Conical PTO Bolt Replacement???

[Matlax]

I just picked up a stump grinder that uses a conical bolt to secure the PTO shaft to the implement side. The shaft has a clutch so I don’t think it has a protective function like a shear pin. The nut backed out and it came apart. By some miracle, nothing broke and I found the bolt. I bought a nyloc nut hoping for a better result but I don’t get a lot of thread engagement and when I check it every 30 minutes of operation, I get about a quarter turn. I’m worried I’ll forget to check that often and the next failure will be catastrophic. Can I replace it with a regular bolt that’s longer so I can put a split ring washer on there to hold the tension? Thanks for any advice!

 

[zzvyb6]

I'd drill it to be cylindrical and use a tight fit ordinary bolt. Done.

 

[Matlax]

I'd drill it to be cylindrical and use a tight fit ordinary bolt. Done.

Thanks! You’re talking about drilling the coupling so it’s a straight hole?

 

[zzvyb6]

Thanks! You’re talking about drilling the coupling so it’s a straight hole?

Yessir. I'd say the original conical bolt was intended to keep the joint tight. And, for all we know, the bolt may be conical because of its loose fitting after starting out in life as cylindrical. These couplings are usually just cast steel so not a lot of trouble. But keep the holes you wind up with as small as possible to avoid fracturing the coupling later on. Drill it as 1 assembled unit so all the holes are beholden to the holders honors..

 

[Matlax]

Yessir. I'd say the original conical bolt was intended to keep the joint tight. And, for all we know, the bolt may be conical because of its loose fitting after starting out in life as cylindrical. These couplings are usually just cast steel so not a lot of trouble. But keep the holes you wind up with as small as possible to avoid fracturing the coupling later on. Drill it as 1 assembled unit so all the holes are beholden to the holders honors..

Thanks ZZ!

 

[Matlax]

Any other thoughts on this one?

 

[D&D]

Any other thoughts on this one?

Use a nordlock washer and red loctite. Easier to find would be an internal toothed lock washer and red loctite. Other option, order a new longer conical bolt from Agrisupply, etc

 

[SPYDERLK]

Any other thoughts on this one?

Yes. Do not do away with the conical bolt fastening if it immobilizes the joint. Its meant to immobilize the joint. An immobile joint does not wear. It is permanent and unchanging. If the bolt is worn so much as to prevent this get another bolt. If that doesnt result in a stable situation then you can feel justified in thwarting the design by straight bolting it.

 

[Matlax]

Yes. Do not do away with the conical bolt fastening if it immobilizes the joint. It’s meant to immobilize the joint. An immobile joint does not wear. It is permanent and unchanging. If the bolt is worn so much as to prevent this get another bolt. If that doesnt result in a stable situation then you can feel justified in thwarting the design by straight bolting it.

Thanks Spyder. Great point. Do you know if they’re standard diameter? I’ll have to remember to bring my micrometer out there next time to get a measurement.

 

[SPYDERLK]

Thanks Spyder. Great point. Do you know if they’re standard diameter? I’ll have to remember to bring my micrometer out there next time to get a measurement.

Probably there are different sizes. The taper angle may be standard. Ive only encountered them a few times and never needed a replacement. - - Cant you get the part from the stump grinder maker?