Woods Blower keeps snapping grade 5 bolts

[KanakaRick]

Bought a woods blower a couple of years ago for my 50hp Kioti and it works like a dream, but recently it has started snapping the grade 5 shear bolts. I can hand turn the auger and then I will turn on the pto, and it instantly snaps the shear bolt. I was working great the week before, but now it is snapping shear bolts. I figured maybe I needed to have the pto drive shaft straight out from the auger u- joint, and then I turned on the pto and SNAP! I have no idea why it is snapping the grade 5's. I bought some grade 8's but I am hesitant to use them for obvious reasons. Any ideas?

 

[newbury]

Maybe try a different brand of grade 5's.

 

[LouNY]

Pop the auger drive chain off and see if you still snap shear bolts,
could be the impeller.

 

[rScotty]

The traditional cure for that is to engage the PTO clutch more slowly. But lately some tractor manufacturers have been replacing the PTO clutch with a simple on/off switch. The problem then is how to slow down the engagement.

Is there room to add an adjustable slip clutch between the PTO output and the drive to the blower? That would fix the problem.

I've never used one of those slip clutches myself, but they are common slip on units for PTO shafts & and not expensive. It's good to have one to protect the PTO internal gears anyway.
good luck,
rScotty

 

[JJT]

Are you starting the blower at full rpm? If you're easing into it at an idle, it should not be breaking shear bolts. I would not go to grade 8.

 

[KanakaRick]

nope, just at idle.

 

[KanakaRick]

Pop the auger drive chain off and see if you still snap shear bolts,
could be the impeller.

I can turn the impeller with my hand, so it doesn't have any rotating issues.

 

[KanakaRick]

The traditional cure for that is to engage the PTO clutch more slowly. But lately some tractor manufacturers have been replacing the PTO clutch with a simple on/off switch. The problem then is how to slow down the engagement.

Is there room to add an adjustable slip clutch between the PTO output and the drive to the blower? That would fix the problem.

I've never used one of those slip clutches myself, but they are common slip on units for PTO shafts & and not expensive. It's good to have one to protect the PTO internal gears anyway.
good luck,
rScotty

it's a 2002 Kioti, and i have no idea about slip clutches.

 

[KanakaRick]

Maybe try a different brand of grade 5's.

That's what I was thinking. The tractor is at idle, and as soon as I turn the button on that turns on the pto, the bolt snaps. A couple of days ago, it worked fine, but now I have no idea. After the bolt has snapped, I can turn the auger with my hand, so there isn't anything in the auger that would prevent it from turning.

 

[RoyJackson]

Easiest thing is to try another brand pf Grade 5 bolts.
It's an unfortunate fact that there are counterfeit bolts...lower grade then what's advertised or marked on the head. Very serious problem with Grade 8's, but that isn't limited to the harder grades.

 

[jigs_n_fixtures]

Can you spin the input easily by hand? If you can, do you feel any unevenness when you do?

I’m thinking there may be a bad bearing in the 90-degree gearbox, which is causing
it to bind up when input is applied via the PTO, but not when you turn the impeller, sending the load in from the other side.

 

[oosik]

Don't go to the grade 8 bolts. As suggested, try an alternate brand of grade 5.

Also thinking the "bad bearing/worn bushing" , as suggested by jigs could be the cause.

Obviously - something is binding up when you apply power. Is everything well greased up?

 

[RandyT]

If this thing has sheared several bolts over time the holes that the bolt goes through could be getting flogged out which can lead to the problem that you are having. But could also be a chipped gear in the drive box that is jamming when pressure is applied but may not show up when turning by hand.

 

[LD1]

Does the tractor ALSO have a foot clutch.

I know it isn't "needed" to engage PTO on most modern tractors. But if the clutch pedal does indeed disengage the PTO (it does on my Kubota MX)....by pushing the clutch, then engaging the PTO, it allows you to slowly engage the implement

 

[5030]

Chinese Grade 5 maybe?

 

[RoyJackson]

Does the tractor ALSO have a foot clutch.

I know it isn't "needed" to engage PTO on most modern tractors. But if the clutch pedal does indeed disengage the PTO (it does on my Kubota MX)....by pushing the clutch, then engaging the PTO, it allows you to slowly engage the implement

I doubt if too many TBNers have a gear tractor with a live PTO anymore. I had a couple in the old days (Deere 670 and 790), and LD1's post exactly describes the process. I'll add one thing...if the tractor has a foot throttle, be prepared to "blip" the RPM when engaging the PTO.

 

[LD1]

I doubt if too many TBNers have a gear tractor with a live PTO anymore. I had a couple in the old days (Deere 670 and 790), and LD1's post exactly describes the process. I'll add one thing...if the tractor has a foot throttle, be prepared to "blip" the RPM when engaging the PTO.

Yup, most of these small tractors anymore are HST. But up until 8-10 years ago....most still had a clutch.

Only recently have they gone away from that so they could put the split brakes on the left side.

Some like it that way. Personally I still prefer the clutch. Cause it still disengages the PTO. Doing alot of brush mowing....that's my first oh $hit instinct is to stop on clutch when something sounds amiss. And it also allows feathering the engagement.

I think the OP said his tractor was a 2002 model. I would think it still has a clutch.

The ONLY implements I use that I DONT feather the clutch to ease the engagement on are things with little inertial load. Like a seed spreader, or PHD.

 

[leonz]

A slip clutch ends up being mounted on the gear box side of the trailing implement but if there is little room it could be mounted on the stub shaft of the PTO.

 

[ruffdog]

Are the shear bolts shouldered through the shear area or are there threads at the shear point? If it is threaded, you may want to get longer bolts that have the longer shoulder, then cut off excess threads. Also, most use a locking nut and are just snugged...not over tightened.

 

[ArlyA]

The OP was doing fine with the grade 5 bolts, untill he wasn't. Something changed.