somewhat leery of damaging things I used 5/16 regular rather than graded bolts and they held up as I hoped.
Come decent work weather (summer?) I'll install bushings and return to 1/4" bolts but to do that the fan needs removal which means total take down and at which time I'll probably renew bearings as well and do a general overhaul.

On the positive side I have a good base (read stone free) so should not catch any sheer breaking stones or other junk in which case that one 5/16" bolt might just last the remaining season.
Also intend to add belting to the paddles to close up that gap, fact is the 'generous gap' is my main cause of troubles as stones get wedged in there and trip the sheer bolts.

 

[JWR]

Looking at Dave's post #92 -- any of you using that design (shear bolt thru the shaft) are much more susceptible I think. In that design tightening the bolt does nothing to snug the shaft and the housing together because the housing metal is too thick. In that setup you are totally dependent on the bolt being tight in the hole and have no control over it. If the hole has become distorted due to repeated breakages the problem will keep getting worse. If it were mine I would do as Piloon said and drill it out to use 5/16" bolts. But in doing that you have to be very careful not to drill an enlarged imperfect hole even if it is 5/16". Another thing is to "search the bolt bins" and purposely pick a shear bolt with just enough threads to tighten against the housing hole and NOT enough threads to go down inside the housing. Point is you don't want threaded area in the region of shear. I would not be afraid of using 5/16" grade 2 bolts at all.
Another thought about those of you shearing really large numbers of pins even on light snow and in very short time, that circumstance is what has baffled most of us approaching 100 posts now. If it is THAT bad (and a used blower where you cannot just insist on dealer assist) I would set the whole rig up to run in the open on concrete -- no load, no snow. As light a load as some mentioned and still getting shear it will probably do it sitting there in the open under what SHOULD be no-load. That way you can test for "slop" in each pin area, noises, wobble, etc. Might even wonder if bearings are on the way out and periodically jambing and resisting turning.

 

[aczlan]

Another thing is to "search the bolt bins" and purposely pick a shear bolt with just enough threads to tighten against the housing hole and NOT enough threads to go down inside the housing. Point is you don't want threaded area in the region of shear.

Yes, I would pick a shear bolt that has a shoulder long enough to hit both sides of the shear area.
If needed, you can shorten the threaded section to be just longer than the nut.
I had to do that with the shear bolt on our hay baler.

Aaron Z

 

[jrogers]

Yes, I have the updated shear bolt setup in mine:



Here is the bolt in the package from Kubota:



The total distance of the two flanges lined up is around 3/4". The thread on the bolt could be 1/4" shorter in my opinion.




And here is the head of the bolt. This is a grade 8 bolt, right? Seems like no where to step up to other than to go to a 5/16".



The last bolt I pulled out had a bit of a bend to it, even though it was only in there a short time. They seem to loosen up quickly. I assume that it is stretching the bolt.

I can get pretty good access to the two sides of the flange. It seems like a good, permanent solution would be to weld up the holes and redrill them, as they are a bit loose right now. I will try and find another grade 8 1/4" bolt with a longer flange (less threads). The JH label on bolt head indicates the Chinese manufacture. Maybe they are not really grade 8 or they have some manufacturing problem?