Bear with me, newbie locating shear bolts on an Agro Trend 3pt blower

[cnice37]

Hi guys, I picked up a 3pt Agro Trend blower for my Kubota late summer. It was a great deal and it looks like the season is upon me to start using it.

I want to have shear bolts on hand and ready for replacement.... but first I need to locate the darn things (on the blower/ shaft that is!)

Here is the copy of my manual http://forddistributing.com/media/downloadable/files/samples/s/n/snow_blower_1000_series_manual.pdf

I see one spec'd on the PTO shaft side. There is one listed on the IPL for item 32.... but it doesn't show up in the drawing.

Where are these commonly located on the blower side?

I'm thinking McMaster Carr for some Gr.5 replacements to keep on hand.

Thanks in advance.

 

[kco]

This note on page 5 of your manual:

SHEAR BOLTS
Shear bolts are built to break under shocks on the fan or on the auger. However, under certain circumstances,
this security is not adequate. Example: A sudden high impact shock on the fan may, in some cases, break the fan
shaft without breaking the shear bolt.

If the shear bolt breaks, make sure to always replace it with a same category bolt (grade 8.8). It is necessary to
always maintain this bolt very tight, in order to keep the efficiency of the shearing mechanism

...appears to refer to a metric grade 8.8 bolt. I think that is roughly the same as an SAE grade 5.

Does the existing bolt have 8.8 stamped on it? If so it is likely the correct one for the drive shaft shear bolt and you could get a few of the same size metric bolt.

The pto shaft numbers (e.g. T50-071P) look similar to those used on my MK Martin Meteor snowblower. Mine has a T50 shaft from Italian maker, Comer.

Added later:

Looking at the drawing again...it appears item 32 you mentioned may refer to the one on the PTO as it is a 6mm(.24") x 40mm grade 8.8.

The shear bolt for the auger(item 24) is an SAE 1/4" x 1" grade 2.

My Meteor blower has the same mix, SAE on the auger and metric on the PTO.

 

[JerryK]

The main shear bolt is usually on the PTO shaft just before it hooks onto the blower... but could be somewhere else on the the shaft. This bolt trys to protect the tractor/PTO shaft, and also the blower/gearbox/etc. This is the normal shear bolt that will break due to hitting something or trying to injest something that the blower doesn't like. This bolt will also commonly break after X amount of hours just because... the because if from engaging the PTO X amount of times, sometimes at RPM... etc. If you have a chain drive for your feed auger, there is usually a shear bolt somewhere between the gear box and the first chain sprocket. This bolt hardly ever breaks [ for me, anyway ]. It is there to protect the gearbox... If the unit is new, you should remove each bolt and see if it is smooth or has a grove in it to weaken it in a spot. So you can fab up as close a replacement as possible in the future...

 

[rayclar]

on my old argo trend the shear bolt is # 24 on the parts list.

 

[cnice37]

Found them both! Thanks for the help

 

[kco]

Found them both! Thanks for the help

Just curious.....what size/grade are they, and how did you find them?

 

[JerryK]

These are the shear pins I use in my 78" JRW rear blower. I make them out of 5/16"-18 X 1 3/4" Grade 2 bolts with a long enough shank. Put a nut on the threads, cut the bolt to lenght, grind the threads to clean them up, then remove the nut to do a final clean up of the threads. Then I chuck each one into a vised up electric drill with a keyless chuck, run that drill with my left had while grinding a slight grove into the bolt with an air grinder/cutoff wheel with my right hand. I know it is a lot of work, but I would rather replace a shear bolt once a month. I have used up to Grade 5 bolts in the past [ my JRW manual said use Grade 2 ], but finally went this way to help the guy in charge sleep better at night ...

 

[cnice37]

Just curious.....what size/grade are they, and how did you find them?

I think JerryK's pics below are better than what I could have typed. Same location as mine, bottom of PTO shaft, and at the shaft/ gear connection to the chain drive. Grade 5 and not sure what the gear one is.

These are the shear pins I use in my 78" JRW rear blower. I make them out of 5/16"-18 X 1 3/4" Grade 2 bolts with a long enough shank. Put a nut on the threads, cut the bolt to lenght, grind the threads to clean them up, then remove the nut to do a final clean up of the threads. Then I chuck each one into a vised up electric drill with a keyless chuck, run that drill with my left had while grinding a slight grove into the bolt with an air grinder/cutoff wheel with my right hand. I know it is a lot of work, but I would rather replace a shear bolt once a month. I have used up to Grade 5 bolts in the past [ my JRW manual said use Grade 2 ], but finally went this way to help the guy in charge sleep better at night ...

Beautiful work, and easy enough to try myself. Appreciate the details.

 

[kco]

I was wondering if you were able to locate the grade and size from the manufacturer or the drawings.

I thought the PTO shear bolt would have been a metric gr. 8.8, 6mm x 40mm and the one for the shaft driving the auger chain is likely an SAE grade 2, 1/4". I had a heck of a time locating grade 2 1/4" bolts here but finally found one ag equipment dealer that had some. But previous to that I bought some 1/4" carriage bolts which are grade 2.

I used plastic pipe and caps to make a shear pin holder that stays on the blower:

 

[cnice37]

I was wondering if you were able to locate the grade and size from the manufacturer or the drawings.

I thought the PTO shear bolt would have been a metric gr. 8.8, 6mm x 40mm and the one for the shaft driving the auger chain is likely an SAE grade 2, 1/4". I had a heck of a time locating grade 2 1/4" bolts here but finally found one ag equipment dealer that had some. But previous to that I bought some 1/4" carriage bolts which are grade 2.

I used plastic pipe and caps to make a shear pin holder that stays on the blower:

View attachment 350036View attachment 350037

Nice, I won't get so fancy and just toss some spares under e seat. The drawings and parts list in the manual confirmed the grade and size, and I found the 6x40mm gr 8.8 no problem but the 1/4"x1" weren't as obvious. I chose a "lower strength" as listed by McMaster Carr which they claimed to be similar to Gr 2. Hope it all works out.

Thanks for the help.