BX2750 Shearing Pins

[kevinj]

Yes he does. When he first got the blower and sheared his first pin, he asked me about the auger placement, so he's had that correct since the beginning.

Just so everyone knows; the augers run out 180°, not matched,

 

[kevinj]

Dyer,

I had another thought. Are all the bearing screws tight???? and the mounting for the gear box???

Maybe the auger shaft is moving sideways under load and catching the augers on the gearbox.

When mine was new everything was loose, it did not shear pins however.

 

[Dyer retired]

You may be on to something. Those are grooved bolts. Over torque could snap them off.

It would be nice to see the broken bolts to see if they sheared or broke in tension.

The augers are not bearing dependent nor do the touch anything but the snow unless you hit banks or pick up a stick.

I have chewed into some pretty good plow truck banks and only ever sheared one when I picked up a tree branch in the snow.

Well, you and Radioman might have found part of the problem. My neighbor tells me that he tightens the bolts to the point he thinks he might strip them. Why he does that, I'm not sure, but I've suggested that he just tighten them enough so that they're snug...I don't recall ever having one of mine come loose. We'll have to wait and see what happens the next snow storm....hopefully not too soon.

 

[radioman]

Is he using the jam nuts to hold shear bolts in or using regular nuts ? Using a regular nut om a real shear bolt will need to be real tight just to prevent falling out. If he is using the supplied jam nut with the shear bolts, then put it on to a point where the bolt can slide very little up and down . It would be kinda like a 1/16 gap or hair more for bolt to slide. This would virutally eliminate all tension on shear bolt, allowing max strength before shear.

Another school of thought is that is the bolt too long? does holding jam nut run out of threads before tightening? The wrenching can add more shear forces weaking the bolt before use.

 

[Dyer retired]

Is he using the jam nuts to hold shear bolts in or using regular nuts ? Using a regular nut om a real shear bolt will need to be real tight just to prevent falling out. If he is using the supplied jam nut with the shear bolts, then put it on to a point where the bolt can slide very little up and down . It would be kinda like a 1/16 gap or hair more for bolt to slide. This would virutally eliminate all tension on shear bolt, allowing max strength before shear.

Another school of thought is that is the bolt too long? does holding jam nut run out of threads before tightening? The wrenching can add more shear forces weaking the bolt before use.

He's had both jam nuts and regular nuts with lockwashers. I've always had the bolts with the lockwashers and they work fine just snugging them up. I ordered a pile for him through Messicks when I order some new ones for my new blower and they are the nut and lockwasher combo. He'll need to tighten them a little, but certainly not to the point of thinking they are about to strip. I'll call him Ralph (because that's his name) is the type that if a little tightening is good, then overtightening is better. We'll see how this next storm does and I hope I'll be able to report good news. Dyer

 

[keyman1808]

I am assumming that he lubricated the auger and all related points. And checked the gear oil in the gear box. If the auger isnt greesed then maybe its binding as its spinning. I know it obvios but I thought I would ask

 

[DGS]

There is one other thing that I can think of and that is the shear bolt holes in the augers and the shaft. Are they perfectly round or do they have elongated holes from working against the metal. If that is the case then drilling out those holes to the next bolt size may fix your problem.
Good luck
DGS

 

[Dyer retired]

I am assumming that he lubricated the auger and all related points. And checked the gear oil in the gear box. If the auger isnt greesed then maybe its binding as its spinning. I know it obvios but I thought I would ask

He does grease it often and isn't getting any unusual noise out of it.

There is one other thing that I can think of and that is the shear bolt holes in the augers and the shaft. Are they perfectly round or do they have elongated holes from working against the metal. If that is the case then drilling out those holes to the next bolt size may fix your problem.
Good luck
DGS

The blower was new last year and doesn't show any signs of the shear bolt holes elongating. He's had the problem since it was new apparently and seemed to think it must be normal. He mentioned to me this year that he thought he was shearing a lot of them and I was surprised to hear the number. As mentioned earlier, he may have been "over" tightening the shear bolts. I think the next snow storm will provide some answers.

Thanks again for all the suggestions and I'll update you all when the next storm has given us some test material. I haven't heard of anyone else having major, unexplained, problems like this, so it appears to be something unique to how he's doing things? Dyer, retired

 

[art]

To be riding the clutch petal or the petal on the left would answer the shear bolt problem. Seen it before with bad PTO pressure in full hydraulic units and a unit like the Kubota if the left petal was being hit while under load would cause the shear pins to shear from engaging and disengaging the The PTO system.

 

[Toyboy]

I got some new 5/16 x 2 1/4 shear bolts from dealer(70060-01338) for my BX2750 blower, and the specs call for torque of 17 to 20.5 ft pounds. I set mine at 19 ft #
I also drained and refilled the worm gear box with 80-90W Mercury marine lower unit lube. The stuff that came out was nasty looking. Surprised me to see a pressure relief valve on gear box. Maybe thats how moisture got in I think I'll make that a yearly PM, easy enough to do.