Shear bolt madness

[kfeuerherm]

I thought of that. Perhaps with the extension to my dremel. But the trick would be to be sure I've got it aligned correctly... Don't want to make bogus holes in the shaft....

Thanks for the reply!

 

[dsmiley]

How about a little more info? Is this a BX2750D blower? Is the broken shear bolt for the fan or auger? Is the broken bolt an OEM bolt with reduced shank areas at the shear points?

I have sheared a minimum of 15 OEM bolts (5 so far this year) with my BX2750D and have been able to push every shank out with very little effort once I got the holes lined up with the shank. The key is getting them lined up.

 

[kfeuerherm]

I was replying to a thread re BX2750D and specifically to an entry about the pin at the fan, so I didn't repeat that info, but yes, that's the situation.

As for lining them up: 1) I put in a bolt and tapped with a hammer all the way around. As per the post I was replying to I got the impression it lined up when I had the hole in the same orientation as the hole one inch ahead of it (slight catching of my tapping bolt in that position), but it made no difference. No amount of banging made the slightest difference. I find that odd--I've replaced the bolts in the augers a few times with no real problem, which is why I'm stumped... though admittedly it's harder to access here.

I should post a photo I guess but it's dark now and I'm heading on a trip in the morning before it gets light. I was hoping to ponder the problem a few days so I could sort it out when I'm back (on Friday)....

 

[dsmiley]

The two holes in the fan shaft do line up; I replaced one within the last week. I think you should keep trying before drilling.

 

[like2wheel]

Yeah, drilling sounds like a bad idea to me, especially since the pin is a grade 8, & I'm sure the shaft is softer than that.

My fan has a considerable amount of fore & aft play, so in addition to lining it up with the holes on the end of the shaft, I slide it forward & back while tapping on a right angle pointyish thing that I keep for this task. Using something pointy helps so that you dont have to find the exact spot to hit without catching the edges. The sound changes when you find it, then you only need to adjust the fan to let the slug pass out thru the hole.

 

[kfeuerherm]

I forgot to add, in response to the earlier query, that yes it is an OEM bolt. All in all, I seem to be lucky, in the several years that I've run this thing, I've broken maybe 2 or 3 auger bolts, and this is the first time I've broken the fan bolt.

Still... I just can't imagine it ought to be this hard to fix... even if I am doing it in an unprotected area.

I'm leery of the drilling idea too. As I can't be sure I've got it just rightly set, sounds like I could easily compound the problem.

We considered trying to remove the augers, removing the holding clip to slide the fan forward, or trying to access the pin with a longer object through the eject area; but doesn't seem designed for any of those options

Oh, and I did try a narrower object too, like a finishing nail punch. Didn't help.

 

[muskoka kubota guy]

I have a B2920, not sure what the blower model is. I have often struggled getting the sheared fan pin to drop out of the hole. A bushing causes the fan to spring slightly forward and the shaft and fan hole are no longer in perfect alignment. I remove the C clip at the front of the fan and pull the fan fully forward. The sheared pin then drops out. Return the fan to it's location and insert new pin. If the holes are still not perfectly aligned, the new pin can be sharpened slightly. I will be taking the blower fully apart in the summer and make whatever modifications are necessary to stop this problem.

 

[CalG]

The single stage blower on the Bolens HT-23 shears bolts too often. Mostly in early winter before the stones get cleared away.

I purchase a box of 1/4 inch grade 3 bolts and a matching box of nuts every few years.
The shear joint is also a coupling between chain drive shaft and drive gear box. I've put a loveJoy coupling there to provide some shock compliance, It seems to work.

When a bolt shears, It is often difficult to see the hole locations. I like to pull up to the shop door, and grab a heat gun to melt away the snow and ice. That makes observation of the holes much easier. I use a stout taper punch to start driving out the remaining center section of the shear bolt. Then finish with a long straight punch that doesn't bind in the hole.
The new bolt is tapped in, the nut just barely snugged down, then a few quick blows of the hammer upsets the bolt threads so the nut is NEVER coming off. No need of Nylock nuts or any of that ;-)

Warm wet snow is the pits. This recent cold snow has been problem free.. The blower can be pushed into snow until the engine revs drop considerably without shearing the drive. I think about it every time however. ;-)

 

[rbarker]

I forgot to add, in response to the earlier query, that yes it is an OEM bolt. All in all, I seem to be lucky, in the several years that I've run this thing, I've broken maybe 2 or 3 auger bolts, and this is the first time I've broken the fan bolt. Still... I just can't imagine it ought to be this hard to fix... even if I am doing it in an unprotected area. I'm leery of the drilling idea too. As I can't be sure I've got it just rightly set, sounds like I could easily compound the problem. We considered trying to remove the augers, removing the holding clip to slide the fan forward, or trying to access the pin with a longer object through the eject area; but doesn't seem designed for any of those options Oh, and I did try a narrower object too, like a finishing nail punch. Didn't help.

I've broken 3 or 4 of these bolts and from my experience each time is different. I'm not telling you anything you don't already know but the key is getting it lined up correctly. I have a full set of pin punches but I've found ( thanks to someone on this forum) that a 16 penny nail is very effective. The bolt hole DOES line up with the exposed hole in the shaft but there is some play forward and back so the nail helps you to "feel" the end of the pin. Sometimes the end of the broken bolt will leave a burr instead of breaking clean so try pushing it out from both sides. That has been the answer for me on more than one occasion. If you put the PTO in neutral you can spin the whole thing by hand to get better access. (Tractor off please!). It is not a viable choice to try to disassemble the blower to get to the fan drive shaft. I would also never consider drilling!

Let me finish by saying that I have felt your frustration with a stubborn pin on more than one occasion. Patience and perseverance along with moral support from the forum here has gotten me through so far.

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[woodchipper]

Good alignment is a must. When you will drive out the brocken pin, and have the new one in place, using a flat chisel, mark both sides with one good strike. This way, next time the pin brakes, and you try to match the holes, they (the both halfs that are now marked in perfect alignment) will align perfectly on the first try. Good luck, and stay warm.

 

[kfeuerherm]

Good alignment is a must. When you will drive out the brocken pin, and have the new one in place, using a flat chisel, mark both sides with one good strike. This way, next time the pin brakes, and you try to match the holes, they (the both halfs that are now marked in perfect alignment) will align perfectly on the first try. Good luck, and stay warm.

Thanks to everyone for the advice and support so far. When I get back in a few days I'll try some of these things. We did consider pulling off the C-clip but were afraid of breaking it....

I'm definitely going to check to see to what extent the actual hole lines up with the advance hole when I do get it fixed, and mark it if need be!

Too bad they didn't make the blower outer shaft just an inch or so longer (which would have easily been feasible) just to make it easy access....!

 

[kfeuerherm]

I did manage to snap some shots before we left home in the morning as the tractor is by the front porch and the light comes on. But it was -25C (-41C with wind chill, and -40C = -40F so you know what I'm talking about!) and my hands froze up in the time it took to do it and I had to go in and warm up in between.

You can see the hole by the fan. Sticking a pin in that hole does get a catch, but because of the position of the blade there's no room to manoeuvre. Oddly, sticking a pin in the other side where there is slightly no room gets me no catch. I don't get it.

I'm wondering: if I did pull the C-clip off, how far does the fan come forward? all the way? any chance of poking around the hold behind the fan? looks pretty tight....

Temperature staying the same all week so I lose nothing by being away...

 

[dsmiley]

On my blower the shear bolt holes are very snug to the point that when aligned I sometimes have to tap a new bolt in. So alignment has to be near perfect to remove the old shank. Twice I have thought that a burr was preventing removal so I got a punch and tried to hammer it out. It turned out that both times was due to misalignment.
If the shear bolt hole and the other shaft hole are somewhat aligned when you "get a catch" I would align them and try tapping on the pin while moving the fan ever so slightly around. I think if you get it aligned the old shank will come easily if the bolt is OEM.

I agree with your assessment that the fan hub should come outside of the shroud area. It would make changing bolts a piece of cake.

Maybe you can peek in the hole using an inspection mirror.

 

[kfeuerherm]

Good suggestion. I'll try that when I'm back. Thanks!

 

[muskoka kubota guy]

This is what I have done on a half dozen occasions; Move the augers so there is maximum clearance directly in front of the fan. Expand and slide the C clip back so that it is close to, but not touching the gearbox. Rotate the fan so that the blades will clear the housing. It will not pull forward in just any position. Use a bit of penetrating oil and work the fan back and forth until the shaft hole is fully clear of the fan. The remains of the sheared pin should drop out. Return the fan to its proper position, if the holes do not align, use a pin punch from one side to help align them. Insert new shear pin, it may help to put a slight a taper on the end of the new pin. Tap the new shear pin into place. Replace C clip.
I believe the problem is caused by the fan bushing which is not seating properly and causing forward tension on the fan. This summer I will be investigating and repairing.

 

[kfeuerherm]

Aha! Sounds like a practical solution. Will give it a try. Thanks.

 

[Soundguy]

Yeah, drilling sounds like a bad idea to me, especially since the pin is a grade 8, & I'm sure the shaft is softer than that.

My fan has a considerable amount of fore & aft play, so in addition to lining it up with the holes on the end of the shaft, I slide it forward & back while tapping on a right angle pointyish thing that I keep for this task. Using something pointy helps so that you dont have to find the exact spot to hit without catching the edges. The sound changes when you find it, then you only need to adjust the fan to let the slug pass out thru the hole.

i'm not sure why you think drilling is a bad idea just because of it being a grade 8. Just use the correct tool for the job...

 

[kfeuerherm]

Someone suggested the shaft was softer, so there is risk of damage. I wouldn't know, myself....

 

[dsmiley]

i'm not sure why you think drilling is a bad idea just because of it being a grade 8. Just use the correct tool for the job...

Well, for one thing you will never know the correct spot to drill. And 2, even if you did, the old shank will just spin in the shaft = no drilling. You say, "just use the correct tool for the job". Please tell us what the correct tool is to remove that old shear bolt shank?

 

[rbarker]

I did manage to snap some shots before we left home in the morning as the tractor is by the front porch and the light comes on. But it was -25C (-41C with wind chill, and -40C = -40F so you know what I'm talking about!) and my hands froze up in the time it took to do it and I had to go in and warm up in between. You can see the hole by the fan. Sticking a pin in that hole does get a catch, but because of the position of the blade there's no room to manoeuvre. Oddly, sticking a pin in the other side where there is slightly no room gets me no catch. I don't get it. I'm wondering: if I did pull the C-clip off, how far does the fan come forward? all the way? any chance of poking around the hold behind the fan? looks pretty tight.... Temperature staying the same all week so I lose nothing by being away...<img src="http://www.tractorbynet.com/forums/files/kubota-owning-operating/412265-shear-bolt-madness-blowerfanhole-jpg"/><img src="http://www.tractorbynet.com/forums/files/kubota-owning-operating/412266-shear-bolt-madness-blowerwhole-jpg"/>

You are probably already aware of this but you can clearly see that the blower fan is not lined up with the shear bolt hole in your first picture. I would rotate the augers until the unused hole in the fan shaft is closer to twelve o'clock and then try lining the fan up to it again. Might help to get all the snow out as well.

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