Woods Blower keeps snapping grade 5 bolts

[Jims1025R]

Something has changed, snapping bolts at an idle unloaded.
Even chineee grade 2 should be fine unloaded.
Something is wrong some place even though it turns fine by hand.
It could be in the impeller, the gear box, even the chain it's self or the auger.
Until the components are separated it will be looking for the proverbial needle in the haystack,
just not so many pieces.
It could be an issue which shows it's ugly hear at a faster speed then turning by hand achieves.

This.

If you can tighten the nut on the shear bolt decently, without breaking the bolt - it's not a failing of the bolt that it's shearing. If the bolt is too junky (which could be found, if you really tried) tightening the nut would break the bolt.

Do not use stronger bolts:

Understand the system, examine for defects, and keep searching until you find whatever is wrong, and fix it correctly. Exactly the same reasoning as don't replace a blown fuse with one of a greater rating just because the correct one keeps blowing, fix the problem and use the correct fuse!

 

[KanakaRick]

Actually, I haven't greased the u-joints.... maybe I'll try that.

So the foot clutch also engages the pto? Really? Didn't know that.... I may try that. It's worth a try.... it is dumping outside and I need that blower.

Pressing the clutch doesn't affect the speed of the PTO... that's probably why I didn't try that.

 

[Deere Dude]

Try actual shear bolts from a tractor dealer. Just an idea.

 

[RoyJackson]

Pressing the clutch doesn't affect the speed of the PTO... that's probably why I didn't try that.

No, but engaging any load on the clutch does lower engine RPM

 

[KanakaRick]

So, there was a brief break in the series of storms, so I dug out the snowblower and put it back on the tractor. I greased every fitting copiously and attached the driveshaft to the tractor and turned the pto on...... and it didn't snap. So I am guessing the ungreased joints perhaps had something to do with it. We will see, but for now it looks like it may work. I'll find out tomorrow morning. Thanks for all the ideas.

 

[RoyJackson]

So, there was a brief break in the series of storms, so I dug out the snowblower and put it back on the tractor. I greased every fitting copiously and attached the driveshaft to the tractor and turned the pto on...... and it didn't snap. So I am guessing the ungreased joints perhaps had something to do with it. We will see, but for now it looks like it may work. I'll find out tomorrow morning. Thanks for all the ideas.

Best of luck and keep us posted

 

[KanakaRick]

I am now thinking that it was a cheap batch of grade 5's. When I snapped another today by sucking a tree branch in the blower, I went through several more snapping, and then I used a little longer and older purchase date bolt and it worked fine. I think it was just cheap shear bolts. Thanks for everyone's replys.

 

[michaelgs]

Just wondering, is the pto shutting off then when engaged the engine is then at over 2000 rpm? This kind of jolt was causing my snowblower to shear bolts. Mike

 

[Jac65]

Sounds like a bad batch of bolts. You can also throttle down the idle as low as it will go, press the foot clutch and engage the PTO then ease off the clutch and see if the bolt will hold at min rotation speed. you can throttle up from there and see if they hold.

 

[KanakaRick]

So, I am guessing that some loose fan bolts were the cause of the snapping of the shear pins. Boy what a tricky way to tighten the fan bolts, but I got it tightened up. I haven't tried it yet, as I needed to put my rear blade on to cut some ice on the driveway, and I (apparently) forgot to disconnect the wiring to the chute rotation and the deflection motors, so when I drove away, I ripped all the wiring out. I take 2 steps ahead and 3 steps backwards. A big DUH moment. When I get everything wired up I again I will reconnect to see if I am snapping shears again.