Kubota stalling not breaking chipper shear pin bolt

[elf1958]

I have a 2010 Kubota L3940 and a used Wallenstein BX60 Chipper. I have killed the engine on my tractor 2 times chipping a 4" tree. The chipper jams and causes the tractor to shut off. The shear bolt did not break and after clearing the jam everything works OK. Does the L3940 have some type engine kill or is the shear bolt my only protection. I removed the shear bolt and it is a 3/8 grade 5, 3 hash marks. I do not have a manual for the BX60 chipper so I am not sure what the factory shear bolt should be.Also if anyone has a manual or procedure for adjusting the blades in the chipper I would appreciate the help.

Thanks

 

[PHILIP8N]

All shear bolts I have been around are of grade 2 material, no hash marks on head. I have never stalled my tractor, 8N or L3940, with my BearCat chipper, nor have I ever snapped the shear bolt on the chipper. Philip.

 

[Treesanddust]

After looking up the specs for both the tractor and the chipper, it looks like you are on the very low end of PTO hp for that chipper. Most likely the chipper's drivetrain is designed to handle more power than what your tractor is capable of. So the shearpin that works for a 60+ hp tractor isn't going to break before stalling your tractor unless its a very sudden stoppage.

I'd try to find a Grade 2 bolt instead of the Grade 5 bolt. But even with a Grade 2 bolt, it may still stall the tractor if its a gradual need for more hp.

 

[two4spooky]

I like Trees idea of using a lower grade bolt for the shear pin. Going real heavy with implements has draw backs. I am running a rotary cutter that is at the upper limit(or a bit past) for my tractor. I have trouble getting the slip clutch to slip at the lower RPMs I prefer to cut at. Try the lower grade bolt and let us know how it works.

 

[elf1958]

I will buy a few grade 2 bolts and try them, I sure don't want to tear anything up. It was a sudden stop and it did not even dent the shear bolt. I have the L3940 HST-3 so maybe it has some type of safety because it does not appear to have hurt my tractor but I don't want to chance it again. I know my PTO HP is in the low 30's but the chipper runs fine.

Thanks for the advise

 

[PapaPerk]

I will buy a few grade 2 bolts and try them, I sure don't want to tear anything up. It was a sudden stop and it did not even dent the shear bolt. I have the L3940 HST-3 so maybe it has some type of safety because it does not appear to have hurt my tractor but I don't want to chance it again. I know my PTO HP is in the low 30's but the chipper runs fine.

Thanks for the advise

I doubt there's a safety. You're just stalling the engine out. Another option is to replace the shear bolt with a slip clutch on the PTO shaft.... then adjust the slip clutch to slip before the tractor stalls out completely.

You may need to just chip smaller wood. What kind of wood are you pushing into it? And is it dead? Also is the chipper blades sharp? Lots of questions I know! :laughing:

 

[PapaPerk]

I just noticed your post said USED chipper.... ahhh... that maybe your problem. Check the machine to make sure it's not binding in someway and certainly make sure the chipper blades are sharp! Dull blades stop instead of slice.

 

[elf1958]

I put in a grade 2 bolt and filed a grove in it just to make sure it would break. It snapped after a couple of 2" trees. I put in another #2 bolt and chipped a few more and it seems to be fine. I took the blades off and they have a few nicks but are not real dull. I ground the nicks out and sharped then a little. The blades are reversible and the other edge has never been used so I may need to turn them around one day. The wood was a dead 4" dogwood tree so it was real hard wood. I guess I was just asking for it to do too much.

I had to guess at the blade adjustment because every blade was a different depth when I removed them.

Thanks

 

[PHILIP8N]

I try to chip only green wood. Dry wood wears out the blades more quickly, this gets burnt. Philip.

 

[mdelmarcelle]

I put in a grade 2 bolt and filed a grove in it just to make sure it would break. It snapped after a couple of 2" trees. I put in another #2 bolt and chipped a few more and it seems to be fine. I took the blades off and they have a few nicks but are not real dull. I ground the nicks out and sharped then a little. The blades are reversible and the other edge has never been used so I may need to turn them around one day. The wood was a dead 4" dogwood tree so it was real hard wood. I guess I was just asking for it to do too much.

I had to guess at the blade adjustment because every blade was a different depth when I removed them.

Thanks

I've only ever seen grade 2 bolts too. I don't have a chipper, but I have a cutter that has a shear bolt. The cutter is 6 feet and the tractor is 70hp, so it eats those bolts like candy. They're cheap though.